Split a String by Custom Lengths in Python

In this article, we will learn how to split a string by custom lengths in python.

Methods Used

The following are the various methods to accomplish this task ?

• Using for loop and slicing

• Using List Comprehension, join() and next() functions

Example

Assume we have taken an input string and custom lengths list. We will now split an input string by input custom lengths using the above methods.

Input

inputString = 'hitutorialspoint'
customLengths = [4, 1, 6, 5]

Output

['hitu', 't', 'orials', 'point']

In the above example, firstly the input list is split based on the given custom lengths ?

4 characters - 'hitu'

1 character - ?r'

6 characters - ?orials'

5 'characters - ?point

Method 1: Using for loop and slicing

Algorithm (Steps)

Following are the Algorithms/steps to be followed to perform the desired task -.

• Create a variable to store an input string.

• Print the input string.

• Create a variable to store an input custom lengths list.

• Create an empty list for storing the resultant list.

• Initialize the start index as 0.

• Use the for loop to traverse through each element of the custom lengths list.

• Use the append() function(adds the element to the list at the end) to append the result that is sliced between the given indices.

• Increment the value of the start index with the custom length list element.

• Print the resultant list after splitting the input list by given custom lengths.

Example

The following program returns a list after splitting the input list by given custom lengths using for loop and slicing -

# input string
inputString = 'hitutorialspoint'

# printing input string
print("Input string: ", inputString)

# input custom lengths list
customLengths = [4, 1, 6, 5]

# empty list for storing a resultant list
outputList = []

# initializing start index as 0
startIndex = 0

# travsering through each element of the custom lengths list
for l in customLengths:

   # appending the custom length string sliced from the
   
   # starting index to the custom length element
   outputList.append(inputString[startIndex: startIndex + l])
   
   # Increment the start Index value with the custom length element
   startIndex += l

# printing the resultant output list
print("Resultant list after splitting by custom lengths:\n", outputList)

Output

On executing, the above program will generate the following output -

Input string: hitutorialspoint
Resultant list after splitting by custom lengths:
['hitu', 't', 'orials', 'point']

Method 2: Using List Comprehension, join() and next() functions

List Comprehension

When you wish to build a new list based on the values of an existing list, list comprehension provides a shorter/concise syntax.

next() function

Returns the next item in an iterator like a list, string tuple, etc. If the iterable reaches its end, you can add a default return value to return.

Syntax

next(iterable, default)

join() function ? join() is a string function in Python that is used to join elements of a sequence that are separated by a string separator. This function connects sequence elements to convert to a string.

iter() function

Returns an iterator for the given object. It creates an object that iterates one element at a time.

Syntax

Below is the syntax of the function.

iter(object, sentinel)

Parameters

• object ? The object whose iterator(list, tuples, sets etc) to be created is specified by this parameter

• sentinel ? It is a unique value that indicates the end of a sequence.

Algorithm (Steps)

Following are the Algorithm/steps to be followed to perform the desired task -

• Use the iter() function to return an iterator for the input string(iterating through string)

• Traverse through each element of customLengths list and Join the next l(iterator value) characters of the string using the next() and join() function.

• Print the resultant list after splitting the input list by given custom lengths.

Example

The following program returns a list after splitting the input list by given custom lengths using list comprehension, join(), and next() functions -

# input string
inputString = 'hitutorialspoint'

# printing input string
print("Input string: ", inputString)

# input custom lengths list
customLengths = [4, 1, 6, 5]

# Getting the string as an iter object to iterate through it
stringitr = iter(inputString)

# traversing through each element of customLengths list and

# Joining the next l characters of the string
outputList = ["".join(next(stringitr) for i in range(l)) for l in customLengths]

# printing the resultant output list
print("Resultant list after splitting by custom lengths:\n", outputList)

Output

On executing, the above program will generate the following output -

Input string: hitutorialspoint
Resultant list after splitting by custom lengths:
['hitu', 't', 'orials', 'point']

Conclusion

In this article, we learned how to split the given string into different lengths using 2 different methods. Additionally, we learned how to use the iter() method to iterate through the string and the next() function to get the string up to n characters.