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# Python – Dictionary value lists lengths product

• Last Updated : 01 Aug, 2020

Given a dictionary with values as lists, compute lengths of each list, and find product of all lengths.

Input : test_dict = {‘Gfg’ : [6, 5, 9, 3], ‘is’ : [1, 3, 4], ‘best’ :[9, 16]}
Output : 24
Explanation : 4 * 3 * 2 = 24. Length of lists are 4, 3, and 2.

Input : test_dict = {‘Gfg’ : [6, 5, 3], ‘is’ : [1, 3, 4], ‘best’ :[9, 16]}
Output : 18
Explanation : 3 * 3 * 2 = 18. Length of lists are 3, 3, and 2.

Method #1 : Using loop + len()

This is one of the ways in which this task can be performed. In this, we iterate for all the values and use len() to get length of all value lists, post which we perform multiplication of whole data.

## Python3

 `# Python3 code to demonstrate working of ``# Dictionary value lists lengths product``# Using loop + len()`` ` `# initializing dictionary``test_dict ``=` `{``'Gfg'` `: [``6``, ``5``, ``9``, ``3``, ``10``],``             ``'is'` `: [``1``, ``3``, ``4``], ``             ``'best'` `:[``9``, ``16``]}`` ` `# printing original dictionary``print``(``"The original dictionary is : "` `+` `str``(test_dict))`` ` `# using loop to iterate through all keys ``res ``=` `1``for` `key ``in` `test_dict:``     ` `    ``# len() used to get length of each value list``    ``res ``=` `res ``*` `len``(test_dict[key])    `` ` `# printing result ``print``(``"The computed product : "` `+` `str``(res)) `
Output
```The original dictionary is : {'Gfg': [6, 5, 9, 3, 10], 'is': [1, 3, 4], 'best': [9, 16]}
The computed product : 30
```

Method #2 : Using map() + lambda + reduce()

The combination of above functions provide one-liner approach to solve this problem. In this, we use map() to get lengths of all lists extending len() to each list, lambda is used to get product and reduce to combine.

## Python3

 `# Python3 code to demonstrate working of ``# Dictionary value lists lengths product``# Using map() + lambda + reduce() ``from` `functools ``import` `reduce`` ` `# initializing dictionary``test_dict ``=` `{``'Gfg'` `: [``6``, ``5``, ``9``, ``3``, ``10``],``             ``'is'` `: [``1``, ``3``, ``4``], ``             ``'best'` `:[``9``, ``16``]}`` ` `# printing original dictionary``print``(``"The original dictionary is : "` `+` `str``(test_dict))`` ` `# values() used to get all lists of keys``res ``=` `reduce``(``lambda` `sub1, sub2: sub1 ``*` `sub2, ``map``(``len``, test_dict.values()))`` ` `# printing result ``print``(``"The computed product : "` `+` `str``(res)) `
Output
```The original dictionary is : {'Gfg': [6, 5, 9, 3, 10], 'is': [1, 3, 4], 'best': [9, 16]}
The computed product : 30
```

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