# Python – Maximum occurring Substring from list

Sometimes, while working with Python strings, we can have a problem in which we need to check for maximum occurring subtring from strings list. This can have application in DNA sequencing in Biology and other application. Lets discuss certain way in which this task can be performed.

Method : Using `regex() + groupby() + max()` + lambda
The combination of above functionalities can be used to solve this particular problem. In this, we first extract the sequences using regex function. Then the counter grouping is performed using groupby(). The last step is extracting maximum which is done using max() along with lambda function.

 `# Python3 code to demonstrate working of  ` `# Maximum occurring Substring from list ` `# Using regex() + groupby() + max() + lambda ` `import` `re  ` `import` `itertools ` ` `  `# initializing string ` `test_str ``=` `"gfghsisbjknlmkesbestgfgsdcngfgcsdjnisdjnlbestdjsklgfgcdsbestbnjdsgfgdbhisbhsbestdkgfgb"` `test_list ``=` `[``'gfg'``, ``'is'``, ``'best'``] ` ` `  `# printing original string and list ` `print``(``"The original string is : "` `+` `test_str) ` `print``(``"The original list is : "` `+` `str``(test_list)) ` ` `  `# Maximum occurring Substring from list ` `# Using regex() + groupby() + max() + lambda ` `seqs ``=` `re.findall(``str``.join(``'|'``, test_list), test_str) ` `grps ``=` `[(key, ``len``(``list``(j))) ``for` `key, j ``in` `itertools.groupby(seqs)] ` `res ``=` `max``(grps, key ``=` `lambda` `ele : ele[``1``]) ` `         `  `# printing result  ` `print``(``"Maximum frequency substring : "` `+` `str``(res[``0``]))  `

Output :

```The original string is : gfghsisbjknlmkesbestgfgsdcngfgcsdjnisdjnlbestdjsklgfgcdsbestbnjdsgfgdbhisbhsbestdkgfgb
The original list is : ['gfg', 'is', 'best']
Maximum frequency substring : gfg
```
My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.

Article Tags :

Be the First to upvote.

Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.