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\documentclass[14pt,compress,aspectratio=169]{beamer}
\input{macros.tex}
\title[Practice advanced functions]{Advanced Python}
\subtitle{Practice advanced functions}
\author[FOSSEE] {The FOSSEE Group}
\institute[IIT Bombay] {Department of Aerospace Engineering\\IIT Bombay}
\date[] {Mumbai, India}
\begin{document}
\begin{frame}
\titlepage
\end{frame}
\begin{frame}[plain, fragile]
\frametitle{Exercise: product of all arguments}
\begin{block}{}
Write a function called \lstinline{prod} that can be called with any
number of arguments (at least one) but computes the product of all the
given values as seen below.
\end{block}
\begin{lstlisting}
In []: prod(2., 2.)
Out[]: 4.0
In []: prod(1, 2, 3)
Out[]: 6
\end{lstlisting}
\end{frame}
\begin{frame}[plain, fragile]
\frametitle{Solution}
\begin{lstlisting}
def prod(*args):
res = 1.0
for x in args:
res *= x
return res
\end{lstlisting}
\end{frame}
\begin{frame}[plain, fragile]
\frametitle{Another solution}
\begin{lstlisting}
def prod(*args):
res = args[0]
for i in range(1, len(args)):
res *= args[i]
return res
\end{lstlisting}
\end{frame}
\begin{frame}[plain, fragile]
\frametitle{Exercise: function applied to arguments}
\begin{block}{}
Write a function called \lstinline{apply} which takes a function followed
by an arbitrary number of arguments and returns a list with the function
applied to all the arguments as shown below.
\end{block}
\begin{lstlisting}
In []: def twice(x):
...: return x*2
In []: apply(twice, 1, 2)
Out[]: [2, 4]
In []: apply(twice, 1, 2, 3)
Out[]: [2, 4, 6]
\end{lstlisting}
\end{frame}
\begin{frame}[plain, fragile]
\frametitle{Solution}
\begin{lstlisting}
def apply(f, *args):
result = []
for arg in args:
result.append(f(arg))
return result
\end{lstlisting}
\end{frame}
\begin{frame}[plain, fragile]
\frametitle{Exercise: number of kwargs}
\begin{block}{}
Write a function \lstinline{nkw} that takes an arbitrary number of
keyword arguments and returns the number of keyword arguments passed.
\end{block}
\begin{lstlisting}
In []: nkw(x=1, y=2)
Out[]: 2
In []: nkw()
Out[]: 0
In []: nkw(x=1)
Out[]: 1
\end{lstlisting}
\end{frame}
\begin{frame}[plain, fragile]
\frametitle{Solution}
\begin{lstlisting}
def nkw(**kw):
return len(kw)
\end{lstlisting}
\end{frame}
\begin{frame}[plain, fragile]
\frametitle{Exercise: name of kwargs}
\begin{block}{}
Write a function \lstinline{kwname} that takes an arbitrary number of
keyword arguments and returns a sorted list of the keyword arguments
passed.
\end{block}
\begin{lstlisting}
In []: kwname(x=1, y=2)
Out[]: ['x', 'y']
In []: kwname()
Out[]: []
In []: kwname(z=1, a=2)
Out[]: ['a', 'z']
\end{lstlisting}
\end{frame}
\begin{frame}[plain, fragile]
\frametitle{Solution}
\begin{lstlisting}
def kwname(**kw):
return sorted(kw.keys())
\end{lstlisting}
\end{frame}
\begin{frame}[plain, fragile]
\frametitle{Exercise: power function}
\begin{block}{}
Write a function called \lstinline{power} that is given a single integer
and returns a function that takes a single number but returns its power.
For example:
\end{block}
\begin{lstlisting}
In []: pow2 = power(2)
In []: pow2(2)
Out[]: 4
In []: pow2(4)
Out[]: 16
In []: pow3 = power(3)
In []: pow3(2)
Out[]: 8
\end{lstlisting}
Hint: this is a closure.
\end{frame}
\begin{frame}[plain, fragile]
\frametitle{Solution}
\begin{lstlisting}
def power(n):
def g(x):
return x**n
return g
\end{lstlisting}
\end{frame}
\begin{frame}[plain, fragile]
\frametitle{Exercise: debug function}
\begin{block}{}
Write a function called \lstinline{debug} that takes any function as a
single positional argument but returns a function that first prints out
the arguments passed to the function before calling it and returning its
value. For example:
\end{block}
\begin{lstlisting}
In []: debug(max)(1, 2)
(1, 2) {}
Out[]: 2
In []: import math
In []: debug(math.sin)(1.0)
(1.0,) {}
Out[]: 0.8414709848078965
\end{lstlisting}
\end{frame}
\begin{frame}[plain, fragile]
\frametitle{Solution}
\begin{lstlisting}
def debug(f):
def g(*args, **kw):
print(args, kw)
return f(*args, **kw)
return g
\end{lstlisting}
\end{frame}
\end{document}
|
