--- a/accessing-pieces-arrays/questions.rst Thu Oct 07 10:07:22 2010 +0530
+++ b/accessing-pieces-arrays/questions.rst Thu Oct 07 10:08:19 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.]
+
+
+