diff -r 975677bf1b8a -r e62bc810999c getting-started-strings/slides.org --- a/getting-started-strings/slides.org Wed Nov 10 10:24:03 2010 +0530 +++ b/getting-started-strings/slides.org Wed Nov 10 10:47:21 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: #+AUTHOR: FOSSEE #+EMAIL: #+DATE: @@ -30,81 +30,38 @@ #+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 +*** Defining strings +*** Concatenation +*** Accessing individual elements +*** Immutability of strings * Question 1 - Change the last column of ~C~ to zeroes. + Obtain the string ~%% -------------------- %%~ (20 hyphens) without + typing out all the twenty hyphens. * Solution 1 #+begin_src python - In []: C[:, -1] = 0 + s = "%% " + "-"*20 + " %%" #+end_src * Question 2 - Change ~A~ to ~[11, 12, 13, 14, 15]~. + Given a string, ~s~ which is ~Hello World~ , what is the output of:: + #+begin_src python + s[-5] + s[-10] + s[-15] + #+end_src * 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 - #+begin_src python - In []: C[::3, 1::3] - In []: C[::4, 1:4] + 'W' + 'e' + IndexError #+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. + In this tutorial we have learnt + + How to define strings + + Different ways of defining a string + + String concatenation and repetition + + Accessing individual elements of the string + + Immutability of strings + * Thank you! #+begin_latex \begin{block}{}