accessing-pieces-arrays/slides.org.orig
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    16 
       
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    20 
       
    21 #+TITLE:    Accessing parts of arrays
       
    22 #+AUTHOR:    FOSSEE
       
    23 #+EMAIL:     
       
    24 #+DATE:    
       
    25 
       
    26 #+DESCRIPTION: 
       
    27 #+KEYWORDS: 
       
    28 #+LANGUAGE:  en
       
    29 #+OPTIONS:   H:3 num:nil toc:nil \n:nil @:t ::t |:t ^:t -:t f:t *:t <:t
       
    30 #+OPTIONS:   TeX:t LaTeX:nil skip:nil d:nil todo:nil pri:nil tags:not-in-toc
       
    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 single \& 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 * Thank you!
       
   109 #+begin_latex
       
   110   \begin{block}{}
       
   111   \begin{center}
       
   112   This spoken tutorial has been produced by the
       
   113   \textcolor{blue}{FOSSEE} team, which is funded by the 
       
   114   \end{center}
       
   115   \begin{center}
       
   116     \textcolor{blue}{National Mission on Education through \\
       
   117       Information \& Communication Technology \\ 
       
   118       MHRD, Govt. of India}.
       
   119   \end{center}  
       
   120   \end{block}
       
   121 #+end_latex
       
   122 
       
   123