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Python – Replace dictionary value from other dictionary
• Last Updated : 01 Aug, 2020

Given two dictionaries, update the values from other dictionary if key is present in other dictionary.

Input : test_dict = {“Gfg” : 5, “is” : 8, “Best” : 10, “for” : 8, “Geeks” : 9},
updict = {“Geeks” : 10, “Best” : 17}
Output : {‘Gfg’: 5, ‘is’: 8, ‘Best’: 17, ‘for’: 8, ‘Geeks’: 10}
Explanation : “Geeks” and “Best” values updated to 10 and 17.

Input : test_dict = {“Gfg” : 5, “is” : 8, “Best” : 10, “for” : 8, “Geeks” : 9},
updict = {“Geek” : 10, “Bet” : 17}
Output : {‘Gfg’: 5, ‘is’: 8, ‘Best’: 10, ‘for’: 8, ‘Geeks’: 9}
Explanation : No values matched, hence original dictionary.

Method #1 : Using loop

This is brute way in which this task can be performed. In this, we run a loop for each key in target dictionary and update in case the value is present in other dictionary.

Python3

 `# Python3 code to demonstrate working of  ` `# Replace dictionary value from other dictionary ` `# Using loop ` ` `  `# initializing dictionary ` `test_dict ``=` `{``"Gfg"` `: ``5``, ``"is"` `: ``8``, ``"Best"` `: ``10``, ``"for"` `: ``8``, ``"Geeks"` `: ``9``} ` ` `  `# printing original dictionary ` `print``(``"The original dictionary is : "` `+` `str``(test_dict)) ` ` `  `# initializing updict ` `updict ``=` `{``"Gfg"`  `: ``10``, ``"Best"` `: ``17``} ` ` `  `for` `sub ``in` `test_dict: ` `     `  `    ``# checking if key present in other dictionary ` `    ``if` `sub ``in` `updict: ` `        ``test_dict[sub]  ``=` `updict[sub] ` ` `  `# printing result  ` `print``(``"The updated dictionary: "` `+` `str``(test_dict))  `

Output

The original dictionary is : {‘Gfg’: 5, ‘is’: 8, ‘Best’: 10, ‘for’: 8, ‘Geeks’: 9}
The updated dictionary: {‘Gfg’: 10, ‘is’: 8, ‘Best’: 17, ‘for’: 8, ‘Geeks’: 9}

Method #2 : Using dictionary comprehension

This is one liner approach in which this task can be performed. In this, we iterate for all the dictionary values and update in a one-liner manner in dictionary comprehension.

Python3

 `# Python3 code to demonstrate working of  ` `# Replace dictionary value from other dictionary ` `# Using dictionary comprehension ` ` `  `# initializing dictionary ` `test_dict ``=` `{``"Gfg"` `: ``5``, ``"is"` `: ``8``, ``"Best"` `: ``10``, ``"for"` `: ``8``, ``"Geeks"` `: ``9``} ` ` `  `# printing original dictionary ` `print``(``"The original dictionary is : "` `+` `str``(test_dict)) ` ` `  `# initializing updict ` `updict ``=` `{``"Gfg"`  `: ``10``, ``"Best"` `: ``17``} ` ` `  `res ``=` `{key: updict.get(key, test_dict[key]) ``for` `key ``in` `test_dict} ` ` `  `# printing result  ` `print``(``"The updated dictionary: "` `+` `str``(res))  `

Output

The original dictionary is : {‘Gfg’: 5, ‘is’: 8, ‘Best’: 10, ‘for’: 8, ‘Geeks’: 9}
The updated dictionary: {‘Gfg’: 10, ‘is’: 8, ‘Best’: 17, ‘for’: 8, ‘Geeks’: 9}

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