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Python Dictionary

Creating Python Dictionary

A dictionary is a data structure allowing to have access to a set of data. It is used to have variables with their correspondences. However, the difference between a dictionary and a list is that the bracket delimiter and the indexes of lists are replaced by braces and keys in dictionaries. To create a dictionary, you need two elements which are the keys and the values separated by a colon. Keys and values can be in different type.There are several methods to build a dictionary. The syntaxes are written as follows:

#create dictionary
dict = {}
dict = {'keys':'values', 'keys':'values','keys':'values'}

A key can have values as a list or as a dictionary. In both cases, the creation of the dictionary is done as follows:

#dictionary of dictionairies
dict ={'keys':{'keys': 'values', 'keys':'values', 'keys':'values'}}

#dictionary with value as a list

Verification element in the dictionary

The verification of keys, values in any dictionary is done respectively by these methods. They are written as follows in the lines of code below:

# print Keys
'Keys'in dict 

# Print out value that belong to 'keys'


Delete a key in a dictionary is done in the same way as in a list.

#delete keys

The method of adding a new element to a dictionary is identical to the method of updating it. The code below illustrates this in detail:

#add new element 
Dict['keys'] ='values'

Merge dictionaries

The merging of two dictionaries is done with .update(). The code below tells us this:

# creating two new dictionary
dict_1 ={}
dict_2 ={}

# merge of dictionaries
dict_1. update (Dict_2)

Concrete example

In this practical case, we would create a dictionary and perform the operations seen above. Our dictionary contains information about the price of foodstuffs in Senegal.

#create dictionary
dict_food ={'rice':350, 'oil':150,'sugar':650,'milk':100}

# delete ‘milk’ 

#add new keys
dict_food['corn'] =300
{'rice': 350, 'oil': 150, 'sugar': 650, 'corn': 300}

# another dictionary
dict_sen = {'tomate':1000,'oignon':500,'Pomme de terre':500}

#merging dict_food and dict_sen
{'rice': 350, 'oil': 150, 'sugar': 650, 'corn': 300, 'tomate': 1000, 'oignon': 500, 'potatos': 500}


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