How To Split A List Into Chunks In Python

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Lists are a useful concept in Python and in many ways are similar to arrays in other programming languages. Python provides a number of list methods which allow you to manipulate the elements within and these are documented in the official data structures documentation.

One thing I needed to do recently was to take a list of data and split it into a number of smaller chunks. I wanted to specify the number of the chunks and the elements of the list to be split appropriately,

In the example below the function “get_chunks” is defined. It accepts two arguments. The first is a list of data and the second is the number of chunks you require.

#!/usr/bin/env python

def main():

  # Create an example list full of numbers
  MyList = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]

  # Print the result of passing the list to the
  # function get_chunks with a value of 4
  print get_chunks(MyList,4)

def get_chunks(MyList, n):

  # Declare some empty lists
  chunk = []
  chunks = []

  # Step through the data n elements
  # at a time
  for x in range(0, len(MyList), n):
    # Extract n elements
    chunk = MyList[x:x+n]
    # Add them to list
    chunks.append(chunk)

  # Return the new list
  return chunks

# Run main function
main()

The function returns a list that contains the chunks as elements. The print statement then prints the resulting list of chunks to screen. You can also populate a new list with the result of “get_chunks” and then handle chunks individually :

  NewList = get_chunks(MyList,4)
  # Print first chunk
  print NewList[0]
  # Print 4th chunk
  print NewList[3]

The following code is a compact version of “get_chunks”. It performs the same process but is much shorter.

def get_chunks2(MyList, n):
  return [MyList[x:x+n] for x in range(0, len(MyList), n)]
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