How do you count the number of items in a dictionary python?

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4. Count Number of Keys in Dictionary Python

Created: January-30, 2021 | Updated: February-07, 2021

dict1 = {'a':1,'b':2,'c':3}
print(len(dict1.keys()))

3

dict1 = {'a':1,'b':2,'c':3}
print(len(dict1))

3

dict1 = {'a':1,'b':2,'c':3}

def count_keys(dict):
    count = 0
    for i in enumerate(dict):
        count += 1
    return count

print(count_keys(dict1))

3

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In Python, dictionary is a collection which is unordered, changeable and indexed. Dictionaries are written with curly brackets, and they have keys and values. It is used to hash a particular key. A dictionary has multiple key:value pairs. There can be multiple pairs where value corresponding to a key is a list. To check that the value is a list or not we use the isinstance() method which is inbuilt in Python. isinstance() method takes two parameters:

object - object to be checked
classinfo - class, type, or tuple of classes and types

It return a boolean whether the object is an instance of the given class or not. Let’s discuss different methods to count number of items in a dictionary value that is a list. Method #1 Using in operator 

Python3

def main():

    d = {'A' : [1, 2, 3, 4, 5, 6, 7, 8, 9],

        'B' : 34,

        'C' : 12,

        'D' : [7, 8, 9, 6, 4] }

    count = 0

    for x in d:

        if isinstance(d[x], list):

            count += len(d[x])

    print(count)

if __name__ == '__main__':

    main()

  Method #2: Using list comprehension 

Python3

def main():

    d = {'A' : [1, 2, 3, 4, 5, 6, 7, 8, 9],

        'B' : 34,

        'C' : 12,

        'D' : [7, 8, 9, 6, 4] }

    print(sum([len(d[x]) for x in d if isinstance(d[x], list)]))

if __name__ == '__main__':

    main()

  Method #3: Using dict.items() 

Python3

def main():

    d = { 'A' : [1, 2, 3, 4, 5, 6, 7, 8, 9],

        'B' : 34,

        'C' : 12,

        'D' : [7, 8, 9, 6, 4] }

    count = 0

    for key, value in d.items():

        if isinstance(value, list):

              count += len(value)

    print(count)

if __name__ == '__main__':

    main()

  Method #4: Using enumerate() 

Python3

def main():

    d = {'A' : [1, 2, 3, 4, 5, 6, 7, 8, 9],

        'B' : 34,

        'C' : 12,

        'D' : [7, 8, 9, 6, 4] }

    count = 0

    for x in enumerate(d.items()):

        if isinstance(x[1][1], list):

            count += len(x[1][1])

    print(count)

if __name__ == '__main__':

    main()

Method#5: Using values(),find() and type().

Python3

def main():

    d = {'A' : [1, 2, 3, 4, 5, 6, 7, 8, 9],

        'B' : 34,

        'C' : 12,

        'D' : [7, 8, 9, 6, 4] }

    count = 0

    for x in list(d.values()):

        type1=str(type(x))

        if(type1.find('list')!=-1):

            count+=len(x)

    print(count)

if __name__ == '__main__':

    main()