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# Python – Escape reserved characters in Strings List

Given List of Strings, escape reserved characters in each String.

Input : test_list = [“Gf-g”, “be)s(t”]
Output : [‘Gf\\-g’, ‘be\\)s\\(t’]
Explanation : All reserved character elements escaped, by adding double \\.

Input : test_list = [“Gf-g”]
Output : [‘Gf\\-g’]
Explanation : All reserved character elements escaped, by adding double \\.

Method #1 : Using join() + list comprehension

In this, we construct the dictionary to map each of reserved character to its escaped version, and then perform the task of replacement in list comprehension and join the result to form Strings.

## Python3

 `# Python3 code to demonstrate working of``# Escape reserved characters in Strings List``# Using list comprehension + join()` `# initializing list``test_list ``=` `[``"Gf-g"``, ``"is*"``, ``"be)s(t"``]` `# printing string``print``(``"The original list : "` `+` `str``(test_list))` `# the reserved string``reserved_str ``=` `"""? & | ! { } [ ] ( ) ^ ~ * : \ " ' + -"""` `# the mapped escaped values``esc_dict ``=` `{ ``chr` `: f``"\\{chr}"` `for` `chr` `in` `reserved_str}` `# performing transformation using join and list comprehension``res ``=` `[ ''.join(esc_dict.get(``chr``, ``chr``) ``for` `chr` `in` `sub) ``for` `sub ``in` `test_list]` `# printing results``print``(``"The resultant escaped String : "` `+` `str``(res))`

Output

```The original list : ['Gf-g', 'is*', 'be)s(t']
The resultant escaped String : ['Gf\\-g', 'is\\*', 'be\\)s\\(t']```

Time Complexity: O(n*n), where n is the length of the input list. This is because we’re using join() + list comprehension which has a time complexity of O(n*n) in the worst case.
Auxiliary Space: O(n), as we’re using additional space res other than the input list itself with the same size of input list.

Method #2 : Using maketrans() + translate() + zip()

In this, the escaping is made by pairing using zip() and maketrans() rather than dictionary for mapping. The translation is done using the result of maketrans().

## Python3

 `# Python3 code to demonstrate working of``# Escape reserved characters in Strings List``# Using maketrans() + translate() + zip()` `# initializing list``test_list ``=` `[``"Gf-g"``, ``"is*"``, ``"be)s(t"``]` `# printing string``print``(``"The original list : "` `+` `str``(test_list))` `# reserved_chars``reserved_chars ``=` `'''?&|!{}[]()^~*:\\"'+-'''` `# the escaping logic``mapper ``=` `[``'\\'` `+` `ele ``for` `ele ``in` `reserved_chars]``result_mapping ``=` `str``.maketrans(``dict``(``zip``(reserved_chars, mapper)))` `# reforming result``res ``=` `[sub.translate(result_mapping) ``for` `sub ``in` `test_list]` `# printing results``print``(``"The resultant escaped String : "` `+` `str``(res))`

Output

```The original list : ['Gf-g', 'is*', 'be)s(t']
The resultant escaped String : ['Gf\\-g', 'is\\*', 'be\\)s\\(t']```

The Time and Space Complexity for all the methods are the same:

Time Complexity: O(n2)

Auxiliary Space: O(n)

My Personal Notes arrow_drop_up