Friday, February 14, 2020

Getting Substring in Python String

In this post we’ll see how to get a substring from a string in Python. Driven by habit most of the developers look for a method in the str class for getting a substring but in Python there is no such method. Getting a substring from a string is done through String slicing in Python.

Format of String slicing is as follows-

Stringname[start_position: end_position: increment_step]

start_position is the index from which the string slicing starts, start_position is included.

end_position is the index at which the string slicing ends, end_position is excluded.

increment_step indicates the step size. For example if step is given as 2 then every alternate character from start_position is accessed.

All of these parameters are optional, if start_position is not specified then the slicing starts from index 0. If end_position is not specified then the slicing ends at string_length – 1 (last index). If increment_step is not specified then increment step is 1 by default.

Getting substring through Python string slicing examples

1. A simple example where substring from index 2..3 is required.

s = "Test String"
print(s[2: 4: 1])

Here slicing is done from index 2 (start_pos) to index 3 (end_pos-1). Step size is 1.

2. Access only the month part from a date in dd/mm/yyyy format. In this case you can use find method to specify the start and end positions for getting a substring.

s = "18/07/2019"
month = s[s.find("/")+1: s.rfind("/") : 1]
print('Month part of the date is-', month)
Month part of the date is- 07

That's all for this topic Getting Substring in Python String. If you have any doubt or any suggestions to make please drop a comment. Thanks!

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Related Topics

  1. Accessing Characters in Python String
  2. Python count() method - Counting Substrings
  3. Comparing Two Strings in Python
  4. Convert String to int in Python
  5. Functions in Python

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