Python | Convert numeric String to integers in mixed List

Last Updated : 29 Nov, 2019

Sometimes, while working with data, we can have a problem in which we receieve mixed data and need to convert the integer elements in form of strings to integers. This kind of operation might be required in data preprocessing step. Let’s discuss certain ways in which this task can be performed.

Method #1 : Using list comprehension + isdigit()
This is one way in which this task can be performed. In this, we check for each element of string whether it is a number using isdigit and then converted to int if it is one. The iteration is using list comprehension.

# Python3 code to demonstrate working of
# Convert String numbers to integers in mixed List
# using list comprehension + isdigit()
  
# initialize list 
test_list = ["gfg", "1", "is", "6", "best"]
  
# printing original list 
print("The original list : " + str(test_list))
  
# Convert String numbers to integers in mixed List
# using list comprehension + isdigit()
res = [int(ele) if ele.isdigit() else ele for ele in test_list]
  
# printing result
print("List after converting string numbers to integers : " + str(res))

Output :

The original list : ['gfg', '1', 'is', '6', 'best']
List after converting string numbers to integers : ['gfg', 1, 'is', 6, 'best']

Method #2 : Using map() + lambda + isdigit()
This task can also be performed using above functions. In this, we perform the task of iteration using map() and lambda function.

# Python3 code to demonstrate working of
# Convert String numbers to integers in mixed List
# using map() + lambda + isdigit()
  
# initialize list 
test_list = ["gfg", "1", "is", "6", "best"]
  
# printing original list 
print("The original list : " + str(test_list))
  
# Convert String numbers to integers in mixed List
# using map() + lambda + isdigit()
res = list(map(lambda ele : int(ele) if ele.isdigit() 
          else ele, test_list))
  
# printing result
print("List after converting string numbers to integers : " + str(res))

Output :

The original list : ['gfg', '1', 'is', '6', 'best']
List after converting string numbers to integers : ['gfg', 1, 'is', 6, 'best']

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Python | Convert numeric String to integers in mixed List