Python Program that prints elements common at specified index of list elements

Difficulty Level : Basic
Last Updated : 08 Dec, 2020

Given a list of strings, the task is to write a Python program to extract all characters that are same at a specified index of each element of a list.

Input : test_list = [“geeks”, “weak”, “beak”, “peek”]
Output : [‘e’, ‘k’]
Explanation : e and k are at same at an index on all strings.
Input : test_list = [“geeks”, “weak”, “beak”, “peer”]
Output : [‘e’]
Explanation : e is at same at an index on all strings.

Method 1 : Using min(), len() and loop

In this, initially minimum length string is extracted to check indices to iterate to ensure all indices in strings. Then each index is checked for similar character using loop, if found, character is appended to result.

Python3

# initializing Matrix
test_list = ["geeks", "weak", "beak", "peek"]
  
# printing original list
print("The original list is : " + str(test_list))
  
# getting min length string
min_len = min(len(ele) for ele in test_list)
  
res = []
for idx in range(0, min_len):
    flag = True
    for ele in test_list:
  
        # checking for all equal columns
        if ele[idx] != test_list[0][idx]:
            flag = False
            break
  
    if flag:
        res.append(test_list[0][idx])
  
  
# printing result
print("Extracted similar characters : " + str(res))

Output:

The original list is : [‘geeks’, ‘weak’, ‘beak’, ‘peek’]
Extracted similar characters : [‘e’, ‘k’]

Method 2 : Using all(), min(), len() and loop

In this, we perform the task of checking all elements to match using all(), reducing a nested loop, increasing readability.

Python3

# initializing Matrix
test_list = ["geeks", "weak", "beak", "peek"]
  
# printing original list
print("The original list is : " + str(test_list))
  
# getting min length string
min_len = min(len(ele) for ele in test_list)
  
res = []
for idx in range(0, min_len):
  
    # using all() for condition injection
    if all(ele[idx] == test_list[0][idx] for ele in test_list):
        res.append(test_list[0][idx])
  
# printing result
print("Extracted similar characters : " + str(res))

Output:

The original list is : [‘geeks’, ‘weak’, ‘beak’, ‘peek’]
Extracted similar characters : [‘e’, ‘k’]

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