โกSummary: Use given_string.rsplit('sep', 1)
to split the string at the last occurrence. Another approach to solve the problem is to use given_string.rpartition('sep')
Minimal Example:
text = 'Fred fed Ted bread and Ted fed Fred bread' # Method 1 print(text.rsplit('fed', 1)) # OUTPUT: ['Fred fed Ted bread and Ted ', ' Fred bread'] # Method 2 li = list(text.rpartition('fed')) li.remove(li[1]) print(li) # OUTPUT: ['Fred fed Ted bread and Ted ', ' Fred bread']
Problem Formulation
๐Problem: Given a string. How will you split the string at the last occurrence?
Example
Consider that you are given a string with multiple occurrences of the word โscreamโ. You have to split the string at the last occurrence of the word โscreamโ.
# Input: text = 'I scream, you scream, we all scream for ice cream' # Expected Output: ['I scream, you scream, we all ', ' for ice cream']
Letโs dive into the different ways of solving the given problem.
Method 1: Using rsplit
Prerequisite: The rsplit()
method splits a given string based on a given separator and stores the characters/substrings into a list. For example, finxterx123.rsplit('x')
will return the list ['fin', 'ter', '123']
as an output.
rsplit
can take two arguments:sep
โ The separator string on which it is split.maxsplit
โ The number of times the string is split.
๐Read more here: Python String rsplit()
Approach: As we have to split the string only once at the last occurrence, we can use the maxsplit
argument to solve the given problem by setting the maxsplit = 1
. Therefore, the string will split along the specified separator only once from the right end.
Code:
text = 'I scream, you scream, we all scream for ice cream' print(text.rsplit('scream', 1)) # OUTPUT: ['I scream, you scream, we all ', ' for ice cream']
Method 2: Using rpartition
Prereqiuiste: The rpartition()
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. For example: finxterx123'.rpartition('x')
will return the following tuple: ('finxter', 'x', '123')
๐Read more here: Python String rpartition()
Code:
text = 'I scream, you scream, we all scream for ice cream' li = list(text.rpartition('scream')) li.remove(li[1]) print(li) # OUTPUT: ['I scream, you scream, we all ', ' for ice cream']
Explanation: Here, we have used the string โscream
โ as the separator. The rpartition()
method splits the string when it finds the ‘scream’ separator. Now, a problem here is the word โscreamโ is also stored as an item within the list. This is all right if you want to keep the separator. However, in this case we do not need the separator. Hence, we use the remove()
method to eliminate the second element (at index 1) where the separator is stored.
Bonus: rsplit() vs rpartition()
- If you are using the
split()
function, it will split the string at each occurrence of the given delimiter. It returns a list of the words in the string. Similarly we have a method known asrsplit()
. It works the same as thesplit()
function with the only difference being that thersplit()
function splits from the right end of the string. - Whereas, if you use the
partition()
function, it will split the string at the first occurrence of the separator. It returns a tuple containing 3 elements the part before the separator, the separator itself, and the part after the separator. Similarly we have a method known asrpartition()
. It works the same as thepartition()
function with the only difference being that therpartition()
function splits the string at the last occurrence.
Example:
col = "black-red-pink-yellow" print(col.split("-", 1)) print(col.rsplit("-", 1)) print(col.partition("-")) print(col.rpartition("-"))
Output
['black', 'red-pink-yellow'] ['black-red-pink', 'yellow'] ('black', '-', 'red-pink-yellow') ('black-red-pink', '-', 'yellow')
- When you are using the
rsplit()
function, and no separator or delimiter is mentioned, the function will split the string based on the occurrence of whitespaces. Whereas, if a separator or delimiter isnโt mentioned while using therpartition()
function, itโll raise aTypeError
.
col = "black-red pink-yellow blue" print(col.rsplit()) try: print(col.rpartition()) except Exception as e: print(e)
Output
['black-red', 'pink-yellow', 'blue'] str.rpartition() takes exactly one argument (0 given)
Basically, the main difference between the two functions is that the rsplit()
method will split the string at any occurrence of the given argument unless a maxsplit
argument is specified, while the rpartition()
will only split the string at the last occurrence.
Conclusion
I hope the methods to solve the problem used in this tutorial helped you to learn how to split a string at the last occurrence of a specified delimiter. Please subscribe and stay tuned for more interesting tutorials and solutions.
๐Recommended Read: Python | Split String and Get Last Element
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