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Python language provides us a capability by which we could hold together a set of similar data types, through its feature known as array. In other words, an array allows us to hold multiple values of a same type.

Creating an array in Python

To allow us create an array, Python provides us a special module named array. To create an array, we need to import this array module and call its array function. Let us look at the syntax of this function.

array(typecode, initializer)

While calling the array() function, we need to pass two values - typecode and initializer(a list of values that we are initializing an array with). Let us see one of many values of typecode that we could pass to the array() function.

Type Code	C Type	Python Type	Minimum Size in Bytes
'b'	signed char	int	1
'B'	unsigned char	int	1
'b'	signed char	int	1
'u'	Py_UNICODE	Unicode Character	2
'h'	signed short	int	2
'H'	unsigned char	int	2
'i'	signed int	int	2
'I'	unsigned char	int	2
'l'	signed long	int	4
'L'	unsigned long	int	4
'f'	float	float	4
'd'	double	float	8

• An example of an array


Let us create three arrays by importing the array module. Our first array will contain values of integer type i.e.int, the second other array will contain values of floating-point type i.e. float, while the third array will contain the values of the precision of double type.



# Python  - Example of an array 


import array as arr


# Creating an array of type int
first_array = arr.array('i', [1, 5,3,4,2])
print(first_array)



# Creating an array of type float i.e. with the precision of float 
second_array = arr.array('f', [1.6, 3.8, 4.6])
print(second_array)



# Creating an array of type double i.e. with the precision of double
third_array = arr.array('d', [1.6, 3.8, 4.6])
print(third_array)




Output




array('i', [1, 5, 3, 4, 2])
array('f', [1.600000023841858, 3.799999952316284, 4.599999904632568])
array('d', [1.6, 3.8, 4.6])








Some functions of array module


The array module provides us many important functions using which we could perform many array related operations, such as -
• Creating an array of specific type of elements.
• Traversing through an array.
• Extracting an element from an array.
• Inserting an element into an array.
• Deleting an element from an array.

Let us discuss some important functions of the array module



Function name	Description
insert(i, x)	Inserts an item x at an index i within an array.
pop(i)	Removes an item at an index i from an array and returns it.
remove(x)	Removes the first occurrence of an element x from an array.
reverse()	Reverses the items of an array.
count(x)	Counts the number of occurrences of x in an array.
index(x)	Returns the first occurrence of x in an array.
append(x)	Appends a new item to the end of an array.
extend(iterable)	Appends items from iterable to the end of an array, items in iterable must be of the same type as the array in question.






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• Extracting an element from an array


We could extract any element from an array from its index position. Note: the first element of an array is stored at index zero, second element at index one and so on.



# Python  - Example of an array 


import array as arr


# Creating an array of type int
first_array = arr.array('i', [1, 5, 3, 4, 2])



# Extracting the first element of an array using its index i.e 0
print(first_array[0])


# Extracting the second element of an array using its index i.e 1
print(first_array[1])


# Extracting the third element of an array using its index i.e 2
print(first_array[2])


# Extracting the four element of an array using its index i.e 3
print(first_array[3])


# Extracting the fifth element of an array using its index i.e 4
print(first_array[4])





Output




1
5
3
4
2







• Traversing through an array using for loop


We could traverse through elements of an array using the for loop and print all of its elements. Let us see how it is done.



# Python  - Example of an array 


import array as arr


# Creating an array of type int
first_array = arr.array('i', [1, 5, 3, 4, 2])

# Traversing through the array and printing its each element using a for loop
for x in first_array:
    print(x)




Output

1
5
3
4
2








• Traversing through an array using while loop


We could traverse through an array and extract each of its element using its index position, from within a while loop. For this, we will also have to use the len() function of object class, which takes any iterable type i.e. list, tuple, array etc in its parameters and returns the total number of elements in it.



# Python  - Example of an array 


import array as arr


# Creating an array of type int
first_array = arr.array('i', [1, 5, 3, 4, 2])


# The index of first element of an array
i = 0


# Using while loop to extract each of its element using while loop
# And len() function which takes an iterable type in its parameters i.e. list, tuple, array etc
while(i<len(first_array)):
    print(first_array[i])
    i = i + 1




Output




1
5
3
4
2








• Inserting an element into an array


Unlike programming languages like C, C++, where the once an array is created, some new elements could not be inserted into it, we could insert new elements in an array by using the array module of Python.

To do this, we can call the insert() function of the array module, by passing the index position(where we want to insert the new element), and the element that we want to insert. Let us see an example.



# Python  - Example of an array 

import array as arr



# Creating an array of type int
first_array = arr.array('i', [1, 5, 3, 4, 2])

# Printing the array
print(first_array)


# Calling the insert function of array module to insert integer value 21 at index 1
first_array.insert(1, 21)


# Printing the modified array
print(first_array)



# Calling the insert function to insert integer value 19 at index 4
first_array.insert(4, 19)


# Printing the modified array again
print(first_array)




Output




array('i', [1, 5, 3, 4, 2])
array('i', [1, 21, 5, 3, 4, 2])
array('i', [1, 21, 5, 3, 19, 4, 2])








• Deleting an element from its index in an array


We can delete an element from an array by using the pop() function of the array module, by passing the index position(from where we want to delete the element from the array). Let us see an example.



# Python  - Example of an array 


import array as arr


# Creating an array of type int
first_array = arr.array('i', [1, 5, 3, 4, 2])



# Printing the array
print(first_array)



# Calling the pop function of array module to remove an item at index 1 in the array 
first_array.pop(1)



# Printing the modified array
print(first_array)



# Calling the pop function of array module to remove an item at index 3 in the array 
first_array.pop(3)



# Printing the modified array again
print(first_array)




Output




array('i', [1, 5, 3, 4, 2])
array('i', [1, 3, 4, 2])
array('i', [1, 3, 4])








• Removing the first occurrence of an element in an array


We can remove the first occurrence of an element from an array by using the remove() function of the array module, by passing it the element whose first occurrence has to be deleted from the array. Let us see an example.



# Python  - Example of an array 


import array as arr


# Creating an array of type int
first_array = arr.array('i', [1, 5, 1, 4, 24, 4])



# Printing the array
print(first_array)



# Calling the remove function of array module to remove the first occurrence of an element 1 from array.
first_array.remove(1)



# Printing the modified array
print(first_array)



# Calling the remove function of array module to remove the first occurrence of an element 4 from array.
first_array.remove(4)



# Printing the modified array again
print(first_array)




Output




array('i', [1, 5, 1, 4, 24, 4])
array('i', [5, 1, 4, 24, 4])
array('i', [5, 1, 24, 4])








• Counting the total occurrences of an element in an array


We can find the total occurrence of an element in an array by using the count() function of the array module, by passing it the element whose total occurrences have to be found in an array. Let us see an example.



# Python  - Example of an array 


import array as arr


# Creating an array of type int
first_array = arr.array('i', [1, 5, 1, 4, 24, 4])



# Calling the count() function of array module to find the total occurrence of 1 in it
print('Total occurrences of 1 : ', first_array.count(1))


# Calling the count() function of array module to find the total occurrence of 4 in it
print('Total occurrences of 4 : ', first_array.count(4))



# Calling the count() function of array module to find the total occurrence of 5 in it
print('Total occurrences of 5 : ', first_array.count(5))




Output




Total occurrences of 1 :  2
Total occurrences of 4 :  2
Total occurrences of 5 :  1








• Appending new elements to an array


We can append new elements to the end of an array by using the append() function of the array module, by passing it the new element which will be appended to the end of an array. Let us see an example.



# Python  - Example of an array 

import array as arr


# Creating an array of type int
first_array = arr.array('i', [1, 5, 1, 4, 24, 4])



# Printing the original array.
print(first_array)



# Calling the append() function to append 10 to the end of array
first_array.append(10)


# Printing the modified array.
print(first_array)



# Calling the append() function to append 10 to the end of array
first_array.append(99)



# Printing the modified array.
print(first_array)




Output




array('i', [1, 5, 1, 4, 24, 4])
array('i', [1, 5, 1, 4, 24, 4, 10])
array('i', [1, 5, 1, 4, 24, 4, 10, 99])








• Extending an array


We can extend an array to contain more elements by using the extend() function of array module, which appends items from an iterable type i.e.list, tuple, set, array to the end of an array. Items in iterable must be of the same type as the array we are extending. Let us see an example by extending an array to contain another array.



# Python  - Example of an array 


import array as arr


# Creating an array of type int
first_array = arr.array('i', [1, 5, 1, 4, 24, 4])



# Creating another array of type int
second_array = arr.array('i', [75,10, 100])



# Printing the original first array.
print('First array : ', first_array)



# Printing the original second array.
print('Second array : ",second_array)



# Calling the append() function to append second array to the end of first array
first_array.extend(second_array)


# Printing the extended first array, which also contains second array at its end
print('Extended first array with second array : ', first_array)




Output




First array : array('i', [1, 5, 1, 4, 24, 4])
Second array : array('i', [75, 10, 100])
Extended first array with second array: array('i', [1, 5, 1, 4, 24, 4, 75, 10, 100])






• Extending an array to add an iterable type such as list, set, tuple etc. Let us see an example

# Python  - Example of an array 


import array as arr


# Creating an array of type int
first_array = arr.array('i', [1, 5,  24, 4])



# Creating an iterable list
a_list = [ 5,7,2,2,1]


# Creating a iterable tuple
a_tuple =( 27, 17)



# Creating a iterable set
a_set ={99, 21}



# Printing the priginal first array, list, tuple and set 
print('First array : ',first_array)
print('List : ', a_list)
print('Tuple : ', a_tuple)
print('Set : ', a_set)



# Calling the append() function to append the list to the end of first array
first_array.extend(a_list)



# Printing the modified first array, after extending it to add a list
print('Extended first array with a list : ', first_array)



# Calling the append() function to append the tuple to the end of first array
first_array.extend(a_tuple)



# Printing the modified first array, after extending it to add a tuple
print('Extended first array with a tuple : ', first_array)



# Calling the append() function to append the set to the end of first array
first_array.extend(a_set)



# Printing the modified first array, after extending it to add a set
print('Extended first array with a set : ', first_array)

Output

First array :  array('i', [1, 5, 24, 4])
List :  [5, 7, 2, 2, 1]
Tuple :  (27, 17)
Set :  {99, 21}
Extended first array with a list :  array('i', [1, 5, 24, 4, 5, 7, 2, 2, 1])
Extended first array with a tuple :  array('i', [1, 5, 24, 4, 5, 7, 2, 2, 1, 27, 17])
Extended first array with a set :  array('i', [1, 5, 24, 4, 5, 7, 2, 2, 1, 27, 17, 99, 21])

Array v/s List

While both the array and list are used to contain multiple elements but there is some difference between the two, let us read these differences.

• An array works faster than a list, especially when we have to work with a set of a large number of elements for calculations.
• An array can only contain values of one type, while a list can be used to contain values of different types.
• An array can be one-dimensional or two-dimensional, while a list can only be one-dimensional.

Note :

Besides using the array module to create and work with an array, Python also provides us another module named numpy, which also provides us several important functions to create an array and perform several array related operations and we are going to discuss just that in our next tutorial.

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