Disclaimer: If you are not comfortable with the command line, do not try this.

If you have installed an app from the Ovi Store web portal, you would have noticed that the process is not fast. Clicking the Download link opens the Application-Manager which takes anywhere from 30-40 seconds to prepare the system before actually starting the download. For those who don’t like to wait, the apt-get command is a great alternative to speed up things and also allow installing multiple apps (at least the ones that are free) in one go.

Prerequisites

There are two things required before starting the download. Setting up the Ovi Repo and creating an Archive folder. You need to do this only once.

Ovi Repo

If you have never used the Ovi Store, you would need to have the repo installed first. Downloading an app from the store automatically adds the repo the first time but you need an Ovi account. So if you want the apps but don’t like signing in, you can add the repo manually:
Name: Ovi
Web: https://downloads.maemo.nokia.com/fremantle/ovi/
Dist: ./

Archive Folder:

In order to save space on the root partition, create a download directory for the downloaded packages. Instructions here

Installation

For installation, all you need is the application’s package name. The apt-cache command can be used to find it. The following command will search and list all packages with the word ‘offscr’ in it:

# apt-cache search offscr

This will display the 31 nifty apps by Offscr currently available. This also searches descriptions.

Next, install the desired package using apt-get (as root of course):

# apt-get -o dir::cache=/home/user/MyDocs/apt-archive-cache install  offscr-discs  offscr-backgammon  offscr-watch

This will start the installation process for all 3 apps which will take about the same time it takes for one install from the website. Enjoy!

Latest Mobile Phones 2010

Hi folks a major firmware update for Nokia N900 is out. The Update is called PR  1.1 Release1.2009.42.11 to PR1.1 release 2.2009.51. Maemo 5 PR1.1 is being released on January 14, 2010. Starting in Finland at 7am local time and following a staggering process country by country through the different time zones.

This update can be installed over the air by users with the PR1.0.1 already installed. Images for flashing will be available later today as well.

The Maemo 5 SDK and tools are being updated as well in order to match the OS content. The update will be available later today.

Tons of Changelogs after the break!

New features

• Hutchison SIM cards are supported.
• MS Exchange 2003 support.

Maemo Update

• Bootloader (Nolo) can be updated over Maemo Update.
• Cellular software can be updated over Maemo Update.
• Icon cache removed to allow more memory space for Maemo Update.
• Application Manager: Available space check moved to apt-worker for more accurate results.

Reliability

• Improvements in SGX performance and reliability.

Use-time and power consumption

• API for status area applets to detect if they are invisible/absent.
• Fixes to Pulseaudio timer increasing power saving when starting/closing apps.
• Browser: Removed unnecessary serial logging.
• Reduction of wake-ups in Desktop, Connectivity, Conversations, RSS Feed Reader,
• Backup handles correctly directories containing pairs of symlinks.
• Less CPU load caused during video recording.
• Support disabling Virtual Keyboard in input field.
• Performance improvements in Browser.
• Lock: “swipe to unlock” will not stay on.
• CPU idle latencies and thresholds updated.
• Fixing eMMC data lines while sleeping.
• CellMO power consumption reduced.

Usability

• Volume button operation in call flipped based on audio routing (no more on screen orientation).
• Browser: Downloading & rendering of page content runs promptly.
• Helping to avoid capacity limits of rootfs when installing apps (make Docpurge aware of /opt).
• Stability and usability fixes to the Profiles applet. Selection, usage and restoring of ringtones.
• Fast call from home shortcuts.
• Fast SMS rejection of incoming call.
• Avoid false alarms in pocket.
• Silence ringing by flipping face down.
• Fix to Camera photo orientation problem: correct orientation is now written to EXIF.

Performance

• X: performance of GLES apps improved.
• Lower RAM consumption while capturing video.
• Phone-UI & Msg-UI always ready to appear.
• Application Manager UI speed improvements.
• Email faster with large mailboxes.
• Large file copy (SD->MMC) doesn’t degrade system performance.

OVI Maps

• Route calculation and search performance improved.

Connectivity

• BT Secure Simple Pairing fixed for Windows Vista.
• BT transfer progress indicated.
• Improving WLAN connection stability.
• Improved WLAN negotiation when going out of reach of access point.

Phonecalls

• Add voicemail shortcut support.
• Showing call forwarding correctly when busy forwarding is not set.
• Call log improved.

Audio & Video

• Audio volume control works with +/- keys in full-screen playback of flash.
• Handling corrupted ring tone files better.
• HW volume keys always have same orientation.
• Media Player UI now provides feedback when tapping control buttons in video playback.
• MIC input not clipped when loud voice in VoIP call.
• Pulseaudio: Ringtone is heard from the loudspeaker if BT connected.
• Ringtone played both to headset (BT or wired) and to internal HF speakers.
• AV sync fix for recorded videos.

Camera

• ISO EXIF value for images saved when automatic sensitivity in use.
• Vignetting test of 2nd camera fixed, VGA sensor stability.

Battery and Charging

• Improved charging in case of low charging power (PC USB charging).

USB

• Fixing the USB detection and card mounting issue related to quickly attaching/detaching the cable.
• Able to format corrupted eMMC properly.
• Hang fixed in case of WLAN disconnection while copying files.

Synchronization

• Activesync supports now MS Exchange 2003.
• Activesync – fixes the forwarding of attachments showing incorrect sizes (Exchange server 2003).
• Content copier of PC Suite enabled. Whole content backup (including Notes) can now be restored from PCSuite.

3rd party applications

• Policy-settings: Fixes rotation transition in for 3rd party applications.
• Policy-settings: By default, 3rd party apps should have the same limits as our applications.

Calendar

• Public API for color picker. Home widget is now translucent.
• Set/get alarms API.
• Syncing of task alarms supported.

Image Viewer

• Thumbnailing faster.

Application Manager

• Rename Maemo Extras to maemo.org and enable by default.
• Grid view applied for the categories in download view. Added API for filtering packages.

Development Platform

• SDK content and tools updated.
• SDK GUI installer updated.
• New sharing-dialog-dev package added to enable Bluetooth and email sending.
• New wappushd-dev package documenting MMS interfaces available.

Community reports fixed

Browser

* “”About Flash Player”" contextual menu item treated as unrequested pop-up
* Focus not set to location bar after Ctrl-L shortcut is used
* Spacebar scrolls more than 1 page
* microb doesn’t trigger onchange
* Page is not rerendered when JavaScript actions increase page length
* Complete Browsing History on the N900 sometimes displays “”None”"
* The menu item “”copy”" in the browser menu does not work
* OK button remains disabled in dialog for Integer settings in about:config
* Browser window checkerboards and repaints when navigated to from multi-task view
* Sometimes the browser window goes black for over a second after clicking the fullscreen/restore button

Calendar

* Start and end times are changing when daylight saving time ends (begins)
* Incorrect entries in the Birthday Smart Calendar
* Changing to next week is very slow
* Smart birthday-widget doesn’t show up any birthdays or shows one on random

Chat & Call & SMS

* Phone app crashed as call ending
* Dialer does not accept SS (3GPP TS 22.030) dial strings
* Unclear how to open a contact (sender/receiver) of a conversation
* High latency between UI and SIP events being sent
* clicking on notification window fails for 2 or more messages when in Dashboard
* Skype does not allow entering DTMF tones
* skype: Call does not support DTMF tones
* Can’t send sms/chat to known contact from the Call list
* libnice violates Debian packaging policy for description of package “”libnice0″”
* Volume buttons should be swapped when using the phone in portrait mode.
* Call Log only displays contact name that called, not phone number
* Show wrong Contact for a SMS after a couple of days
* scrollbar instead of kinetic scrolling
* Chat window for jabber / xmpp is not always updated with new incoming messages

Connectivity

* Bluetooth DBUS UI dialogs – wrong args in the example code
* Button style in Bluetooth file receive applet is wrong
* Inconsistent keyboard behaviour when configuring a static ip address
* Drops WLAN connection to Linksys WRT610N after 10-15 minutes
* after failed pairing to bluetooth car kit bluetooth can’t be turned on
* Wrong settings for Orange (France) gprs
* udhcpc overriding default routes

Contacts

* address book cannot import vcards from benq/siemens phones properly
* Contacts re-appear in list after disableing and re-enableing accounts
* No hint that it is impossible to paste an strings containing non-numeric characters into a phone number field
* Skype Support>Report problem leads to an error page

Core

* N900 sometimes ignores USB data cable

Desktop platform

* Publish sources of alarm framework
* Failed to build libosso-2.19 from Fremantle repo (ggc 4.3.2)
* wdgt_va_full_12h_time, wdgt_va_12h_hours should be replaced by wdgt_va_full_12h_time_am/wdgt_va_full_12h_time_pm and wdgt_va_12h_hours_am/wdgt_va_12h_hours_pm
* Easy to enter ~ ^ ‘ ` “” symbols with 3rd row of special character view
* “”More…”" applications launcher does’t allow scrolling
* Can’t easily align desktop widgets (snap to position) on home screens
* Allow keyboard input to jump to an entry in a list (“”type ahead”")
* No rubber-banding effect in the Main “”More…”" menu (task launcher)
* WiFi password shows up in auto-completion
* When applying a different theme, not all colors change in application manager
* libsdl: Task switcher area can be a dead area
* FN-lock and Ctrl+Backspace breaks input for used application
* Application Manager moves to background after start when quickly clicking
* Typing in newly opened window brings up contact search
* Race condition with hardware shift key
* Home view blurs on triple-tapping the launcher grid icon
* Hanging application menu requires system reboot
* Rotation in 42-11 is not as smooth as in 41-10 for some third party apps
* “”More…”" view is not sorted at all
* Add a (short shown) scroll bar in the status area window to indicate that there are more elements inside as actually shown
* Updating software removes desktop shortcuts

Desktop Widgets

* AP News Widget causes Excessive CPU wakeups
* Contact widgets move to active desktop after merge
* Media Player widget suddenly starts music after Phone call ends

Development Platform

* Link to C code not working (not a link in fact) on Fremantle camera api dev page
* Package downloads should be retried when the http connection time-outs
* Link for osso_wlan documentation broken
* Video indexing failed in SDK (Tracker issue?)
* xkbdata: Inconsistency between installed packages in SDK and FW
* example source code not available in “Writing a new maemo application”
* e2fsprogs derivative packages not available?
* HildonTouchSelector example has wrong parameters in callback function
* URL for sharing plugin template missing

Email

* Does not always mark e-mails as read (dovecot/cyrus/google IMAP server)
* Modest reports email username / password incorrect when it is correct
* Performance is unusable on IMAP accounts with a large number of messages in one or more folders (e.g. INBOX)
* When an IMAP account is selected, only refresh that account’s folders
* Locales not working correctly
* Deleting email should be more evident…
* Fix modest compilation warning
* Remove HildonDialog deprecated symbol
* Import conic support only if It’s available
* Remove Hildon 0.x conditional code
* Remove Hildon 1.x conditional code in Hildon2 version of modest
* Modest doesn’t take care of preferences for automatic update
* New email notification leads to blank email instead of email itself
* Double-tapping “”Inbox”" sometimes opens ‘empty’ Inbox
* nokia messaging doesn’t synchronize selected imap folders
* Long delays when opening emails – viewer window shows “”Updating”"

Images and Camera

* When ISO sensitivity is set to automatic, ISO EXIF value in resulting image is 0
* Vertical photos from other devices should fill more space when shown in portrait.
* User-facing camera produces a left side dark vertical band
* Audio does not sync with video (and is ultimately unsyncable)
* Improve zooming

Location

* Bluetooth GPS reconnect dialog refuses to go away after clicking “”No”"

Map

* USA localization displays distance in kilometers
* Can’t delete route waypoints in Map application
* Route Settings screen is not finger friendly

Media player

* Information on artist / track not updated in media player with internet radio
* Plays next radio station when current station cuts out / has playback issues
* flashing pixels around the lock button if media player is playing a video.
* Media player track search only matches the beginning of title/artist
* Viewing songs by “”Artists”" automatically scrolls to the end of the list

Multimedia

* N900 needs to be rebooted if media player fails to play video (h264dec)
* Volume in media player jumps when receiving emails, IM´s or sms´s
* Can’t change FM TX radio station name
* Xvid encoded videos unwatchable

Settings and Maintenance

* Streamlining user access to the Extras repository
* Should remember position in packages list after installing package
* Other Category appears twice
* Installing many packages at a time via App Manager exhausts rootfs space
* Artifacts (visual noise) when tapping screen in Screen Calibration
* docpurge is not aware of /opt
* Inconsistent layout on similar Sharing/VOIP applets
* Background image settings not restored

Sharing

* Evernote uses to much space in root partition, should use /opt

Statusbar Widgets

* Volume slider doesn’t notice when you plug in headphones
* Currently active connection should be first in Connections list

Synchronization

* First Synchronization between N900 and Exchange 2003 Server always fails
* MfE spams screen with error messages when it cannot connect to the server
* MfE wont keep Exchange account updated
* Changing password on Exchange 2007 makes MfE go crazy
* Company Directory not present
* MfE is missing some CA cert symlinks on some devices (NuevaSync)
* Initial sync fails with exchange 2007

System Analysis

* getbootstate bricks the device after 17 reboots if there are no normal boots in between them

System software

* Shaking device switches between landscape and portrait modes
* Charger not recognized when plugged in when in Touch & Key lock
* Low power/battery beep does not sound if you’re on a call
* Pin / lock code entry dialog reveals digits on backspace
* Alarm clock does not wake me up when battery has died.

Telephony

* 3 Mobile SIM card rejected
* Call forwarding settings not being saved
* No pause before sending DTMF tones

Translations

* Change ‘TV uit’ (TV out) to ‘TV-uitgang’
* “Ładowanie” used without distinction between “”charging”" and “”loading”"
* addr_va_lastname has a comma that it shouldn’t have
* IP address field in WiFi advanced settings partially hidden (“”Recuperar automáticamente dirección IP”" string too long)
* Some sentences in the User Guide don’t make sense
* Wrong profile names in the User Guide
* Delete dialog text missing a space
* Polish string too long in UPnP browsing menu bar
* Wrong PO Box translation for CZ language

Utilities

* Re-enable reset and/or reset-and-clear in osso-xterm
* “”Already at minimum / maximum font size.”" not translated
* File manager fails to show folder sizes beyond 999,9 MB
* Clock alarm status icon is sometimes shown as dash (-)”

We all know N900 doesn’t yet feature a MMS sending capability. mkMMS is an application developed by Mohammed Sameer

The application is not yet finished. It’s in alpha stage but it’s working good. It lacks GUI and very limited in features.This application allows you to create a MMS and send your photo to another phone number via Nokia N900. With the current version you can attach only ONE, which can be jpg, png, gif or text file (txt). And at this point it’s still under development so we can get a full featured version very soon!. You can use it like this

./mkmms /home/temp/photo.jpg m-send-req.mms subject

You can get a Copy of mkMMS here : mkMMS

This is a Python tutorial that tries to touch on most areas of the Python language, but attempts to be very simple so that people who have never done any sort of programming can grasp it. Special attention will be given to its use as a Maemo OS development platform. The content of this tutorial is provided under the Creative Commons Attribution-Share Alike 3.0 license:

http://creativecommons.org/licenses/by-sa/3.0/

http://creativecommons.org/licenses/by-sa/3.0/legalcode

The versions of Python and other libraries targeted by the tutorial will be initially the ones available on Maemo 5 at the time of the N900 release. That means Python 2.5.4. As Maemo starts moving to more recent versions of Python we will attempt to keep this tutorial in sync.

If you have any other comments or suggestions please let me know. We have a Google Wave available for those that would like to contribute to the content.

Due to its length, we have divided the tutorial in two parts (maybe three by the time we are done). There are a few sections still missing at the end of the tutorial. We hope to add them in the near future. But, again, if someone would like to help, let us know.

Table of Contents

Part One

• What is Python?
• Why Python?
• Installing Python
• How Python works
• The building blocks of a Python program
  • Variables
  • Expressions
  • Numbers
  • Strings
  • Lists
  • Tuples
  • Dictionaries
• How to program in Python
  • “for” loops
  • “truth” tests
  • “while” Loops
  • “if” statements

Part Two

• Functions
  • Defining a function
  • Namespaces and Scope
• Modules
• Working with files
• Classes and Objects
• Errors and Error Handling
• Other common built-in functions
• Time

Part Three

• GUI – Qt development
• GUI – GTK development
• Maemo/N900 specific modules
• Bibliography (attributions)

What is Python?

Python is a computer programming language created initially by Guido Van Rossum, who released it to the world as an “Open Source” “Free”program. It has since then been progressively improved by the contributions of hundreds of computer programmers around the world. The Python package can be downloaded gratis from the internet for every major computing platform in existence. It can be used and even modified for just about any purpose.

Why Python?

There are many computer programming languages in existence. They all have different advantages and disadvantages. The brain of a computer is its processor. No processor understands English. The processor needs to receive input in a format that it understands. Most processors are made to understand commands formatted as a series of zeros “0” and ones “1”. This format is called binary. It is possible to write programs by hand using this format of zeros and ones, but it is very difficult, time consuming, and error prone. That is why computer programming languages have been invented.

Programming languages are frequently categorized as “low level” or “high level”. Low level languages were the first ones to appear. They simplified the process of writing instructions to the computer by allowing the use of normal words to be used in writing the program. A translator program, a “compiler”, translates the program’s instructions into a binary file that can then be understood by the processor. However, low level programming languages are still quite difficult to master. They force the programmer to understand the way the computer works internally. The programmer has to give instructions for every step that the computer must take to handle a certain task, which can easily lead to errors and serious problems. On the other hand, low level programs tend to be quite fast and efficient (if done correctly).

High level languages are designed to make it easier to program on. The instructions look more like normal language. And, a lot of the details are handled by the compiler. This makes for much shorter development time, but can also mean that the program is not as fast and efficient as a program would be if done in a lower level programming language.

Python is a very high level programming language. Many consider it the easiest programming language to learn and to program on. Many common tasks that would normally have to be programmed by the programmer are already built in to the language. Python is very useful as an easy and quick way to program anything from small little scripts to large scale client/server systems. This is especially true with today’s ultra fast computers that make up for the speed disadvantage inherent to high level programming languages. Programmers tend to like Python because of its clean and logical syntax, which shortens development cycles tremendously. It also forces programmers to use code indentation correctly. At first, some programmers see this as a challenge and unnecessary restriction. However, not long after beginning to use it, most programmers realize that it is easy to adjust to it and that it results in very clean code which is easily maintained (even if the code was written by someone else).

Installing Python

To install Python on the N900, just install an aplication that uses Python. For example, pyGTKeditor and/or (any one knows of a good PyQt app for Maemo?).

If you are using Linux, Python should already be installed. On Windows, just go to www.python.org/download/ and get yourself a download of Python 2.6.4, not the latest 3.x, since Python 3.x code is not compatible with the one on the N900. (It is really not too different, but different enough to break things.)

How Python works

Python programs run with the aid of an “interpreter”. The interpreter is a program that converts the code into the binary instructions needed by the processor, at run time. There is an interpreter for each different platform where Python runs. This allows Python code written in a Windows machine, to run unchanged, in a Linux machine, a Macintosh machine, or even a smart phone. Of course, Python also has a lot of “platform specific” features that are optimized for the platform for which they are written. (Avoid these if you don’t want to tie your program down to a specific platform.) The interpreter must, either be installed on the computer that needs to run the Python program, or the Python program must be packaged in conjunction with the interpreter so that it can be run by computers without Python.

The interpreter can be run directly in what is called the “Interactive Command Line”. Python commands can be typed directly into this session and they are processed immediately showing the results of the command. This unique feature allows for quick and easy testing of ideas and code.

Most Python programs, however, are written with some type of text editor, saved as plain text files with a .py extension, and run as an independent process. Since there is no need to “compile” a Python program before running it, a programmer can test its changes to the code immediately after saving them.

The building blocks of a Python program

First of all, what is a “program”? Well, “a program is a sequence of instructions that specifies how to perform a computation.” *i

Enter Python’s interactive mode ( On the N900, open the Terminal application and enter the following command: python), and let’s do our first program as it is traditionally done:

>>> print "Hello World"

Hello World

Here, the word “print” is a built in command or “statement” that sends the given argument to the screen. The second part of the program, what follows the print statement, is the argument itself, in this case, the string “Hello World”. The quote marks tell Python to treat the words inside of them as a string, rather than as a command or a variable. (A “string” is a sequence of characters, like a word, a sentence, etc. They are further explained latter in this section.)

Note:
Typically, in Python manuals and tutorials, when showing python code entered in an interactive session the >>> represents the Python Command Line prompt. When a compound statement is being defined (one that takes more than one line), Python switches to ‘…’ as a prompt.

Note:
Text typed after a # is referred to as a comment, and is ignored by the Python interpreter.

Variables

What is a variable? A variable is a name (a word) that refers to a certain value. We can use almost any word and assign a value to it. For example:

>>> hi = "Hello World"

The word hi is now the name of a variable who’s value is the string "Hello World". Let’s use the print statement to send the value of hi to the screen:

>>> print hi

Hello World

In Python, variables are very flexible. You don’t have to declare them first, like in other languages. You can assign any value to them, even if they already have a value of a different type. For example, let’s change the value of hi to 3.0:

>>> hi = 3.0

>>> print hi

3.0

We can also assign a variable as the value of a variable. For example:

>>> num = hi

>>> print num

3.0

Another neat feature of Python’s interactive shell is that you don’t even have to use the print statement to see the values of variables and other objects. You can simply type their name and Python will display it.

>>> num

3.0

Expressions

At the interactive command prompt one can type expressions and see their result interactively. “An expression is a combination of variables, operators and values that represents a single result value”i. For example:

>>> num + 2

5.0

>>> ((5 – 1) + num) * 2

14.0

We can assign the value of an expression to a variable. Such as:

>>> numb = ((5 – 1) + num) * 2

>>> numb

14.0

Numbers

Notice on this last example that the number returned by Python is a number with a decimal point. In computer terminology this is called a floating point number. Since the expression included a floating point number (3.0), the expression’s value was automatically converted into a floating point number. The reason for the distinction in number types is beyond the scope of this tutorial. In most computer programming languages, one has to be careful to use the right type of number for each application. In Python, it is good to know that there are different types of numbers, but Python will usually deal with the details quite well. The only caveat to currently watch out for is division. Notice this:

>>> 7 / 2

3

Since both numbers in the division are integers (a type of number without decimal places) Python performs an integer division. This may not be what someone new to programming expects. Currently, to work around this one can do things like this:

>>> 7.0 / 2     # or float(7) / 2

3.5

In more recent versions of Python (version 3.x), Python’s designers have decided to change the way this works so that it does what new users would expect. With the current version of Python in Maemo 5 one can already import this behavior from the “__future__” module. We will see more about ‘importing’ latter.

Some common operators associated with numbers are:

There are also many math functions in Python for doing just about any operation needed. Here is a small sample (see the documentation for more). To access them you need to first import them from the math module, like this for example:

from math import acos

A handy tip is that in the Interactive Command Prompt you can recall the last printed expression with the underscore character “_”. So for example, you can use Python as a handy calculator this way:

>>> 2 + 2

4

>>> _ + 6

10

There is also a special Python extension called Numerical Python (NumPy) which allows it to become a tool for higher math functions such as linear algebra and matrices. But, enough of numbers for now.

Strings

We already saw an example of a string in the “Hello World” example. “A string is an ordered collection of characters, used to store and represent text-based information”. Python strings can be enclosed in double, single, or even triple (for multi-line strings) quotes. For example:

>>> 'Hello World'

'Hello World'

>>> "Hello 'Hello World'"

"Hello 'Hello World'"

>>> '''This is a longer string that spans

… several lines, doesn’t say anything

… meaningful, and ends here'''

The fact that strings are “ordered” means that we can access their components by position. Each character in a string has an index position before it. For example the string “Python” has the following indexes:

String Indexes

Notice that the first character “P” is located at index 0, as in programming languages like C, not 1 as in languages like Basic. However, unlike C, with Python you can also use negative indexes, which start counting from the end of the string.

To get the characters located at certain indexes we can use their index number inside brackets. Let’s look at some examples.

To get the character located at the beginning of the string we can use:

>>> "Python"[0]

'P'

Or if we are using a variable:

>>> hw = "Hello World"

>>> hw[0]

'H'

>>> hw[1]

'e'

>>> hw[-1]

'd'

We can also get “slices” of a string by specifying the first and last index of the slice separated by a colon.

>>> hw[1:7]

'ello W'

>>> hw[4:-2]

‘o Wor’

The left or right bounds of the string can be specified in a slice by leaving the index blank. For example:

>>> hw[:5]

'Hello'

>>> hw[6:]

'World'

>>> hw[:]

'Hello World'

Strings are very smart “objects”. They know how to behave correctly in many situations such as:

When adding a string to a string

>>> hw + " Today"

'Hello World Today'

>>> hw[:5] + " You"

'Hello You'

Multiplication

>>> hw[:6] * 5

'Hello Hello Hello Hello Hello '

Notice that in all the operations we have done so far with strings, the operation returns a result but the original string remains unchanged. That is how strings work. A string is what is called an “immutable sequence”. What this means is that to change a string we actually have to create a new string. For example:

Trying to change the value of a string character in place

>>> hw[0] = "M"

Raises an error!

However, since variables are so flexible we can simply assign a new value to it:

>>> hw= "M" + hw[1:]

>>> hw

'Mello World'

This works because the hw[1:] expression is calculated first, then “M” is added to it, and finally the result is assigned as the value of the variable hw.

Another way to join strings with variables is by means of string formatting. For example, what if you had a program that greets the user by name according to the time of day. For example, it could say something like: “Hi Joe. How are you this morning?”. In this case the program could gather the name of the user somehow and place it in a variable called “name”. It could also fetch the time of the day by looking at the computers clock, determine if it is morning, afternoon, or evening, and place the result in a variable called “time_of_day”. You could then have the following line in your program to merge them into a string:

>>> Greeting = "Hi %s. How are you this %s" % (name, time_of_day)

Python replaces the occurrences %s with the respective variable in the tuple after the % character. (A “tuple” is a sequence of items inside a parentheses. Tuples are further explained latter in this book.) Here is another example:

>>> dessert = "Pecan Pie"

>>> max_per_person = 1

>>> answer = "The dessert of the day is %s. You can only take %i per person" % (dessert, max_per_person)

>>> answer

"The dessert of the day is Pecan Pie. You can only take 1 per person"

In this example we added a string variable and an integer variable into the answer string. Strings and integers have different formatting codes (%s, %i). See Python’s documentation for other formatting codes.

Strings also have built-in methods such as the following:

>>> "hello".capitalize()

'Hello'

>>> "HELLO".lower()

'hello'

>>> 'hello'.upper()

'HELLO'

>>> 'Hello World'.replace(" ", "-")     #Replace occurrences of first parameter with second

'Hello-World'

>>> ' Hello World '.lstrip()     #To strip the whitespace at the left of string

'Hello World '

>>> ' Hello World '.rstrip()     #To strip the whitespace at the right of string

' Hello World'

>>> ' Hello World '.strip()     #To strip the whitespace at the left and right

'Hello World'

>>> "This is a longer string".split()

['This', 'is', 'a', 'longer', 'string']

On the last example we see how the split method returns a list of strings. It separates the original string by some given delimiter. When none is given, the default, whitespace, is used. But, what is a list?

Lists

Like strings, lists are ordered sequences. So, they share many of the same functionality. However, lists are mutable sequences, that is we can change them in place. Also, unlike strings, lists can contain any type of object: numbers, strings, even other lists. Much of the simplicity, power, and popularity of Python comes from this built in object type.

To define a list, we simply have to enclose it in square brackets using commas as item delimiters:

>>> L = [1, 2,'three', 4]

The L variable is now a list object. We can use indexes and slices to access its members:

>>> L[0]

'1'

>>> L[2:]

['three', 4]

And, as mentioned before, we can change them in place:

>>> L[2] = 3

>>> L

[1, 2, 3, 4]

>>> L[0] = ['one', 'two', 'three']

>>> L

[['one', 'two', 'three'], 2, 3, 4]

We can also concatenate lists (add them together):

>>> L + [8, 9]

[['one', 'two', 'three'], 2, 3, 4, 8, 9]

And repeat or multiply:

>>> [1, 2, 3] * 3

[1, 2, 3, 1, 2, 3, 1, 2, 3]

We can delete items from lists using the del function:

>>> L = [['one', 'two', 'three'], 2, 3, 4]

del L[1]

L

[['one', 'two', 'three'], 3, 4]

Or even:

del L[0][1]     #Deletes item at index 1 of L[0]

L

[['one', 'three'], 3, 4]

Lists can be sorted and reverse sorted:

>>> L = ['c', 'b', 'a', 1]

>>> L.sort()

>>> L

[1, 'a', 'b', 'c']

>>> L.reverse()

>>> L

['c', 'b', 'a', 1]

Notice that the sort and reverse methods do not return a new sorted list as a result. They simply change the list in place and return a special value called None. To see the results of the sort we have to print the list.

Another little peculiarity to watch out for when using lists is the following:

>>> L1 = [1, 2, 3]

>>> L2 = L1

>>> L2

[1, 2, 3]

>>> L2[0] = 8

>>> L2

[8, 2, 3]

>>> L1

[8, 2, 3]

Notice that changing an item in L2 also changed it in L1. The reason for this is that when we assign L1 as the value of L2 what Python actually does is assign a pointer to L1 as the value of L2. In other words, they are linked. If this is not the desired result, you can avoid it by doing the following:

L2 = L1[:]

Because slices return new lists, assigning a slice of all the items of L1 as the value of L2 results in L2 being a new, independent list, a clone of L1.

So as you can see lists are very easy and friendly to use. In Python lists have a very close relative. Let’s take a look at it now.

Tuples

Tuples are very similar to lists. The difference (and the reason for their existence) is that tuples are immutable. In other words, they can not be changed in place. Other than that everything we saw about lists also applies to tuples.

Tuples are defined by parentheses:

>>> t = (1, 2, 3)

>>> t[1]

2

>>> t[1:]

(2, 3)

Earlier we saw that strings know how to convert themselves to lists using their ’split’ method. We can also convert a string into a tuple with a function called tuple. It works like this:

>>> tuple('some string')

('s', 'o', 'm', 'e', ' ', 's', 't', 'r', 'i', 'n', 'g')

You may wonder when will you ever use tuples, since lists do everything tuples can do and more. Well, among other reasons, since tuples are immutable, they are handy whenever you want to make sure that they do not accidentally get changed by some call. Some built in operations require tuples. And last but not least, tuples make for excellent dictionary keys.

Dictionaries

Dictionaries allow us to collect all kinds of objects just as lists and tuples do. However, rather than fetching them back through the use of index or offset location, dictionaries allow us to fetch their items by keys. So, for each item in a dictionary, there is an accompanying key. Here is a dictionary example:

>>> d = {'key1': 'dog', 2: 'cat', ('key', 'number', 'three'): 'mouse'}

As you can see, dictionaries are enclosed in curly brackets ‘{}’, and each key-value pair is separated by a colon ‘:’. Notice that we can use strings ('key1'), numbers (2), and tuples (('key', 'number', 'three')) as dictionary keys. All of these are immutable type objects. Values can be anything we want: strings, lists, …, and even other dictionaries, which contain other dictionaries, that contain other…. Like lists, dictionaries can be modified in place. However, they are not ordered sequences so, as we said before, we can not use indexes or slices to retrieve their items. It is important to remember that the order in which dictionary items appear is not to be relied upon. Nevertheless, Python offers very simple ways to work with dictionaries. Let’s look at some examples.

Retrieving a value:

>>> d['key1']

'dog'

>>> d[2]

'cat'

Changing the value of a key:

>>> d['key1'] = ['milk', 'cake']

>>> d

{('key', 'number', 'three'): 'mouse', 2: 'cat', 'key1': ['milk', 'cake']}

Notice that on the last example the order of the dictionary items is printed differently than how we entered it. Now let’s add a new entry:

>>> d['new'] = 1.5

>>> d

{('key', 'number', 'three'): 'mouse', 2: 'cat', 'key1': ['milk', 'cake'], 'new': 1.5}

As with lists, to delete an item we can use the del function:

>>> del(d[('key', 'number', 'three')])

>>> d

{2: 'cat', 'key1': ['milk', 'cake'], 'new': 1.5}

Two very important operations that are frequently needed is the ability to retrieve all the keys or all the values contained in a dictionary. Python does this easily:

>>> d.keys()

[2, 'key1', 'new']

>>> d.values()

['cat', ['milk', 'cake'], 1.5]

Notice that in both instances Python returns a list of the items we requested. This is handy because we can then use any of the functions and methods associated with lists, such as sort and reverse, to arrange them in the order that we want. We could then iterate through each item in the right order, in spite of the fact that dictionaries are unordered collections. You may now wonder, what is to iterate? This brings us to our next major subject.

How to program in Python

In this section we are going to see how we can use the different data and object types that we have already covered, as well as a few others, to put together full scale programs.

Up to now all we have done is review some of the main object types available in Python using quick little one line expressions that do a single operation. However, the real power of computer programming is its ability to have the computer do multiple things for us with one simple command on our part. The concept of iteration is a good example of this.

Iteration is “the process of repeating a set of instructions a specified number of times or until a specific result is achieved. For example if we had a list with five items and we wanted to print each one of them, we could manually type five lines of code that would print each item. But what if we did not know how many items the list contained at any particular time, or what if the list contained hundreds of items? Well, actually the solution is very simple. This is how we would do it in Python:

“for” Loops

As we have seen already, lists can be of any length we desire. Lets see what we can do with a little list of 5 items.

>>> L = [1, 2, 3, 4, 5]

>>> for i in L:

…     print i

1

2

3

4

5

What we are doing is iterating through the list L, assigning a temporary variable named i (can be whatever you want) for each item in L, and printing it. Here is another example:

>>> students = ['John', 'Peter', 'Jeremy', 'Carly']

>>> for student in students:

…     print "You are a very good student, %s. " %(student)

…

You are a very good student, John.

You are a very good student, Peter.

You are a very good student, Jeremy.

You are a very good student, Carly.

This construct is called a for loop. It is the first compound statement that we look at. Notice that the first line, the header, of the loop terminates in a colon. Notice also that the second line of each of the two examples above, are indented. This is very important, as we will see later. The body of a for loop doesn’t have to be limited to one line. It can contain as many lines of commands as desired. It will execute all the commands of the body for each iteration, unless otherwise told in the code.

It is important to understand that the for loop is a sequence iterator. It can iterate through ordered sequence items, such as strings, lists, tuples, etc. This will carry you a long way in your programming needs. However, there is another way to iterate or repeat a series of commands. But before we see it, you need to understand another important concept.

“truth” Tests

In computer programming, certain expressions evaluate, to either truth or false. For example, we know that it is true that 5 is greater than 4. Python knows that too, and this is how Python expresses that:

>>> 5 > 4

1

As you can see, the expression 5 > 4 returned a value of 1. In programming, when evaluating the truthfulness of an expression, 1 is the common value for true and 0 is the common value for false. For example:

>>> 4 == 5

0

On this example you can see that to evaluate the equality of two values we used two equal signs rather than one. This is because, as we saw earlier, one equal sign is the assignment operator. So remember to use two equal signs when evaluating equality.

Besides math operations, Python recognizes other expressions as either true or false. For example, empty data types, like an empty string, list, etc, evaluate to false. There are also many operators that can be used inside a truth test expression. See the Python documentation for these if you are interested.

You will understand truth tests better by seeing them in action. So, let’s dive into our second method of iteration.

“while” Loops

A while loop repeats a set of commands until some terminating condition is met. They may never execute the body of the loop if the terminating condition is false to start with. Here is a basic example:

>>> x = 1

>>> while x < 10:

…     print x,

…     x = x + 1

1 2 3 4 5 6 7 8 9

Here you can see that the condition that we test for is whether x is less than 10. This little loop will continue repeating itself until that condition is false. You may also notice that by adding a comma at the end of a print statement it does not print a new line character after each print. So, all the numbers are printed in the same line.

One important lesson to remember with while loops is that, unless you want the loop to run forever, you should be sure that the condition will eventually be false. Let’s just look at another simple example to solidify your understanding:

>>> s = 'Something'

>>> while s:

…     print s,

…     s = s[1:]     # Removes the first character of the string

'Something' 'omething' 'mething' 'ething' 'thing' 'hing', 'ing', 'ng', 'g'

In this case, once the string is empty, the while loop stops because s evaluates to false.

So, as we can see, without truth tests while loops would not be possible. However, there is an even more basic programming feature where truth tests play a key role. With it we will be able to start adding real intelligence to our programs.

“if” Statements

The if statement allows our programs to select a course of action depending on whether or not a certain condition exists. The if statement is the third multi-line or compound statement that we look at. Let’s look at an example:

>>> if 5 > 4:

…     print "Life is good"

As in the previous compound statements, if statements have a header. The header begins with the if word itself followed by the expression that is to be evaluated, and ends with a colon. Again the body of the statement is indented.

Let’s look at a more realistic example:

>>> first_name = 'Bob'

>>> last_name = ''

>>> Greeting = 'Hello %s %s' % (first_name, last_name)

>>> if first_name and last_name:

…     print Greeting

In this example we can see that the Greeting would only be printed if both first_name and last_name evaluate to true. Since, in this case, last_name is an empty string it will evaluate to false, and the Greeting will not be printed. Python will simply continue to its next command outside of the body of the if statement. Let’s look at another example:

age = int(raw_input("How old are you? "))     #The int function returns its input as integer.

gender = raw_input("Are you male or female? ")

if age >= 13 and age <= 19:

    if gender.capitalize() == "Male":

        print "You are a teenage boy."

    else:

        print "You are a teenage girl."

The raw_input function allows us to get input from the user. If we type those commands in a file named test.py and ran it as a script from the Command Prompt (e.g.: ~\somedirectory>python test.py) we would get the following output:

How old are you? 15

Are you male or female? Male

You are a teenage boy.

Here we can see that if statements can be nested inside other if statements. The same is true for any other compound statement. You can nest compound statements as deep as you like. In this example we also see that an else statement can be used in conjunction with an if statement. An if/else combination allows the program to decide between two courses of action. Only one of the two will be executed. A similar construct is the elif statement (which stands for “else if”) which allows the program to choose from any number of ways to proceed depending on which condition is found to match first. For example:

>>> if day == "Saturday":

…     print "Happy day"

… elif day == "Sunday":

…     print "Weekend is almost over."

… elif month != "August":

…     print "Today is not an August weekend"

… elif hour > 22:

…     print "Time to go to bed"

… else:

…     print "Today is not a weekend, it is August and I still have time to do something"

With if statements we can give our programs many options to select from. It will check each one in order and select the first one that returns a true evaluation. Notice that the “not equal” operator (!=) returns a true evaluation if the Month variable is anything other than “August”. Something to watch out for in this kind of construct is that the “Time to go to bed” string will not get printed even if it is past 10:00 p.m., unless all the previous options were false. And finally, notice that we ended the sequence of statements with an else block. This one will get executed for sure once all the previous options proved false.

So, as you can see, truth tests in conjunction with if/elif/else statements can be very powerful in helping you express the logic of your program. The if statement is very often found inside while and for loops to change the flow of operation of the loop or to exit the loop if a certain condition is found. Let’s look at an example:

>>> L = ["mouse","", "cat", "dog", "parrot"]

>>> for animal in L:

…     if animal == "dog":

…         print "Dogs are not allowed"

…         break

…     elif animal == "":

…         pass

…     else:

…         print "What a nice %s you have" %(animal)

…

What a nice mouse you have

What a nice cat you have

Dogs are not allowed

The break statement is used to exit the current loop. If the loop of this example had been inside another loop, the break statement would have simply continued to the next iteration of the outer loop. The pass keyword simply tells Python to do nothing. Again, notice the all important use of indentation to correctly identify the end of nested statements.

What we have covered so far is enough for you to be able to write very rich and powerful programs. However, we have just touched the most basic elements of computer programming. There are a few more concepts to learn in order to take full advantage of what can be done in Python. We will look at them in Python for Newbies – Part 2.

Now we have some interesting news for you all

Here are the pictures showing N900 can be used in portrait mode too, So it seems like they have already implemented and now taking their time to make it work flawless on accelerometer

It just matter of weeks to get the portrait mode working.

Here is the video

http://share.ovi.com/media/Guyver95.PortraitMode/Guyver95.10009?sort=0

Source

Hi the N900 support page is finally online.Whats the support page brings us:
-User Manual in all languages
-How To which is used for basic tweaks you can do in N900
-Softwares from Nokia for your N900
-Accessories Available for your N900
-Specification
-Simple 400 FAQ’s

N900 Support Page

FM Transmitter Demo
Hi geeks we all know N900 sports a fm transmitter.The N900 fmtransmitter is demoed by Steffen, a member of the Maemo 5 UI Team.The Fm transmitter is basically used to transmit the audio from N900 to the nearby Fm receiver.Here in this below video you can see the working of it.

Hello folks,
The N900 running a linux os so there are many keyboard shortcuts available to us.Lets have a look of all the keyboard shortcuts and various light notification used in N900 for notifying and to start various process.
Notification lights colour:

1.Blue Color light is meant for Application notifications such as an IM or Text Or Email.

2.Orange Color light indicate the battery is getting charged

3.Green Light denotes Battery charge is full

Keyboard Shortcuts Inside the Applications:
1.Ctrl+Backspace takes you to taskmanager .
2.As Usual Ctrl + C for copy text ,Ctrl + V to paste text ,Ctrl + X and Ctrl + A for moving text .
3. Ctrl + O Used to open.
4. Ctrl + N: Used to create a new item .
5.Ctrl + S: Used to Save .
6.Ctrl + Z: Used to undo .
7.Ctrl + Y: Used to Redo .
8.Ctrl + F: Opens the search bar for searching .
9.Ctrl + Right arrow: Function as END key in pc move to the end of the word.
10.Ctrl + Left arrow: Function as HOME key in pc move to the beginning of the word.
11.Ctrl + Shift + P:Used to Capture the screen as image.
12.Ctrl + Shift + X: Opens ‘X Terminal’
Keyboard Shorcuts for Web Browser:
1.Ctrl + N: Opens a fresh window in browser
2.Ctrl + R:Reloads the current page also can be used to reload the feed in RSS Viewer
3.Ctrl + B:Opens the Bookmarks folder
4.Ctrl + D:Save a new bookmark of the opened site
5.Ctrl + S:Save the current page.
6.Circular Zoom:To zoom the webpage

Also 1.Volume Rocker can be also used to zoom.
2.Double tap can also used to zoom.
7.Press Space:To scroll one page down.
8.Press Shift + Space:To One Page up.
Email Shortcuts
1.Ctrl + Enter:To send the current composed email.
2.Ctrl + R:To open new window for sending the reply to the current reading mail.

Check Out Other Tips:
1.HowTo: Create a shortcut to a file on the N900’s desktop
2.HowTo: Browse the N900’s File-system using its Web-Browser
3.How to take the Red-Pill and install more apps on the N900

Thanks to Nokia Experts.

Being able create a file-shortcut on the desktop is a standard feature of all desktop environments like XP, GNOME, KDE, OS X etc. Unfortunately, the N900’s desktop doesn’t allow putting any kind of link on the desktop except if its a bookmark. So if you like having quick access to certain files from the desktop, there is a workaround through the browser.

In the following example, I will create a shortcut to the agenda.pdf file. Open the file-system from the browser (see my previous post) and navigate to the folder of the file’s location.

Press and hold on the filename to bring up the menu. Select Add Bookmark. Give it a name and Save.

This will create a bookmak to the file. Now add the bookmark on the desktop.

Thats it. The file can be launched directly from the desktop.

Not so nice parts of this hack:
Web-browser launches, bookmark-folder inflates with the links, and the shortcuts on the desktop are deceptive without the thumbnail.

created using MaStory on the N900

The N900’s Web-Browser can be used to browse its entire file-system. To list the root directory, enter file:/// in the web-address field.

File-System on the N900 Web-Browser

If you are looking for the home directory, enter file:///home/user/MyDocs/