Python | Split String and Keep Head and Tail

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Summary: You can use the split() method to extract the head and tail elements from a given string.

Minimal Example

dob = '21/08/2023'
head = dob.split('/')[0]
tail = dob.split('/')[-1]
print(f"Head: {head}\nTail: {tail}")

head = dob.partition('/')[0]
tail = dob.rpartition('/')[-1]
print(f"Head: {head}\nTail: {tail}")

# OUTPUTS:
Head: 21
Tail: 2023

In the following articles, we have learned how to split a string and keep the first and last elements separately.

In this article, you will learn how to get the first element and the last element in the same script, i.e., “How to split a string and keep the head and tail elements?”


Problem Formulation

Problem: How to split a string and keep head and tail?

Example: Let’s try to understand the coding challenge with the help of an example.

# Input 
text = "Java_C++_C#_Golang_Python"

# Output
Head: Java
Tail: Python

Note that the first element in the given string is “Java” while the last element is the string “Python”. So, these are the two elements that you need to extract from the given string.

Now that you have a clear picture of what the problem asks you to do, let us dive into the solutions straightaway.

Method 1: Using split

The easiest way to extract the head and tail of the given string is to first split the entire string into a list containing the split substrings. You can then extract the first and the last element from this list using their indices. The index of the first item/element will always be “0” while the last element can be acquired using its negative index, i.e., “-1”.

Code:

text = "Java_C++_C#_Golang_Python"
head = text.split('_')[0]
tail = text.split('_')[-1]
print(f"Head: {head}\nTail: {tail}")

Output:

Head: Java
Tail: Python

Reader’s Digest

split() is a built-in function in Python that splits the string at a given separator and returns a split list of substrings.

Syntax: str.split(sep=None, maxsplit=-1)

  • Return a list of the words in the string, using sep as the delimiter string. If maxsplit is given, at most maxsplit splits are done (thus, the list will have at most maxsplit+1 elements). If maxsplit is not specified or -1, then there is no limit on the number of splits (all possible splits are made).
  • If sep is given, consecutive delimiters are not grouped together and are deemed to delimit empty strings (for example, '1,,2'.split(',') returns ['1', '', '2']).

Method 2: Using partition and rpartition

Prerequisite:

  • The partition() method searches for a separator substring and returns a tuple with three strings:
    • (1) everything before the separator,
    • (2) the separator itself, and
    • (3) everything after it. It then returns a tuple with the same three strings.
  • The rpartition() searches for the last occurrence of the separator substring and returns a tuple with three strings:
    • (1) everything before the separator,
    • (2) the separator itself, and
    • (3) everything after it.

Approach: Thus, you can simply extract the first item from the tuple after the string has been cut by the partition method. Similarly, you can extract the last item from the tuple after the string has been cut by the rpartition method.

Code:

text = "Java_C++_C#_Golang_Python"
head = text.partition('_')[0]
tail = text.rpartition('_')[-1]
print(f"Head: {head}\nTail: {tail}")

Output:

Head: Java
Tail: Python

Conclusion

That was it for this short and important tutorial. I hope it helped you. Please subscribe and stay tuned for more interesting reads and solutions.


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