Python – Replace Substrings from String List

Difficulty Level : Medium
Last Updated : 09 Mar, 2020

Sometimes while working with data, we can have a problem in which we need to perform replace substrings with the mapped string to form a shortform of some terms. This kind of problem can have application in many domains involving data. Lets discuss certain ways in which this task can be performed.

Method #1 : Using loop + replace() + enumerate()
The combination of above functions can be used to perform this task. In this, we perform the task of iteration using loop and enumerate() and replacement with a shorter form is done using replace().

# Python3 code to demonstrate 
# Replace Substrings from String List
# using loop + replace() + enumerate()
  
# Initializing list1
test_list1 = ['GeeksforGeeks', 'is', 'Best', 'For', 'Geeks', 'And', 'Computer Science']
test_list2 = [['Geeks', 'Gks'], ['And', '&'], ['Computer', 'Comp']]
  
# printing original lists
print("The original list 1 is : " + str(test_list1))
print("The original list 2 is : " + str(test_list2))
  
# Replace Substrings from String List
# using loop + replace() + enumerate()
sub = dict(test_list2)
for key, val in sub.items():
    for idx, ele in enumerate(test_list1):
        if key in ele:
            test_list1[idx] = ele.replace(key, val)
  
# printing result 
print ("The list after replacement : " + str(test_list1))

Output :

The original list 1 is : ['GeeksforGeeks', 'is', 'Best', 'For', 'Geeks', 'And', 'Computer Science']
The original list 2 is : [['Geeks', 'Gks'], ['And', '&'], ['Computer', 'Comp']]
The list after replacement : ['GksforGks', 'is', 'Best', 'For', 'Gks', '&', 'Comp Science']

Method #2 : Using replace() + list comprehension
This is another way in which this task can be performed. In this, we perform the task of replacing using the replace() and rest of task is performed using list comprehension. It removes list that don’t have replacements.

# Python3 code to demonstrate 
# Replace Substrings from String List
# using replace() + list comprehension
  
# Initializing list1
test_list1 = ['GeeksforGeeks', 'is', 'Best', 'For', 'Geeks', 'And', 'Computer Science']
test_list2 = [['Geeks', 'Gks'], ['And', '&'], ['Computer', 'Comp']]
  
# printing original lists
print("The original list 1 is : " + str(test_list1))
print("The original list 2 is : " + str(test_list2))
  
# Replace Substrings from String List
# using replace() + list comprehension
res = [sub.replace(sub2[0], sub2[1]) for sub in test_list1
      for sub2 in test_list2 if sub2[0] in sub]
  
# printing result 
print ("The list after replacement : " + str(res))

Output :

The original list 1 is : ['GeeksforGeeks', 'is', 'Best', 'For', 'Geeks', 'And', 'Computer Science']
The original list 2 is : [['Geeks', 'Gks'], ['And', '&'], ['Computer', 'Comp']]
The list after replacement : ['GksforGks', 'Gks', '&', 'Comp Science']

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Python – Replace Substrings from String List