# Python | Search Key from Value

• Last Updated : 11 Jun, 2021

The problem of finding a value from a given key is quite common. But we may have a problem in which we wish to get the back key from the input key we feed. Let’s discuss certain ways in which this problem can be solved.
Method #1 : Using Naive Method
In this method, we just run a loop for each of the values and return the corresponding key or keys whose value match. This is the brute force way to perform this particular task.

## Python3

 `# Python3 code to demonstrate working of``# Search Key from Value``# Using naive method` `# initializing dictionary``test_dict ``=` `{``'Gfg'` `: ``1``, ``'for'` `: ``2``, ``'CS'` `: ``3``}` `# printing original dictionary``print``(``"The original dictionary is : "` `+` `str``(test_dict))` `# initializing value``val ``=` `3` `# Using naive method``# Search key from Value``for` `key ``in` `test_dict:``    ``if` `test_dict[key] ``=``=` `val:``        ``res ``=` `key` `# printing result``print``(``"The key corresponding to value : "` `+` `str``(res))`

Output

```The original dictionary is : {'Gfg': 1, 'for': 2, 'CS': 3}
The key corresponding to value : CS
```

Method #2 : Using items() + list comprehension
This problem can be easily solved using the items(), which is used to extract both keys and values at once, hence making the search easy and can be executed using list comprehension making it a one liner.

## Python3

 `# Python3 code to demonstrate working of``# Search Key from Value``# Using items() + list comprehension` `# initializing dictionary``test_dict ``=` `{``'Gfg'` `: ``1``, ``'for'` `: ``2``, ``'CS'` `: ``3``}` `# printing original dictionary``print``(``"The original dictionary is : "` `+` `str``(test_dict))` `# initializing value``val ``=` `3` `# Using items() + list comprehension``# Search key from Value``res ``=` `[key ``for` `key, value ``in` `test_dict.items() ``if` `value ``=``=` `val]` `# printing result``print``(``"The key corresponding to value : "` `+` `str``(res))`

Output

```The original dictionary is : {'Gfg': 1, 'for': 2, 'CS': 3}
The key corresponding to value : ['CS']
```

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