This post was last Updated on June 7, 2022 by Himanshu Tyagi to reflect the accuracy and up-to-date information on the page.
This article will discuss how to create an empty array in Python. We will also see different methods available to perform operations on the array.
An array is a data structure that will store the same data type elements. In Python, we can create an array using the NumPy module.
Numpy stands for numeric Python used to process the arrays. We can create an array in numpy and reverse the array using some inbuilt functions available in numpy.
Syntax:
import numpy
Creation:
We can create an array through the numpy module.
Syntax:
numpy.array([elements])
We can also consider a list array in Python.
The list is a data structure in Python used to store elements with multiple data types. We can create a list by using [].
Also Read: How to Create Python Empty Set
Method 1: Creating an empty NumPy array
#importing numpy module import numpy #create an empty numpy array my_array=numpy.array([]) #display print(my_array)
Output:
[]
Method 2: Creating an empty list array
#create an empty list my_array=[] #display print(my_array)
Output:
[]
Also Read: How To Create An Empty Dictionary in Python
Method 3: Creating an empty list array with 0’s
In this example, we create a list with 10 0’s and display the list and number of elements in the list using the len() function.
#create an empty list my_array=[0]*10 #display print(my_array) #get the length print(len(my_array))
Output:
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0] 10
Method 4: Creating an empty list array with None values
In this example, we create a list with 10 None values and display the list and number of elements in the list using the len() function.
#create an empty list my_array=[None]*10 #display print(my_array) #get the length print(len(my_array))
Output:
[None, None, None, None, None, None, None, None, None, None] 10
Also Read: What Is Python Used For? Applications of Python
Python List Methods
1. append()
This method is used to add an element to a list.
Syntax:
my_array.append(element)
Where my_array is an input list and element is the value to be added.
Example:
We will create an array with 10 elements and add a string value to the list in this example.
#create an list
my_array=[1,23,45,3,34,6,7,8,9,32]
#display
print(my_array)
#add the string element - "hello"
my_array.append("hello")
#display the list
print(my_array)
Output:
[1, 23, 45, 3, 34, 6, 7, 8, 9, 32] [1, 23, 45, 3, 34, 6, 7, 8, 9, 32, 'hello']
Also Read: How to Convert Binary to Decimal in Python [5 Methods]
2. clear()
This method is used to remove all the elements from the list.
Syntax:
my_array.clear()
where my_array is an input list.
Example:
This example will create an array with 10 elements and remove all elements.
#create an list my_array=[1,23,45,3,34,6,7,8,9,32] #display print(my_array) #clear the array my_array.clear() #display the list print(my_array)
Output:
[1, 23, 45, 3, 34, 6, 7, 8, 9, 32] []
Also Read: How to Reverse an Array In Python [Flip Array]
3. copy()
This method is used to copy the first list to the new list
Syntax:
my_array.copy()
where my_array is an input list.
Example:
We will create an array with 10 elements and copy all elements to the first list in this example.
#create an list my_array=[1,23,45,3,34,6,7,8,9,32] #display print(my_array) #copy the array my_array1=my_array.copy() #display the list print(my_array1)
Output:
[1, 23, 45, 3, 34, 6, 7, 8, 9, 32] [1, 23, 45, 3, 34, 6, 7, 8, 9, 32]
Also Read: Python For Loop Index With Examples
4. count()
This method is used to count the particular element in a list
Syntax:
my_array.count('element')
where my_array is an input list and element is to be counted.
Example:
In this example, we will create an array with 10 elements and count particular elements in the list.
#create an list my_array=[1,1,45,45,34,6,7,7,9,45] #display print(my_array) #get the count of 45 print(my_array.count(45)) #get the count of 1 print(my_array.count(1)) #get the count of 7 print(my_array.count(7))
Output:
[1, 1, 45, 45, 34, 6, 7, 7, 9, 45] 3 2 2
Also Read: How to Handle String Index Out of Range Error In Python
5. extend()
This method is used to add a list to a list.
Syntax:
my_array.append(list)
Where my_array is an input list, and the list is the other list to be appended to the first list.
Example:
In this example, we will create an array with 10 elements and add an exact list to the list.
#create an list my_array=[1,23,45,3,34,6,7,8,9,32] #display print(my_array) #append the list my_array.extend(my_array) #display the list print(my_array)
Output:
[1, 23, 45, 3, 34, 6, 7, 8, 9, 32] [1, 23, 45, 3, 34, 6, 7, 8, 9, 32, 1, 23, 45, 3, 34, 6, 7, 8, 9, 32]
Also Read: How to Convert Python Tuples to Lists
6. index()
This method returns the index of a particular element in a list. Indexing starts with 0.
Syntax:
my_array.index('element')
where my_array is an input list.
Example:
In this example, we will create an array with 10 elements and get the indices of particular elements in the list.
#create an list my_array=[1,1,45,45,34,6,7,7,9,45] #display print(my_array) #get the index of 1 print(my_array.index(1)) #get the index of 45 print(my_array.index(45)) #get the index of 9 print(my_array.index(9))
Output:
[1, 1, 45, 45, 34, 6, 7, 7, 9, 45] 0 2 8
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7. insert()
This method is used to insert the elements at the given index position. It will take two parameters.
The first parameter is the index position where an element is to be inserted, and the second parameter takes the element.
Syntax:
my_array.insert(index,'element')
where my_array is an input list.
Example:
This example will create an array with 10 elements and insert the elements at particular positions.
#create an list my_array=[1,1,45,45,34,6,7,7,9,45] #display print(my_array) #insert the string - "hello" at third position my_array.insert(2,"hello") #insert the string - "welcome" at last position my_array.insert(10,"hello") #insert the string - "bye" at fifth position my_array.insert(4,"bye") #display list print(my_array)
Output:
[1, 1, 45, 45, 34, 6, 7, 7, 9, 45] [1, 1, 'hello', 45, 'bye', 45, 34, 6, 7, 7, 9, 'hello', 45]
Also Read: Python Matrix Using Numpy [With Examples]
8. pop()
This method removes an element from the list based on the given index. By default, it will remove the last item. Indexing starts with 0.
Syntax:
my_array.pop(index)
where my_array is an input list.
Example 1:
This example will create an array with 10 elements and apply pop() on the array.
#create an list my_array=[1,2,3,4,5,6,7,8,9,34] #display print(my_array) #removes the last item my_array.pop() #display list print(my_array)
Output:
[1, 2, 3, 4, 5, 6, 7, 8, 9, 34] [1, 2, 3, 4, 5, 6, 7, 8, 9]
Example 2:
In this example, we will create an array with 10 elements and apply pop() to remove elements present in the indices – 1,2, and 7.
#create an list my_array=[1,2,3,4,5,6,7,8,9,34] #display print(my_array) #removes the element present at index - 1 my_array.pop(1) #removes the element present at index - 2 my_array.pop(2) #removes the element present at index - 7 my_array.pop(7) #display list print(my_array)
Output:
[1, 2, 3, 4, 5, 6, 7, 8, 9, 34] [1, 3, 5, 6, 7, 8, 9]
Also Read: How To Sort a List of Tuples in Python
9. remove()
This method is used to remove an element from the list.
Syntax:
my_array.pop(element)
where my_array is an input list.
Example:
In this example, we will create an array with 10 elements and apply to remove() on the array to remove particular elements.
#create an list my_array=[1,2,3,4,5,6,7,8,9,34] #display print(my_array) #removes the element 1 my_array.remove(1) #removes the element 34 my_array.remove(34) #removes the element 5 my_array.remove(5) #display list print(my_array)
Output:
[1, 2, 3, 4, 5, 6, 7, 8, 9, 34] [2, 3, 4, 6, 7, 8, 9]
Also Read: How To Display A Calendar In Python
10. reverse()
This method is used to reverse the list of elements.
Syntax:
my_array.reverse()
where my_array is an input list.
Example:
We will create an array with 10 elements and reverse the list in this example.
#create an list my_array=[1,2,3,4,5,6,7,8,9,34] #display print(my_array) #reverse the array my_array.reverse() #display print(my_array)
Output:
[1, 2, 3, 4, 5, 6, 7, 8, 9, 34] [34, 9, 8, 7, 6, 5, 4, 3, 2, 1]
Also Read: Arithmetic Operators in Python [With Examples]
11. sort()
This method is used to sort the list of elements.
Syntax:
my_array.sort(reverse)
Where my_array is an input list, and the reverse is a parameter that takes boolean values. It will sort the list in ascending order if it is set to False and sorts the list in descending order if it is True.
Example 1:
We will create an array with 10 elements in this example and sort the list in decreasing order.
#create an list my_array=[1,42,3,4,23,6,7,8,9,34] #display print(my_array) #sort the array in descending order my_array.sort(reverse=True) #display print(my_array)
Output:
[1, 42, 3, 4, 23, 6, 7, 8, 9, 34] [42, 34, 23, 9, 8, 7, 6, 4, 3, 1]
Example 2:
We will create an array with 10 elements in this example and sort the list in ascending order.
#create an list my_array=[1,42,3,4,23,6,7,8,9,34] #display print(my_array) #sort the array in increasing order my_array.sort(reverse=False) #display print(my_array)
Output:
[1, 42, 3, 4, 23, 6, 7, 8, 9, 34] [1, 3, 4, 6, 7, 8, 9, 23, 34, 42]
Also Read: How to Convert Binary to Decimal in Python [5 Methods]
12. len()
This function is used to get the total number of elements present in the list.
Syntax:
len(my_array)
where my_array is an input list
Example:
In this example, we will get the length of the list.
#create an list my_array=[1,42,3,4,23,6,7,8,9,34] #display print(my_array) #get the length print(len(my_array))
Output:
[1, 42, 3, 4, 23, 6, 7, 8, 9, 34] 10
Also Read: Python Program To Display Fibonacci Series Up To N Terms
Summary
From this tutorial, we learned about creating empty arrays in Python, and we discussed how to add, delete and sort the elements in a list/array in Python.
To get the index from the list, we used the index() method, and also, to count the total number of occurrences of a particular element in a list, we used the count() method.
Finally, we closed this tutorial by seeing how to get the total number of elements present in the list.
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