# HG changeset patch # User Puneeth Chaganti # Date 1289372536 -19800 # Node ID 0840aa06d2e6a4659a8d3e877764b88e59422efd # Parent e62bc810999c568f5737fbd1624e4486af8640bf Parially cleaned up conditionals LO. diff -r e62bc810999c -r 0840aa06d2e6 conditionals/questions.rst --- a/conditionals/questions.rst Wed Nov 10 10:47:21 2010 +0530 +++ b/conditionals/questions.rst Wed Nov 10 12:32:16 2010 +0530 @@ -75,5 +75,6 @@ .. A minimum of 2 questions here (along with answers) -1. Question 1 -2. Question 2 +1. + +2. diff -r e62bc810999c -r 0840aa06d2e6 conditionals/script.rst --- a/conditionals/script.rst Wed Nov 10 10:47:21 2010 +0530 +++ b/conditionals/script.rst Wed Nov 10 12:32:16 2010 +0530 @@ -1,14 +1,20 @@ .. Objectives .. ---------- -.. Clearly state the objectives of the LO (along with RBT level) +.. By the end of this tutorial, you will be able to + +.. * Use if/else blocks +.. * Use if/elif/else blocks +.. * Use the Ternary conditional statement - C if X else Y + +.. to check conditions in your programs. + .. Prerequisites .. ------------- -.. 1. Name of LO-1 -.. 2. Name of LO-2 -.. 3. Name of LO-3 +.. 1. Basic datatypes and operators + .. Author : Madhu Internal Reviewer : @@ -21,8 +27,7 @@ {{{ Show the slide containing the title }}} -Hello friends. Welcome to this spoken tutorial on Getting started with -strings. +Hello friends. Welcome to this spoken tutorial on Conditionals {{{ Show the slide containing the outline }}} @@ -40,10 +45,12 @@ Whenever we have two possible states that can occur depending on a whether a certain condition we can use if/else construct in -Python. Say for example we have a variable "a" which stores integers -and we are required to find out whether the value of the variable "a" -is an even number or an odd number. To test out conditional statements -as an example, let us say the value of the variable "a" is 5:: +Python. + +For example, say, we have a variable ``a`` which stores integers and +we are required to find out whether ``a`` is even or odd. an even +number or an odd number. Let's say the value of ``a`` is 5, now. +:: a = 5 @@ -54,36 +61,29 @@ else: print "Odd" -When the value of the variable "a" is divided by 2 and the remainder -is 0 i.e. the result of the operation "a modulo 2" is 0 the condition -"a % 2 == 0" evaluates to True, so the code within the if block gets -executed. This means that the value of "a" is Even. +If ``a`` is divisible by 2, i.e., the result of "a modulo 2" is 0, it +prints "Even", otherwise it prints "Odd". + +Note that in such a case, only one of the two blocks gets executed +depending on whether the condition is ``True`` or ``False``. -If the operation "a modulo 2" is not 0 the condition "a % 2 == 0" -evaluates to False and hence the code block within else gets executed -which means that the value of "a" is Odd. - -Note in such a case only one of the two blocks get executed depending -on whether the condition is True or False. +There is a very important sytactic element to understand here. Every +code block begins with a line that ends with a ``:``, in this example +the ``if`` and the ``else`` lines. Also, all the statements inside a +code block are intended by 4 spaces. Returning to the previous +indentation level, ends the code block. -There is a very important sytactic element to understand here. All the -statements which are inside a certain code block are indented by 4 -spaces. The statement which starts a new code block after it, i.e. the -if statement in this example ends with a colon (:). So the next -immediate line will be inside the if block and hence indented by 4 -spaces. To come out of the code block we have to come back to the -previous indentation level as shown in the else line here. Again the -line following else will be in a new block so else line ends with a -colon and the following block of code is indented by 4. +The if/else blocks work for a condition, which can take one of two +states. What do we do for conditions, which can take more than two +states? -As we use if/else statement when we have a condition which can take -one of the two states, we may have conditions which can take more than -two states. In such a scenario Python provides if/elif/else -statements. Let us take an example. We have a variable "a" which holds -integer values. We need to print "positive" if the value of a is -positive, "negative" if it is negative and "zero" if the value of the -variable "a" is 0. Let us use if/elif/else ladder for it. For the -purposes of testing our code let us assume that the value of a is -3:: +Python provides if/elif/else blocks, for such conditions. Let us take +an example. We have a variable ``a`` which holds integer values. We +need to print "positive" if ``a`` is positive, "negative" if +it is negative or "zero" if it is 0. + +Let us use if/elif/else ladder for it. For the purposes of testing our +code let us assume that the value of a is -3:: a = -3 @@ -94,18 +94,18 @@ else: print "zero" -This if/elif/else ladder is self explanatory. All the syntax and rules -as said for if/else statements hold. The only addition here is the -elif statement which can have another condition of its own. +All the syntax and rules as said for if/else statements hold. The only +addition here is the ``elif`` statement which can have another +condition of its own. -Here, exactly one block of code is executed and that block of code -corresponds to the condition which first evaluates to True. Even if -there is a situation where multiple conditions evaluate to True all -the subsequent conditions other than the first one which evaluates to -True are neglected. Consequently, the else block gets executed if and -only if all the conditions evaluate to False. +Here too, exactly one block of code is executed -- the block of code +which first evaluates to ``True``. Even if there is a situation where +multiple conditions evaluate to True all the subsequent conditions +other than the first one which evaluates to True are neglected. +Consequently, the else block gets executed if and only if all the +conditions evaluate to False. -Also, the else block in both if/else statement and if/elif/else is +Also, the ``else`` block in both if/else statement and if/elif/else is optional. We can have a single if statement or just if/elif statements without having else block at all. Also, there can be any number of elif's within an if/elif/else ladder. For example @@ -124,6 +124,12 @@ is completely valid. Note that there are multiple elif blocks and there is no else block. +Following is an exercise that you must do. + +%% %% + +Please, pause the video here. Do the exercise and then continue. + In addition to these conditional statements, Python provides a very convenient ternary conditional operator. Let us take the following example where we read the marks data from a data file which is @@ -147,10 +153,16 @@ it is 0. This means that we make the scores of the students who were absent for the exam 0. -Moving on, there are certain situations where we will have to no -operations or statements within the block of code. For example, we -have a code where we are waiting for the keyboard input. If the user -enters "s" as the input we would perform some operation nothing +Following is an exercise that you must do. + +%% %% + +Please, pause the video here. Do the exercise and then continue. + +Moving on, there are certain situations where we will have no +operations or statements within a block of code. For example, we have +a code where we are waiting for the keyboard input. If the user enters +"c", "d" or "x" as the input we would perform some operation nothing otherwise. In such cases "pass" statement comes very handy:: a = raw_input("Enter 'c' to calculate and exit, 'd' to display the existing @@ -167,8 +179,7 @@ In this case "pass" statement acts as a place holder for the block of code. It is equivalent to a null operation. It literally does -nothing. So "pass" statement can be used as a null operation -statement, or it can used as a place holder when the actual code +nothing. It can used as a place holder when the actual code implementation for a particular block of code is not known yet but has to be filled up later. diff -r e62bc810999c -r 0840aa06d2e6 conditionals/slides.org --- a/conditionals/slides.org Wed Nov 10 10:47:21 2010 +0530 +++ b/conditionals/slides.org Wed Nov 10 12:32:16 2010 +0530 @@ -18,7 +18,7 @@ #+LaTeX_HEADER: commentstyle=\color{red}\itshape, stringstyle=\color{darkgreen}, #+LaTeX_HEADER: showstringspaces=false, keywordstyle=\color{blue}\bfseries} -#+TITLE: Accessing parts of arrays +#+TITLE: Conditionals #+AUTHOR: FOSSEE #+EMAIL: #+DATE: @@ -30,81 +30,26 @@ #+OPTIONS: TeX:t LaTeX:nil skip:nil d:nil todo:nil pri:nil tags:not-in-toc * Outline - - Manipulating one and multi dimensional arrays - - Access and change individual elements - - Access and change rows and columns - - Slicing and striding on arrays to access chunks - - Read images into arrays and manipulations -* Sample Arrays - #+begin_src python - In []: A = array([12, 23, 34, 45, 56]) - - In []: C = array([[11, 12, 13, 14, 15], - [21, 22, 23, 24, 25], - [31, 32, 33, 34, 35], - [41, 42, 43, 44, 45], - [51, 52, 53, 54, 55]]) - - #+end_src + * Question 1 - Change the last column of ~C~ to zeroes. + * Solution 1 #+begin_src python - In []: C[:, -1] = 0 - #+end_src -* Question 2 - Change ~A~ to ~[11, 12, 13, 14, 15]~. -* Solution 2 - #+begin_src python - In []: A[:] = [11, 12, 13, 14, 15] - #+end_src -* squares.png - #+begin_latex - \begin{center} - \includegraphics[scale=0.6]{squares} - \end{center} - #+end_latex -* Question 3 - - obtain ~[22, 23]~ from ~C~. - - obtain ~[11, 21, 31, 41]~ from ~C~. - - obtain ~[21, 31, 41, 0]~. -* Solution 3 - #+begin_src python - In []: C[1, 1:3] - In []: C[0:4, 0] - In []: C[1:5, 0] - #+end_src -* Question 4 - Obtain ~[[23, 24], [33, -34]]~ from ~C~ -* Solution 4 - #+begin_src python - In []: C[1:3, 2:4] - #+end_src -* Question 5 - Obtain the square in the center of the image -* Solution 5 - #+begin_src python - In []: imshow(I[75:225, 75:225]) - #+end_src -* Question 6 - Obtain the following - #+begin_src python - [[12, 0], [42, 0]] - [[12, 13, 14], [0, 0, 0]] + #+end_src -* Solution 6 +* ~if/elif~ ladder #+begin_src python - In []: C[::3, 1::3] - In []: C[::4, 1:4] + if user == 'admin': + # Do admin operations + elif user == 'moderator': + # Do moderator operations + elif user == 'client': + # Do customer operations #+end_src + * Summary - You should now be able to -- - - Manipulate 1D \& Multi dimensional arrays - - Access and change individual elements - - Access and change rows and columns - - Slice and stride on arrays - - Read images into arrays and manipulate them. + * Thank you! #+begin_latex \begin{block}{} diff -r e62bc810999c -r 0840aa06d2e6 progress.org --- a/progress.org Wed Nov 10 10:47:21 2010 +0530 +++ b/progress.org Wed Nov 10 12:32:16 2010 +0530 @@ -34,8 +34,8 @@ | 5.5 LO: | Assessment | 3 | Anoop | | | |---------+----------------------------------------+-------+----------+-----------------+-----------| | 6.1 LO: | basic datatypes & operators | 4 | Amit | Punch (Done) | | -| 6.2 LO: | I/O | 1 | Nishanth | Amit(Done) | | -| 6.3 LO: | conditionals | 2 | Madhu | | | +| 6.2 LO: | I/O | 1 | Nishanth | Amit (Done) | | +| 6.3 LO: | conditionals | 2 | Madhu | Punch (Pending) | | | 6.4 LO: | loops | 2 | Punch | Anoop (Done) | | | 6.5 LO: | Assessment | 3 | Anoop | | | |---------+----------------------------------------+-------+----------+-----------------+-----------| diff -r e62bc810999c -r 0840aa06d2e6 progress.org.orig --- a/progress.org.orig Wed Nov 10 10:47:21 2010 +0530 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,55 +0,0 @@ -| S.No | Name | Units | Author | Review | Checklist | -|---------+----------------------------------------+-------+----------+---------------------------------------+-----------| -| 1.2 LO: | getting started with =ipython= | 2 | Punch | Anoop (Done) | | -| 1.3 LO: | using the =plot= command interactively | 2 | Amit | | | -| 1.4 LO: | embellishing a plot | 2 | Nishanth | Anoop (Done) | | -| 1.5 LO: | saving plots | 2 | Anoop | | | -| 1.6 LO: | multiple plots | 3 | Madhu | Nishanth (Done) | | -| 1.7 LO: | additional features of IPython | 2 | Nishanth | Amit (Pending) | | -| 1.8 LO: | module level assessment | 3 | Madhu | | | -|---------+----------------------------------------+-------+----------+---------------------------------------+-----------| -| 2.2 LO: | loading data from files | 3 | Punch | Nishanth (Done) | | -| 2.3 LO: | plotting the data | 3 | Amit | | | -| 2.4 LO: | other types of plots | 3 | Anoop | Pending | | -| 2.5 LO: | module level assessment | 3 | Nishanth | | | -|---------+----------------------------------------+-------+----------+---------------------------------------+-----------| -| 3.1 LO: | getting started with lists | 2 | Amit | | | -| 3.2 LO: | getting started with =for= | 2 | Anoop | Nishanth (Done) | | -| 3.3 LO: | getting started with strings | 2 | Madhu | | | -| 3.4 LO: | getting started with files | 3 | Punch | Anoop(Done) | | -| 3.5 LO: | parsing data | 3 | Nishanth | Amit (Done) | | -| 3.6 LO: | statistics | 2 | Amit | | | -| 3.7 LO: | module level assessment | 3 | Madhu | | | -|---------+----------------------------------------+-------+----------+---------------------------------------+-----------| -| 4.1 LO: | getting started with arrays | 2 | Anoop | Punch (Done) | | -| 4.2 LO: | accessing parts of arrays | 4 | Punch | Anoop (Done) | | -| 4.3 LO: | Matrices | 3 | Anoop | Punch (changes before further review) | | -| 4.4 LO: | Least square fit | 2 | Nishanth | Punch (Done) | | -| 4.5 LO: | Assessment | 3 | Punch | | | -|---------+----------------------------------------+-------+----------+---------------------------------------+-----------| -| 5.1 LO: | getting started with sage notebook | 3 | Madhu | | | -| 5.2 LO: | getting started with symbolics | 3 | Amit | | | -| 5.3 LO: | using Sage | 4 | Punch | Anoop (Pending) | | -| 5.4 LO: | using sage to teach | 3 | Nishanth | | | -| 5.5 LO: | Assessment | 3 | Anoop | | | -|---------+----------------------------------------+-------+----------+---------------------------------------+-----------| -| 6.1 LO: | basic datatypes & operators | 4 | Amit | Punch (Done) | | -| 6.2 LO: | I/O | 1 | Nishanth | | | -| 6.3 LO: | conditionals | 2 | Madhu | | | -| 6.4 LO: | loops | 2 | Puneeth | Anoop(Pending) | | -| 6.5 LO: | Assessment | 3 | Anoop | | | -|---------+----------------------------------------+-------+----------+---------------------------------------+-----------| -| 7.1 LO: | manipulating lists | 3 | Madhu | | | -| 7.2 LO: | manipulating strings | 2 | Punch | Anoop | Amit | -| 7.3 LO: | getting started with tuples | 2 | Nishanth | | | -| 7.4 LO: | dictionaries | 2 | Anoop | Pending | | -| 7.5 LO: | sets | 2 | Nishanth | | | -| 7.6 LO: | Assessment | 3 | Amit | | | -|---------+----------------------------------------+-------+----------+---------------------------------------+-----------| -| 8.1 LO: | getting started with functions | 3 | Nishanth | | | -| 8.2 LO: | advanced features of functions | 3 | Punch | Anoop (Pending) | | -| 8.3 LO: | using python modules | 3 | Anoop | Pending | | -| 8.4 LO: | writing python scripts | 2 | Nishanth | | | -| 8.5 LO: | testing and debugging | 2 | Amit | | | -| 8.6 LO: | Assessment | 3 | Madhu | | | -|---------+----------------------------------------+-------+----------+---------------------------------------+-----------|