Python - Sort Arrays

Python's array module defines the array class. An object of array class is similar to the array as present in Java or C/C++. Unlike the built-in Python sequences, array is a homogenous collection of either strings, or integers, or float objects.

The array class doesn't have any function/method to give a sorted arrangement of its elements. However, we can achieve it with one of the following approaches −

  • Using a sorting algorithm

  • Using the sort() method from List

  • Using the built-in sorted() function

Let's discuss each of these methods in detail.

Sort Arrays Using a Sorting Algorithm

We shall implement the classical bubble sort algorithm to obtain the sorted array. To do it, we use two nested loops and swap the elements for rearranging in sorted order.

Example

Save the following code using a Python code editor −

import array as arr
a = arr.array('i', [10,5,15,4,6,20,9])
for i in range(0, len(a)):
   for j in range(i+1, len(a)):
      if(a[i] > a[j]):
         temp = a[i];
         a[i] = a[j];
         a[j] = temp;
print (a)

It will produce the following output −

array('i', [4, 5, 6, 9, 10, 15, 20])

Sort Arrays Using sort() Method of List

Even though array doesn't have a sort() method, Python's built-in List class does have a sort method. We shall use it in the next example.

First, declare an array and obtain a list object from it, using tolist() method −

Example

a = arr.array('i', [10,5,15,4,6,20,9])
b=a.tolist()

We can easily obtain the sorted list as follows −

b.sort()

All we need to do is to convert this list back to an array object −

a.fromlist(b)

Here is the complete code −

from array import array as arr
a = arr.array('i', [10,5,15,4,6,20,9])
b=a.tolist()
b.sort()
a = arr.array('i')
a.fromlist(b)
print (a)

It will produce the following output −

array('i', [4, 5, 6, 9, 10, 15, 20])

Sort Arrays Using sorted() Method

The third technique to sort an array is with the sorted() function, which is a built-in function.

The syntax of sorted() function is as follows −

sorted(iterable, reverse=False)

The function returns a new list containing all items from the iterable in ascending order. Set reverse parameter to True to get a descending order of items.

The sorted() function can be used along with any iterable. Python array is an iterable as it is an indexed collection. Hence, an array can be used as a parameter to sorted() function.

Example

from array import array as arr
a = arr.array('i', [4, 5, 6, 9, 10, 15, 20])
sorted(a)
print (a)

It will produce the following output −

array('i', [4, 5, 6, 9, 10, 15, 20])
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