Related Articles

# Python Program to create a List using custom key-value pair of a dictionary

• Last Updated : 02 Feb, 2021

Given a dictionary list, the task here is to write a python program that can convert it to a dictionary with items from values of custom keys.

Input : test_list = [{‘gfg’ : 1, ‘is’ : 4, ‘best’ : 6},

{‘gfg’ : 10, ‘is’ : 3, ‘best’ : 7},

{‘gfg’ : 9, ‘is’ : 4, ‘best’ : 2},

{‘gfg’ : 4, ‘is’ : 1, ‘best’ : 0},

{‘gfg’ : 6, ‘is’ : 3, ‘best’ : 8}], key, value = ‘gfg’, ‘best’

Output : {1: 6, 10: 7, 9: 2, 4: 0, 6: 8}

Explanation : Dictionary with ‘gfg”s keys and ‘best”s values is constructed.

Input : test_list = [{‘gfg’ : 1, ‘is’ : 4, ‘best’ : 6},

{‘gfg’ : 10, ‘is’ : 3, ‘best’ : 7},

{‘gfg’ : 9, ‘is’ : 4, ‘best’ : 2}], key, value = ‘gfg’, ‘best’

Output : {1: 6, 10: 7, 9: 2}

Explanation : Dictionary with ‘gfg”s keys and ‘best”s values is constructed.

Method 1 : Using loop

In this, dictionary list is iterated and values of required custom keys are extracted to declare key value pairs of result dictionary.

Example:

## Python3

 `# initializing list``test_list ``=` `[{``'gfg'``: ``1``, ``'is'``: ``4``, ``'best'``: ``6``},``             ``{``'gfg'``: ``10``, ``'is'``: ``3``, ``'best'``: ``7``},``             ``{``'gfg'``: ``9``, ``'is'``: ``4``, ``'best'``: ``2``},``             ``{``'gfg'``: ``4``, ``'is'``: ``1``, ``'best'``: ``0``},``             ``{``'gfg'``: ``6``, ``'is'``: ``3``, ``'best'``: ``8``}]`` ` `# printing original list``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# initializing key-values``key, value ``=` `'gfg'``, ``'best'`` ` `res ``=` `dict``()``for` `sub ``in` `test_list:`` ` `    ``# constructed values``    ``res[sub[key]] ``=` `sub[value]`` ` `# printing result``print``(``"Dictionary values : "` `+` `str``(res))`

Output:

The original list is : [{‘gfg’: 1, ‘is’: 4, ‘best’: 6}, {‘gfg’: 10, ‘is’: 3, ‘best’: 7}, {‘gfg’: 9, ‘is’: 4, ‘best’: 2}, {‘gfg’: 4, ‘is’: 1, ‘best’: 0}, {‘gfg’: 6, ‘is’: 3, ‘best’: 8}]

Dictionary values : {1: 6, 10: 7, 9: 2, 4: 0, 6: 8}

Method 2 : Using dictionary comprehension

In this, we perform similar task as above method, difference being dictionary comprehension is used to offer one liner alternative to solution.

Example:

## Python3

 `# initializing list``test_list ``=` `[{``'gfg'``: ``1``, ``'is'``: ``4``, ``'best'``: ``6``},``             ``{``'gfg'``: ``10``, ``'is'``: ``3``, ``'best'``: ``7``},``             ``{``'gfg'``: ``9``, ``'is'``: ``4``, ``'best'``: ``2``},``             ``{``'gfg'``: ``4``, ``'is'``: ``1``, ``'best'``: ``0``},``             ``{``'gfg'``: ``6``, ``'is'``: ``3``, ``'best'``: ``8``}]`` ` `# printing original list``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# initializing key-values``key, value ``=` `'gfg'``, ``'best'`` ` `# dictionary comprehension for one liner``res ``=` `{sub[key]: sub[value] ``for` `sub ``in` `test_list}`` ` `# printing result``print``(``"Dictionary values : "` `+` `str``(res))`

Output:

The original list is : [{‘gfg’: 1, ‘is’: 4, ‘best’: 6}, {‘gfg’: 10, ‘is’: 3, ‘best’: 7}, {‘gfg’: 9, ‘is’: 4, ‘best’: 2}, {‘gfg’: 4, ‘is’: 1, ‘best’: 0}, {‘gfg’: 6, ‘is’: 3, ‘best’: 8}]

Dictionary values : {1: 6, 10: 7, 9: 2, 4: 0, 6: 8}

Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.

To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course. And to begin with your Machine Learning Journey, join the Machine Learning – Basic Level Course

My Personal Notes arrow_drop_up