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Python: Find the longest common sub-string from two given strings

Python String: Exercise-69 with Solution

Write a Python program to find the longest common sub-string from two given strings.

Sample Solution:-

Python Code:

from difflib import SequenceMatcher 
  
def longest_Substring(s1,s2): 
  
     seq_match = SequenceMatcher(None,s1,s2) 
  
     match = seq_match.find_longest_match(0, len(s1), 0, len(s2)) 
  
     # return the longest substring 
     if (match.size!=0): 
          return (s1[match.a: match.a + match.size])  
     else: 
          return ('Longest common sub-string not present')  

s1 = 'abcdefgh'
s2 = 'xswerabcdwd'
print("Original Substrings:\n",s1+"\n",s2)
print("\nCommon longest sub_string:")
print(longest_Substring(s1,s2))

Sample Output:

Original Substrings:
 abcdefgh
 xswerabcdwd

Common longest sub_string:
abcd
Original Substrings:
 abcdefgh
 xswerabcdwd

Common longest sub_string:
abcd

Pictorial Presentation:

Python String:  Find the longest common sub-string from two given strings.

Flowchart:

Flowchart: Find the longest common sub-string from two given strings

Python Code Editor:

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Previous: Write a Python program to create two strings from a given string. Create the first string using those character which occurs only once and create the second string which consists of multi-time occurring characters in the said string.
Next: Write a Python program to create a string from two given strings concatenating uncommon characters of the said strings.

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Python: Tips of the Day

Find current directory and file's directory:

To get the full path to the directory a Python file is contained in, write this in that file:

import os 
dir_path = os.path.dirname(os.path.realpath(__file__))

(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)

To get the current working directory use

import os
cwd = os.getcwd()

Documentation references for the modules, constants and functions used above:

  • The os and os.path modules.
  • The __file__ constant
  • os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
  • os.path.dirname(path) (returns "the directory name of pathname path")
  • os.getcwd() (returns "a string representing the current working directory")
  • os.chdir(path) ("change the current working directory to path")

Ref: https://bit.ly/3fy0R6m