From 7082f840a48d17e1aa262b2fd504f8132b1986e4 Mon Sep 17 00:00:00 2001
From: Prabhu Ramachandran
Date: Wed, 8 Feb 2017 22:04:31 +0530
Subject: Fix several mistakes and update practice_ds.
---
basic_python/core_data_structures.tex | 22 +++---
basic_python/practice_control_flow.tex | 7 +-
basic_python/practice_ds.tex | 118 +++++++++++++++++++++++++--------
3 files changed, 109 insertions(+), 38 deletions(-)
(limited to 'basic_python')
diff --git a/basic_python/core_data_structures.tex b/basic_python/core_data_structures.tex
index 9de0954..7bfbb38 100644
--- a/basic_python/core_data_structures.tex
+++ b/basic_python/core_data_structures.tex
@@ -99,9 +99,9 @@ In []: num.index(2)
Out[]: 2
In []: num.pop()
-9
+4
In []: num
-[1, 2, 2, 3, 3, 4, 8]
+[9, 8, 2, 3, 1, 2, 3]
\end{lstlisting}
\end{frame}
@@ -375,22 +375,22 @@ Out[]:
\item Adding a new key-value pair
\end{itemize}
\begin{lstlisting}
- In[]: extensions['c++'] = 'C++ code'
- In[]: extensions
+ In[]: d['c++'] = 'C++ code'
+ In[]: d
\end{lstlisting}
\begin{itemize}
\item Deleting a key-value pair
\end{itemize}
\begin{lstlisting}
- In[]: del extension['java']
- In[]: extensions
+ In[]: del d['java']
+ In[]: d
\end{lstlisting}
\begin{itemize}
\item Assigning to existing key, modifies the value
\end{itemize}
\begin{lstlisting}
- In[]: extensions['cpp'] = 'C++ source code'
- In[]: extensions
+ In[]: d['cpp'] = 'C++ source code'
+ In[]: d
\end{lstlisting}
\end{frame}
@@ -405,7 +405,7 @@ In []: d.get('junk') # No error!
In []: d.update({'bin': 'Binary file',
.....: 'exe': 'executable'})
-In []: d.clear())
+In []: d.clear()
\end{lstlisting}
\end{frame}
@@ -429,6 +429,10 @@ Out[]: False
\begin{frame}[fragile]
\frametitle{Dictionaries: iteration}
\begin{lstlisting}
+In []: for v in d:
+.....: print(v)
+.....:
+
In []: for v in d.values():
.....: print(v)
.....:
diff --git a/basic_python/practice_control_flow.tex b/basic_python/practice_control_flow.tex
index 5ce053f..4fa966b 100644
--- a/basic_python/practice_control_flow.tex
+++ b/basic_python/practice_control_flow.tex
@@ -138,6 +138,7 @@ from __future__ import print_function
\item Use a while loop to generate the numbers from 1 to 10
\item If a number divisible by 3 is found, print ***
\item If a number divisible by 5 is found, print *****
+ \item Otherwise just print the number
\end{enumerate}
\end{frame}
@@ -295,7 +296,7 @@ from __future__ import print_function
\begin{lstlisting}
from numpy import linspace
n = int(input())
- data = linspace(0, 1, n)
+ data = linspace(1, 2, n)
for x in data:
print(x)
\end{lstlisting}
@@ -305,7 +306,7 @@ from __future__ import print_function
\begin{frame}[plain,fragile]
\frametitle{\typ{for} loop over list 2}
\begin{enumerate}
- \item Ask the user for an list of fruits separated by a space
+ \item Ask the user for an list of fruits separated by a comma
\item Print each fruit in a separate line
\end{enumerate}
For example let us say user enters \typ{apple, pear}, print
@@ -365,7 +366,7 @@ from __future__ import print_function
\begin{frame}[fragile,plain]
\frametitle{Solution}
\begin{lstlisting}
- n = input()
+ n = int(input())
for i in range(n):
for j in range(n):
print(i+j, end=' ')
diff --git a/basic_python/practice_ds.tex b/basic_python/practice_ds.tex
index 7931310..9f30319 100644
--- a/basic_python/practice_ds.tex
+++ b/basic_python/practice_ds.tex
@@ -251,6 +251,90 @@ In []: for x, y in data:
\end{lstlisting}
\end{frame}
+\begin{frame}[fragile,plain,fragile]
+ \frametitle{Exercise: simple dictionaries}
+ \begin{enumerate}
+ \item Ask the user for a list of integers separated by spaces
+ \item For each integer, store the string version as the key and the square of
+ the integer value as the value in a dictionary.
+ \item Print the resulting dictionary
+ \end{enumerate}
+For example if the user enters "1 3 5", print:
+\begin{lstlisting}
+{'1': 1, '3': 9, '5': 25}
+\end{lstlisting}
+Hint: simply print the resulting dictionary
+\end{frame}
+
+\begin{frame}[fragile,plain]
+\frametitle{Solution}
+\begin{lstlisting}
+text = input()
+d = {}
+for item in text.split():
+ x = int(item)
+ d[item] = x*x
+print(d)
+\end{lstlisting}
+\end{frame}
+
+
+\begin{frame}[fragile,plain,fragile]
+ \frametitle{Exercise: mapping using dicts}
+ \begin{enumerate}
+ \item Create a mapping from 3 character month name to month number
+ \item Hint: for example \typ{\{'jan': 1, 'dec': 12\}}
+ \item Ask the user for a 3 character month code lower/upper mixed
+ \item Print the month number corresponding to the month the user entered.
+ \end{enumerate}
+For example if the user enters "Jul", print:
+\begin{lstlisting}
+7
+\end{lstlisting}
+\end{frame}
+
+\begin{frame}[fragile,plain]
+\frametitle{Solution}
+\begin{lstlisting}
+months = ('jan feb mar apr may jun jul ' +
+ 'aug sep oct nov dec').split()
+month2mm = {}
+for i in range(1, len(months)+1):
+ month2mm[months[i]] = i
+
+text = input()
+mon = text[:3].lower()
+print(month2mm[mon])
+\end{lstlisting}
+\end{frame}
+
+\begin{frame}[fragile,plain]
+\frametitle{Aside: using \typ{enumerate} example}
+\begin{lstlisting}
+for i, char in enumerate('hello'):
+ print(i, char)
+\end{lstlisting}
+\end{frame}
+
+\begin{frame}[fragile,plain]
+\frametitle{Aside: using \typ{enumerate}}
+\begin{lstlisting}
+months = ('jan feb mar apr may jun jul ' +
+ 'aug sep oct nov dec').split()
+month2mm = {}
+for i, month in enumerate(months):
+ month2mm[month] = i+1
+
+# Is easier/nicer than this:
+
+for i in range(1, len(months)+1):
+ month2mm[months[i]] = i
+\end{lstlisting}
+
+\end{frame}
+
+
+
\begin{frame}[plain,fragile]
\frametitle{Exercise: dictionaries}
\begin{enumerate}
@@ -285,31 +369,6 @@ In []: for x, y in data:
\end{lstlisting}
\end{frame}
-\begin{frame}[plain]
- \frametitle{Problem: Day of the Week}
- \begin{block}{Problem}
- Given a list, \texttt{week}, containing names of the days of the
- week and a string \texttt{s}, check if the string is a day of the
- week. We should be able to check for any of the forms like,
- \emph{sat, Sat, SAT}
- \end{block}
- \begin{itemize}
- \item Ask the user for a string of length 3
- \item Check if the string is a day of the week
- \item Print True or False
- \end{itemize}
-\end{frame}
-
-\begin{frame}[fragile, plain]
- \frametitle{Solution}
- \small
- \begin{lstlisting}
-week = 'mon tue wed thu fri sat sun'.split()
-s = input().lower()
-print(s in week)
-\end{lstlisting}
-\end{frame}
-
\begin{frame}[plain]
{Problem: datestring to date tuple}
@@ -329,7 +388,7 @@ print(s in week)
months = ('jan feb mar apr may jun jul ' +
'aug sep oct nov dec').split()
month2mm = {}
-for i in range(len(months)):
+for i in range(1, len(months)+1):
month2mm[months[i]] = i
date = input()
@@ -342,4 +401,11 @@ mm = month2mm[mon]
print((yyyy, mm, dd))
\end{lstlisting}
\end{frame}
+
+\begin{frame}
+ \centering
+ \Huge
+
+ That's all folks!
+\end{frame}
\end{document}
--
cgit