31 

    32 # * Outline

    33 #   - Manipulating one and multi dimensional arrays

    34 #   - Access and change individual elements 

    35 #   - Access and change rows and columns 

    36 #   - Slicing and striding on arrays to access chunks 

    37 #   - Read images into arrays and manipulations

    38 # * Sample Arrays

    39 #   #+begin_src python

    40 #     In []: A = array([12, 23, 34, 45, 56])

    41     

    42 #     In []: C = array([[11, 12, 13, 14, 15],

    43 #                       [21, 22, 23, 24, 25],

    44 #                       [31, 32, 33, 34, 35],

    45 #                       [41, 42, 43, 44, 45],

    46 #                       [51, 52, 53, 54, 55]])

    47     

    48 #   #+end_src

    49 # * Question 1

    50 #   Change the last column of ~C~ to zeroes. 

    51 # * Solution 1

    52 #   #+begin_src python

    53 #     In []:  C[:, -1] = 0

    54 #   #+end_src

    55 # * Question 2

    56 #   Change ~A~ to ~[11, 12, 13, 14, 15]~. 

    57 # * Solution 2

    58 #   #+begin_src python

    59 #     In []:  A[:] = [11, 12, 13, 14, 15]

    60 #   #+end_src

    61 # * squares.png

    62 #   #+begin_latex

    63 #     \begin{center}

    64 #       \includegraphics[scale=0.6]{squares}    

    65 #     \end{center}

    66 #   #+end_latex

    67 # * Question 3

    68 #   - obtain ~[22, 23]~ from ~C~. 

    69 #   - obtain ~[11, 21, 31, 41]~ from ~C~. 

    70 #   - obtain ~[21, 31, 41, 0]~.   

    71 # * Solution 3

    72 #   #+begin_src python

    73 #     In []:  C[1, 1:3]

    74 #     In []:  C[0:4, 0]

    75 #     In []:  C[1:5, 0]

    76 #   #+end_src

    77 # * Question 4

    78 #   Obtain ~[[23, 24], [33, -34]]~ from ~C~

    79 # * Solution 4

    80 #   #+begin_src python

    81 #     In []:  C[1:3, 2:4]

    82 #   #+end_src

    83 # * Question 5

    84 #   Obtain the square in the center of the image

    85 # * Solution 5

    86 #   #+begin_src python

    87 #     In []: imshow(I[75:225, 75:225])

    88 #   #+end_src

    89 # * Question 6

    90 #   Obtain the following

    91 #   #+begin_src python

    92 #     [[12, 0], [42, 0]]

    93 #     [[12, 13, 14], [0, 0, 0]]

    94 #   #+end_src

    95 

    96 # * Solution 6

    97 #   #+begin_src python

    98 #     In []: C[::3, 1::3]

    99 #     In []: C[::4, 1:4]

   100 #   #+end_src

   101 # * Summary

   102 #   You should now be able to --

   103 #   - Manipulate 1D \& Multi dimensional arrays

   104 #       - Access and change individual elements 

   105 #       - Access and change rows and columns 

   106 #       - Slice and stride on arrays

   107 #   - Read images into arrays and manipulate them.

   108