# Python – All substrings Frequency in String

Given a String, extract all unique substrings with their frequency.

Input : test_str = “ababa”
Output : {‘a’: 3, ‘ab’: 2, ‘aba’: 2, ‘abab’: 1, ‘ababa’: 1, ‘b’: 2, ‘ba’: 2, ‘bab’: 1, ‘baba’: 1}
Explanation : All substrings with their frequency extracted.

Input : test_str = “GFGF”
Output : {‘G’: 2, ‘GF’: 2, ‘GFG’: 1, ‘GFGF’: 1, ‘F’: 2, ‘FG’: 1, ‘FGF’: 1}
Explanation : All substrings with their frequency extracted.

Method #1 : Using loop + list comprehension

The combination of above functionalities can be used to solve this problem. In this, we first extract all the substrings using list comprehension, post that loop is used to increase frequency.

## Python3

 `# Python3 code to demonstrate working of  ` `# All substrings Frequency in String ` `# Using loop + list comprehension ` ` `  `# initializing string ` `test_str ``=` `"abababa"` ` `  `# printing original string ` `print``(``"The original string is : "` `+` `str``(test_str)) ` ` `  `# list comprehension to extract substrings ` `temp ``=` `[test_str[idx: j] ``for` `idx ``in` `range``(``len``(test_str)) ` `       ``for` `j ``in` `range``(idx ``+` `1``, ``len``(test_str) ``+` `1``)] ` ` `  `# loop to extract final result of frequencies ` `res ``=` `{} ` `for` `idx ``in` `temp: ` `     ``if` `idx ``not` `in` `res.keys(): ` `             ``res[idx] ``=` `1` `     ``else``: ` `             ``res[idx] ``+``=` `1` `              `  `# printing result  ` `print``(``"Extracted frequency dictionary : "` `+` `str``(res))  `

Output

```The original string is : abababa
Extracted frequency dictionary : {'a': 4, 'ab': 3, 'aba': 3, 'abab': 2, 'ababa': 2, 'ababab': 1, 'abababa': 1, 'b': 3, 'ba': 3, 'bab': 2, 'baba': 2, 'babab': 1, 'bababa': 1}
```

Method #2 : Using list comprehension

This is yet another way in which this task can be performed. In this, we perform both the tasks, of extracting substring and computing frequency in single nested list comprehension.

## Python3

 `# Python3 code to demonstrate working of  ` `# All substrings Frequency in String ` `# Using list comprehension ` ` `  `# initializing string ` `test_str ``=` `"abababa"` ` `  `# printing original string ` `print``(``"The original string is : "` `+` `str``(test_str)) ` ` `  `# list comprehension to extract substrings and frequency ` `res ``=` `dict``() ` `for` `ele ``in` `[test_str[idx: j] ``for` `idx ``in` `range``(``len``(test_str)) ``for` `j ``in` `range``(idx ``+` `1``, ``len``(test_str) ``+` `1``)]: ` `    ``res[ele] ``=` `1` `if` `ele ``not` `in` `res.keys() ``else` `res[ele] ``+` `1`              `     `  `# printing result  ` `print``(``"Extracted frequency dictionary : "` `+` `str``(res))  `

Output

```The original string is : abababa
Extracted frequency dictionary : {'a': 4, 'ab': 3, 'aba': 3, 'abab': 2, 'ababa': 2, 'ababab': 1, 'abababa': 1, 'b': 3, 'ba': 3, 'bab': 2, 'baba': 2, 'babab': 1, 'bababa': 1}
```

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