st-scripts: comparison getting-started-with-functions/slides.org

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+#+LaTeX_CLASS: beamer
+#+LaTeX_CLASS_OPTIONS: [presentation]
+#+BEAMER_FRAME_LEVEL: 1
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+#+LaTeX_CLASS: beamer
+#+LaTeX_CLASS_OPTIONS: [presentation]
+#+LaTeX_HEADER: \usepackage[english]{babel} \usepackage{ae,aecompl}
+#+LaTeX_HEADER: \usepackage{mathpazo,courier,euler} \usepackage[scaled=.95]{helvet}
+#+LaTeX_HEADER: \usepackage{listings}
+#+LaTeX_HEADER:\lstset{language=Python, basicstyle=\ttfamily\bfseries,
+#+LaTeX_HEADER:  commentstyle=\color{red}\itshape, stringstyle=\color{darkgreen},
+#+LaTeX_HEADER:  showstringspaces=false, keywordstyle=\color{blue}\bfseries}
+#+TITLE:  Getting started with functions
+#+AUTHOR:  FOSSEE
+#+EMAIL:   info@fossee.in
+#+DATE:
+#+DESCRIPTION:
+#+KEYWORDS:
+#+LANGUAGE:  en
+#+OPTIONS:   H:3 num:nil toc:nil \n:nil @:t ::t |:t ^:t -:t f:t *:t <:t
+#+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
+# * Question 1
+#   Change the last column of ~C~ to zeroes.
+# * Solution 1
+#   #+begin_src python
+#     In []:  C[:, -1] = 0
+#   #+end_src
+# * Question 2
+#   Change ~A~ to ~[11, 12, 13, 14, 15]~.
+# * 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]
+#   #+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.
+* Outline
+- Define functions
+- Pass arguments to functions
+- Learn about docstrings
+- Return values from functions
+* Function
+- Eliminate code redundancy
+- Help in code reuse
+- Subroutine
+- relatively independent of remaining code
+* ~f(x)~ a mathematical function
+$f(x) = x^{2}$
+: f(1) -> 1
+: f(2) -> 4
+* Define ~f(x)~ in Python
+#+begin_src python
+def f(x):
+return x*x
+#+end_src
+- ~def~ - keyword
+- ~f~ - function name
+- ~x~ - parameter / argument to function ~f~
+* Exercise 1
+Write a python function named ~cube~ which computes the cube of a given
+number ~n~.
+- Pause here and try to solve the problem yourself.
+* Solution
+#+begin_src python
+def cube(n):
+	return n**3
+#+end_src
+* ~greet~ function
+Function ~greet~ which will print ~Hello World!~.
+#+begin_src python
+def greet():
+	print "Hello World!"
+#+end_src
+- Call the function ~greet~
+: In []: greet()
+: Hello World!
+* Exercise 2
+Write a python function named ~avg~ which computes the average of
+~a~ and ~b~.
+- Pause here and try to solve the problem yourself.
+* Solution 2
+#+begin_src python
+def avg(a,b):
+	return (a + b)/2
+#+end_src
+- ~a~ and ~b~ are parameters
+- ~def f(p1, p2, p3, ... , pn)~
+* Docstring
+- Documenting/commenting code is a good practice
+#+begin_src python
+def avg(a,b):
+""" avg takes two numbers as input
+	 (a & b), and returns the average
+	 of a and b"""
+	 return (a+b)/2
+#+end_src
+- Docstring
+- written in the line after the ~def~ line.
+- Inside triple quote.
+- Documentation
+: avg?
+* Exercise 3
+Add docstring to the function f.
+* Solution 3
+#+begin_src python
+def f(x):
+"""Accepts a number x as argument and,
+returns the square of the number x."""
+return x*x
+#+end_src
+* Exercise 4
+Write a python function named ~circle~ which returns the area and
+perimeter of a circle given radius ~r~.
+* Solution 4
+#+begin_src python
+def circle(r):
+"""returns area and perimeter of a circle given
+radius r"""
+pi = 3.14
+area = pi * r * r
+perimeter = 2 * pi * r
+return area, perimeter
+#+end_src
+* ~what~
+#+begin_src python
+def what( n ):
+if n < 0: n = -n
+while n > 0:
+if n % 2 == 1:
+return False
+n /= 10
+return True
+#+end_src
+* ~even_digits~
+#+begin_src python
+def even_digits( n ):
+"""returns True if all the digits of number
+n is even returns False if all the digits
+of number n is not even"""
+if n < 0: n = -n
+while n > 0:
+if n % 2 == 1:
+return False
+n /= 10
+return True
+#+end_src
+* ~what~
+#+begin_src python
+def what( n ):
+i = 1
+while i * i < n:
+i += 1
+return i * i == n, i
+#+end_src
+* ~is_perfect_square~
+#+begin_src python
+def is_perfect_square( n ):
+"""returns True and square root of n,
+if n is a perfect square, otherwise
+returns False and the square root
+of the next perfect square"""
+i = 1
+while i * i < n:
+i += 1
+return i * i == n, i
+#+end_src
+* Summary
+- Functions in Python
+- Passing parameters to a function
+- Returning values from a function
+- We also did few code reading exercises.
+* Thank you!
+#+begin_latex
+\begin{block}{}
+\begin{center}
+This spoken tutorial has been produced by the
+\textcolor{blue}{FOSSEE} team, which is funded by the
+\end{center}
+\begin{center}
+\textcolor{blue}{National Mission on Education through \\
+Information \& Communication Technology \\
+MHRD, Govt. of India}.
+\end{center}
+\end{block}
+#+end_latex

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