Python Dictionary Comprehension

What is Comprehension

?We create a sequence from a given sequence is called comprehension

?Sequence means list, tuple, string and range

?Some sequence allow comprehension but some not

?As tuple did not allow comprehension as we do in list

?We can create dictionary from another dictionary or sequence

Why need of Comprehension

?Filtering & Searching

?Fastest way

?One line of code

?Simplicity

Python Dictionary Comprehension

Using dictionary comprehension, we can create another dictionary from existing dictionary or existing sequence on the basis of some conditions.

Understand

• Key
• Value
• Item

Example: dict = {'a': 4, 'b': 1, 'c': 6, 'd': 2, 'e': 3}

Syntax:

dict_var = {key:value for (key,value) in dictonary.items()/sequence}

Example

dict = {'a': 4, 'b': 1, 'c': 6, 'd': 2, 'e': 3}

new_dict = {k:v*3 for (k,v) in dict.items()}

print(new_dict)

Python Dictionary Comprehension Syntax

newDict = [key:value for (key, value) in dictionary.items/sequence]

newDict = [key:value for (key, value) in dictionary.items/sequence if statement]

newDict = [key:value if statement else statement for (key, value) in dictionary.items/sequence]

newDict = [key:value for (key, value) in dictionary.items/sequence nested if statement]

Python Dictionary Comprehension Examples

Examples 1:

dict = {'a': 4, 'b': 1, 'c': 6, 'd': 2, 'e': 3}

new_dict = {k:v*5 for (k,v) in dict.items()}

Example? 2:

new_dict = {k:v for (k,v) in dict.items() if ‘a’ in k}

Example? 3:

dict = {'a': 3 'b': 12, 'c': 6, 'd': 10, 'e': 15, 'f': 9}

new_dict = {k: (‘even' if v % 2 == 0 else ‘odd')? for (k,v) in dict.items()}

Example? 4:

dict = {'a': 20 'b': 12, 'c': 6, 'd': 10, 'e': 15, 'f': 9}

new_dict = {k:v? for (k,v) in dict.items() if v%2 == 0 if v%3 ==0}