Python Array

1. Datatypes
2. Array in Python

Basically, the array is the collection of similar kinds of data types. In arrays, elements are stored in contiguous memory locations. Python arrays are similar to the python list but the difference is python array can contain elements of similar types only. Similar to the python lists, indexing is possible in python arrays.

Creating a Python Array

Python array can be created by importing array module. In python, to create an array, we need to first declare the code of data type of the elements.

Syntax of the array is given as:

>>>array(data_type_code, value_list)
    

So, during the creation of an array, we've to first write the datatypes and then corresponding value_list. These are enclosed inside the () brackets.

Now, let's create an array.

import array as arr
arr1=arr.array("i",[1,2,4,3,5,6])

print("The Array elements are:\n")
for i in arr1:
    print(1,end=" ")

Output

The Array elements are:
1 2 4 3 5 6
 

Different datatype's specification codes used are listed below:

Code	C Type	Python Type	Min byte
b	signed char	int	1
B	unsigned char	Unicode	2
u	Py_UNICODE	Unicode	2
h	signed short	int	2
H	unsigned short	int	2
i	signed int	int	2
l	signed long	int	4
L	unsigned long	int	4
f	float	float	4
d	double	float	8

Accessing Array Items

To access array items use simply use array indexing. Which is similar to list indexing.

#program that access the array elements.
alpha_Array = arr.array('u', ['a','b','c','d','e'])

print("First Element: ",alpha_Array[0])
print("Last Elements: " ,alpha_Array [-1])
print("Second Last Element: ", alpha_Array[-2])

Output

First Element: a
Last Elements: e
Second Last Element: d
    

Modifying array items-Adding items to the array.

Arrays are almost similar to lists. We can use append(), insert(), extend(), etc functions to perform some modifications.

• The append() method is used to insert the element at the last of the array.
• The insert() method is used to insert the element wherever you want, by giving the required position index in the function.
• The extend() method is used to merge two iterables in the array. We can simply merge another list having the same kind of element to an array.

Example

>>>alpha_array = arr.array('u', ['a','b','c','d','e'])
>>>print(alpha_array)
   array('u', 'abcde')

>>>alpha_array.append('f')
>>>print(alpha_array)
   array('u', 'abcdef')

>>>alpha_array.insert(0,'z')
>>>alpha_array.insert(-1,'y')
   array('u', 'zabcdeyf')

>>>alpha_array.extend(['r','s','t'])
>>>print(alpha_array)
   array('u', 'zabcdeyfrst')

Removing items from an Array

We can simply use del statement, remove(), pop(), etc functions in an array to remove items just similarly we do in a list.

• The del statement: Using the del statement we can remove elements from anywhere, by giving the required index number.
• The pop() method: Using the pop() method we can remove the items from the last.
• The remove() method: The remove() method is used to remove the element from an array by passing the element to be deleted from an array to remove() method.

Example

>>>#Program to delete items from an array with different methods.
>>>alpha_array = arr.array('u', ['Z','a','b','c','d','e','y','f','r','s','t'])
>>>print(alpha_array)
   array('u', 'Zabcdeyfrst')

>>>#The pop() method.
>>>alpha_array.pop()
>>>alpha_array.pop()
>>>print(alpha_array)
   array('u', 'Zabcdeyfr')

>>>#The del statement.
>>>del alpha_array[0]
>>>print(alpha_array)
   array('u', 'acdeyfr')

>>>#The remove() method.
>>>alpha_array.remove('c')
>>alpha_array.remove('d')
>>>print(Alpha_Array)
   array('u', 'abeyfr')

Slicing an Array

We can access the required range of elements by slicing an array. It is done using the slicing operator(':').

Example

>>>import array as arr
>>>int_array = arr.array('i',[23,3,4,2,5,45,6,3,65,43])
>>>print(int_array[:]) #prints all items.
   array('i', [23, 3, 4, 2, 5, 45, 6, 3, 65, 43])

>>>print(int_array[1:]) #prints 1st index to end.
   array('i', [3, 4, 2, 5, 45, 6, 3, 65, 43])

>>>print(int_array[:-1]) #prints second last index to beginning.
   array('i', [23, 3, 4, 2, 5, 45, 6, 3, 65])

>>>print(int_array[2:6]) #prints second index to fifth index.
   array('i', [4, 2, 5, 45])

>>>print(int_array[:-6]) #prints beginning to 5th index.
   array('i', [23, 3, 4, 2])

Changing items with slicing

We can use slicing to insert, replace and delete items from an array. We can modify it for the required range of items using slicing.

Example

>>>import array as arr
>>>arr1 = arr.array('i',[1,2,4,5,6])
>>>print(arr1)
   array('i', [1, 2, 4, 5, 6])

>>>arr1[1:4]= arr.array('i',[8,9,10]) #replaces 1st, 2nd and 3rd indexes.
>>>print(arr1)
   array('i', [1, 8, 9, 10, 6])

>>>del arr1[1:3] #delete 1st & 2nd indexes.
>>>print(arr1)
   array('i', [1, 10, 6])

Seaching items in an array.

We can find the index of a particular element of an array by using the index() method.

Example

import array as arr
arr1 = arr.array('i',[1,2,3,4,5,6])
print(arr1)

print("Index of 3 is: ", arr1.index(3))
print("Index of 4 is: ",arr1.index(4))

print("\nIndex of whole items of an array.")
for i in range(6):
    print(f"Index of {arr1[i]}: ",arr1.index(arr1[i]))

Output

array('i', [1, 2, 3, 4, 5, 6])
Index of 3 is: 2
Index of 4 is: 3

Index of whole items of an array.
Index of 1: 0
Index of 2: 1
Index of 3: 2
Index of 4: 3
Index of 5: 4
Index of 6: 5