Lesson-5: Dictionaries

This blog assumes that you have a Linux machine with Python already installed. 

If you don't, then you can use an AWS cloud based image that has Python. For help, refer to my blog

I am using Python 2.7 for this tutorial.

DICTIONARIES

A dictionary is a list of key:value pairs.

"Name":"Abraham Lincoln"   is a key value pair.

1. Dictionary is defined as follows.

         dict1 = {'Name':'James' , 'Age':27, 'Height':5.9}

2. A value can be retrieved as follows.

         dict1['Name']



Example Program - 7:
********************************************************************
#! /bin/python

dict1 = {'Name': 'James', 'Age':27, 'Height':5.9}

print "\n dict1 = ", dict1  # Check the displayed order of objects

print "\n Name: ", dict1['Name']

dict1['Name'] = 'Andrew'

print "\n Updated dict1 = ", dict1  

print "\n Keys of dict1 = ", dict1.keys()

del dict1['Name']

print "\n Updated dict1 = ", dict1  

print "\n The length of dict1 = ", len(dict1)

dict2 = dict1

# Let us clear dict1

dict1.clear()

print "\n Cleared dict1 = ", dict1  

dict1 = dict2

print "\n Updated dict1 = ", dict1  

print "\n dict2 = ", dict2

********************************************************************

Why do you think both  dict1 and dict2 are empty at the end of the program? You can find the answer in the next lesson.

EXERCISE - 4

Write a program that
1. Defines two dictionaries and prints them
2. Clears dictionary1
3. Assigns dictionary2 to dictionary1 and prints them both
4. Creates two more dictionaries.
4. Tries to concatenation (+) and repetition (*) the latest ones. Check what happens.