Python dictionary len() Method

The Python dictionary len() method is used to retrieve the total length of the dictionary. The total length means the number of items which is the key-value pairs in the dictionary.

The len() method returns the number of iterable items in the dictionary. In python, a dictionary is a collection of key-value pairs.

Syntax

Following is the syntax of Python dictionary len() method −

len(dict)

Parameters

  • dict − This is the dictionary, whose length needs to be calculated.

Return Value

This method returns the length of the dictionary.

Example

The following example shows the usage of Python dictionary len() method. First a dictionary 'dict' is created which consists of two key-value pairs. Then the length of the dictionary is retrieved using the len() method.

# Creating a dictionary
dict = {'Name': 'Zara', 'Age': 7};
# printing the result
print ("Length : %d" % len (dict))

When we run above program, it produces following result −

Length : 2

Example

In the code below, a nested dictionary 'dict_1' is created. The length of the nested dictionary is returned using len() method. Here, the method considers only the outer dictionary. Therefore, the value of the key 'Hobby' is considered as a single value.

# nested dictionary
dict_1 = {'Name' :'Rahul', 'RollNo':'43', 'Hobby':{'Outdoor' : 'Cricket', 'Indoor':'Piano'}}
res = len(dict_1)
print("The length of the dictionary is: ", res)

While executing the above code we get the following output −

The length of the dictionary is:  3

Example

In here, we are explicitly adding the total length of the inner dictionary to the outer dictionary.

dict_1 = {'Name' :'Rahul', 'RollNo':'43', 'Hobby':{'Outdoor' : 'Cricket', 'Indoor':'Piano'}}
# calculating the length of the inner dictionary as well
l = len(dict_1) + len(dict_1['Hobby'])
print("The total length of the dictionary is: ", l)

Following is an output of the above code −

The total length of the dictionary is:  5

Example

If we take two or more inner dictionaries, the above example is not the proper way to do it. The correct way is to add the isinstance() method with the len() method. The isinstance() method is used to check if the variable matches the specified data type.

Here we are first storing the dictionary length in the variable 'l'. Then we are iterating through all the values() of the dictionary. This finds out whether it is an instance of dict. Thereafter we get the inner dictionary length and add it to the variable length.

dict_1 = {'Name' :'Rahul', 'RollNo':'43', 'Hobby':{'Outdoor' : 'Cricket', 'Indoor': 'Chesss'}, 'Activity1': {'Relax':'Sleep', 'Workout':'Skipping'}}
# Store the length of outer dict 
l = len(dict_1)
# iterating through the inner dictionary to find its length
for x in dict_1.values():
   # check whether the value is a dict
   if isinstance(x, dict):
      l += len(x)		
print("The total length of the dictionary is", l)

Output of the above code is as follows −

The total length of the dictionary is 8
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