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String Slicing

String Slicing

Get familiar with string slicing in Python, including basic slicing, slicing with a step, reverse slicing, partial slicing, and slicing by character.

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The technique of extracting a portion of a string by utilizing its indices is called slicing. Several real-world applications use slicing. For example, slicing can be used to extract the required information from messages sent over a communication because they conform to a specific format. Several data processing and cleaning tasks like web scraping, tokenization, and feature extraction also benefit from slicing.

Slicing in Python

For a given string, we can use the following template to slice it and retrieve a substring:

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string[start:end]

  • The start index indicates where we want the substring to begin.

  • The end index specifies where we want the substring to terminate. The character at the end index will not be included in the substring obtained through this method.

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Here’s an example illustrating the use of the slicing:

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my_string = "This is MY string!"
print(my_string[0:4]) 
print(my_string[1:7])
print(my_string[8:len(my_string)])

Explanation

Here’s the code explanation:

  • Line 2: This expression extracts a substring from my_string starting from the index 0 (inclusive) up to, but not including, the index 4. So it prints This, which are the characters at indices 0, 1, 2, and 3.

  • Line 3: This expression extracts a substring from my_string starting from the index 1 (inclusive) up to, but not including, the index 7. So it prints his is, which are the characters at indices 1, 2, 3, 4, 5, and 6.

  • Line 4: This expression extracts a substring from my_string starting from the index 8 (inclusive) until the end of the string. The len(my_string) function returns the length of the string, ensuring that it captures all characters until the end. So it prints MY ...