Array Module in Python

In Python, Arrays are a type of container that can store elements of the same data type more efficiently. They are provided by the built-in array module and are useful when working with large amounts of numeric data where performance and memory efficiency matter.

Why do we need Arrays?

1. Efficiently store and manage large collections of data of same type.
2. Consume less memory and offer faster performance than lists for numerical operations.
3. Ideal for mathematical and scientific computations where data type consistency is crucial.
4. Support element-wise operations and indexing for quick data manipulation.
5. Useful for working with low-level data structures and when interfacing with C or binary files.

Properties of Arrays

• Each array element is of the same data type and size. For example: For an array of integers with the int data type, each element of the array will occupy 4 bytes.
• Elements of array are stored in contiguous memory locations.

Array Function

The array() function from Python's array module creates an array with elements of a specified data type. It is used to store homogeneous data.

Syntax:

array(typecode, [value1, value2, ...])

Parameter:

• typecode: A single character representing data type (e.g., 'i' for integers, 'f' for floats).
• value list: A list (or iterable) of values matching specified typecode.

Some data types are mentioned in table below:

Operations on Array

Python arrays support various built-in methods to manipulate and manage their elements efficiently. These operations help in adding, removing, searching or modifying data within the array.

Let’s explore each array method one by one with a simple explanation and example:

1. Append() Method

append() method adds a specified value to the end of the array.

Example: This code demonstrates how to create an integer array using array module and then append a new value to it using append() method. It first prints original array, adds number 4 at the end and finally displays updated array.

import array
 
# initializing array with array values and signed integers
arr = array.array('i', [1, 2, 3]) 

# printing original array
print ("The new created array is :",end=" ")
for i in range (0, 3):
    print (arr[i], end=" ")
print("\r")

# using append() to insert new value at end
arr.append(4)

# printing appended array
print("The appended array is : ", end="")
for i in range (len(arr)):
    print (arr[i], end=" ")

The new created array is : 1 2 3 
The appended array is : 1 2 3 4 

2. Insert() Method

insert() method is used to add a value at a specific index in an array. It takes two arguments, position where the element should be inserted and the value to insert.

Example: It demonstrates to use insert() method to add an element at a specific position in an array. It starts by creating an array of signed integers, prints original array, then inserts value 5 at index 2.

import array
 
# initializing array with array values and signed integers
arr = array.array('i', [1, 2, 3]) 

# printing original array
print ("The new created array is : ",end=" ")
for i in range (0, 3):
    print (arr[i], end=" ")

arr.insert(2, 5)

print("\r")

# printing array after insertion
print ("The array after insertion is : ", end="")
for i in range (len(arr)):
    print (arr[i], end=" ")

The new created array is :  1 2 3 
The array after insertion is : 1 2 5 3 

3. Pop() Method

pop() method is used to remove and return element at specified index in an array. If no index is given, it removes the last element by default.

Example: This example shows how to use pop() method. It first initializes an array with integer values, then removes element at index 2 using pop(2) and prints removed element.

import array
 
# initializing array with array values
arr= array.array('i',[1, 2, 3, 1, 5])
 
# printing original array
print ("The new created array is : ",end="")
for i in range (0,5):
    print (arr[i],end=" ")
 
print("\r")
 
# using pop() to remove element at 2nd position
print ("The popped element is : ",end="")
print (arr.pop(2))
 
# printing array after popping
print ("The array after popping is : ",end="")
for i in range (len(arr)):
    print (arr[i],end=" ")

The new created array is : 1 2 3 1 5 
The popped element is : 3
The array after popping is : 1 2 1 5 

4. Remove() Method

remove() method is used to delete the first occurrence of a specific value from the array.

Example: This code shows how to use remove() method to delete first occurrence of a specified value (in this case, 1).

import array
 
arr= array.array('i',[1, 2, 3, 1, 5])
 
# printing original array
print ("The new created array is : ",end="")
for i in range (0,5):
    print (arr[i],end=" ")
 
print("\r")
 
# using remove() to remove 1st occurrence of 1
arr.remove(1)
 
# printing array after removing
print ("The array after removing is : ",end="")
for i in range (len(arr)):
    print (arr[i],end=" ")

The new created array is : 1 2 3 1 5 
The array after removing is : 2 3 1 5 

5. Index() Method

index() method is used to find the position of the first occurrence of a given value in the array.

Example: This code shows how to use index() method. It first creates an array of integers, prints original array and then finds the index of the first occurrence of the value 2 using arr.index(2).

import array
  
# initializing array with array values
arr= array.array('i',[1, 2, 3, 1, 2, 5])
 
# printing original array
print ("The new created array is : ",end="")
for i in range (0,6):
    print (arr[i],end=" ")
 
print("\r")
 
# using index() to print index of 1st occurrence of 2
print ("The index of 1st occurrence of 2 is : ",end="")
print (arr.index(2))

The new created array is : 1 2 3 1 2 5 
The index of 1st occurrence of 2 is : 1

6. Reverse() Method

reverse() method is used to reverse the elements of an array in place.

Example: In this example, the reverse() method is applied to invert the order of elements in-place and finally, reversed array is printed.

import array
  
# initializing array with array values
arr= array.array('i',[1, 2, 3, 1, 2, 5])
 
# printing original array
print ("The new created array is : ",end="")
for i in range (0,6):
    print (arr[i],end=" ")
 
print("\r")
 
#using reverse() to reverse the array
arr.reverse()
 
# printing array after reversing
print ("The array after reversing is : ",end="")
for i in range(len(arr)):
    print (arr[i],end=" ")

The new created array is : 1 2 3 1 2 5 
The array after reversing is : 5 2 1 3 2 1 

Related Article

Array in Python | Set 2 (Important Functions)

Suggested Quiz

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4 Questions

Which of the following is the correct way to create an array in Python using the array module?

• A

  arr = [1, 2, 3]

• B

  arr = array.array('i', [1, 2, 3])

• C

  arr = array('i', [1, 2, 3])

• D

  arr = {1, 2, 3}

Explanation:

array.array method of array module in Python is used to create an array, which is different from lists

How to create an empty array of integers in Python using the array module?

• A

  arr = array.array('i')

• B

  arr = array.array('i', [])

• C

  Both a and b

• D

  None of the above

Explanation:

Both array('i') and array('i', []) can be used to create an empty array of integers.

What is the output of the following array code?

Python

import array  
a = array.array('i', [1, 2, 3])  
a.append(4)  
print(a.tolist())

• A

  [1, 2, 3]

• B

  [1, 2, 3, 4]

• C

  [4, 3, 2, 1]

• D

  Error

Explanation:

append() adds 4 to the end of the array.

What does arr.remove(1) do in an array?

• A

  Removes all 1s

• B

  Removes last element

• C

  Removes the first occurrence of 1

• D

  Throws an error

Explanation:

The remove() method deletes the first match found.

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