# HG changeset patch
# User Puneeth Chaganti <punchagan@fossee.in>
# Date 1286371597 -19800
# Node ID 4e0cdb5cca53cca7ccd4ba1113da790c991340c7
# Parent  ce0e8c99eaee951a572d331441067607d9dd9213
Added questions and other info to accessing-pieces-arrays LO.

diff -r ce0e8c99eaee -r 4e0cdb5cca53 accessing-pieces-arrays/questions.rst
--- a/accessing-pieces-arrays/questions.rst	Wed Oct 06 17:31:20 2010 +0530
+++ b/accessing-pieces-arrays/questions.rst	Wed Oct 06 18:56:37 2010 +0530
@@ -1,17 +1,159 @@
-Objective
----------
+Objective Questions
+-------------------
+
+.. A mininum of 8 questions here (along with answers)
+
+1. Given the array, ``A = array([12, 15, 18, 21])``, how do we access
+   the element ``18``?
+
+   Answer: ``A[2]``
+
+#. Given the array, ``A = array([12, 15, 18, 21])``, what element is
+   accessed by ``A[1]``
+
+   Answer: ``15``  
+
+#. Given the array, ``A = array([12, 15, 18, 21])``, what element is
+   accessed by ``A[-3]``?
+
+   Answer: ``15``  
+
+#. Given the array, ``A = array([12, 15, 18, 21])``, how do you change
+   the element ``15`` to ``51``?
+
+   Answer: ``A[1] = 51``
 
-.. A mininum of 8 questions here. 
+#. Given the array, ``A = array([12, 15, 18, 21])``, what is ``A``
+   after the execution of the statement ``A[3] = 24``?
+
+   Answer: ``array([12, 15, 18, 24])``
+
+#. Given the array, ``A = array([12, 15, 18, 21])``, what is the
+   result of the statement, ``A[4] = 24``?
+
+   Answer: IndexError: index out of bounds
+
+#. Given the array, ``B = array([[12, 15], [18, 21]])``, how do we
+   access the element ``18``? 
+
+   Answer: ``A[0, 0]``
+
+#. Given the array, ``B = array([[12, 15], [18, 21]])``, what is the
+   result of ``B[1]``? 
+
+   Answer:  ``array([18, 21])``
+
+#. Given the array, ``B = array([[12, 15], [18, 21]])``, what is the
+   result of ``B[1, 1]``?
+
+   Answer:  ``21``
+
+#. Given the array, ``B = array([[12, 15], [18, 21]])``, what element
+   is accessed by ``B[-1, -2]``?
 
-1. Question 1
-2. Question 2
-3. Question 3
+   Answer:  ``18``   
+
+#. Given the array, ``B = array([[12, 15], [18, 21]])``, how do you
+   change the element ``15`` to ``51``?
+
+   Answer:  ``B[0, 1] = 51``   
+
+#. Given the array, ``B = array([[12, 15], [18, 21]])``, what is the
+   value of B, after executing, ``B[0] = 0``?
+
+   Answer:  ``array([[0, 0], [18, 21]])``   
+
+#. Given the array, 
+   
+   ::
+   
+     B = array([[10, 11, 12, 13],
+                [20, 21, 22, 23],
+                [30, 31, 32, 33],
+                [40, 41, 42, 43]])
+
+   Obtain the elements, ``[[21, 22], [32, 32]]``
+
+   Answer:  ``B[1:3, 1:3]``   
 
+#. Given the array, 
+   
+   ::
+   
+     B = array([[10, 11, 12, 13],
+                [20, 21, 22, 23],
+                [30, 31, 32, 33],
+                [40, 41, 42, 43]])
 
+   Obtain the elements, ``[[10, 13], [30, 33]]``
+
+   Answer:  ``B[::2, ::3]``
+
+#. What command is used to read an image file?
+
+   a. imshow
+   #. imread
+   #. imopen
+   #. open
+
+   Answer: ``imread``   
+
+#. If ``P`` is ``array([12, 13, 14, 15])`` then ``P.shape`` gives
+   ``(4, 1)``. True or False?
+
+   Answer: False
+     
 Larger Questions
 ----------------
 
-.. A minimum of 2 questions here. 
+.. A minimum of 2 questions here (along with answers)
+
+1. Given the array, 
+   ::
+   
+     B = array([[10, 11, 12, 13],
+                [20, 21, 22, 23],
+                [30, 31, 32, 33],
+                [40, 41, 42, 43]])
+
+   Change the array to 
+   ::
+   
+     B = array([[10, 11, 10, 11],
+                [20, 21, 20, 21],
+                [10, 11, 10, 11],
+                [20, 21, 20, 21]])
+
+   using slicing and striding. 
+
+   Answer::
+
+     B[:2, 2:] = B[:2, :2]
+     B[2:, :2] = B[:2, :2]
+     B[2:, 2:] = B[:2, :2]
 
-1. Programming Assignment 1
-2. Programming Assignment 2
+#. Find out how to display a grayscale image with proper colors. Hint,
+   use ``?`` on ``imshow``. 
+   
+   Answer: ``cmap=cm.gray``
+                  
+#. From the image, ``tagore-einstein.png``, 
+   a. show only the face of Einstein. 
+   b. show only the face of Tagore. 
+
+   Hint, use ``imread`` to read the image and ``imshow`` to show the
+   image.  Use ``cm.gray`` as ``cmap`` to display the image properly.   
+
+   Answer:: 
+
+     F = imread('tagore-einstein.png')
+     imshow(F[:210, 20:180], cmap=cm.gray)
+
+     F = imread('tagore-einstein.png')
+     imshow(F[30:300, 320:480], cmap=cm.gray)
+
+.. #[Puneeth: This question contains answer to previous
+.. question. Shouldn't be shown at the same time.]
+
+
+          
diff -r ce0e8c99eaee -r 4e0cdb5cca53 accessing-pieces-arrays/script.rst
--- a/accessing-pieces-arrays/script.rst	Wed Oct 06 17:31:20 2010 +0530
+++ b/accessing-pieces-arrays/script.rst	Wed Oct 06 18:56:37 2010 +0530
@@ -1,7 +1,15 @@
 .. Objectives
 .. ----------
-
-.. Clearly state the objectives of the LO (along with RBT level)
+   
+   By the end of this tutorial, you will be able to:
+   
+     1. Access and change individual elements of arrays, both one
+     dimensional and multi-dimensional.
+     2. Access and change rows and columns of arrays. 
+     3. Access and change other chunks from an array, using slicing
+     and striding. 
+     4. Read images into arrays and perform processing on them, using
+     simple array manipulations. 
 
 .. Prerequisites
 .. -------------
@@ -18,7 +26,6 @@
 Script
 ------
 
-
 {{{ Screen shows welcome slide }}}
 
 Welcome to the tutorial on accessing pieces of arrays
diff -r ce0e8c99eaee -r 4e0cdb5cca53 accessing-pieces-arrays/tagore-einstein.png
Binary file accessing-pieces-arrays/tagore-einstein.png has changed