Comparison between Lists and Array in Python
Last Updated :
02 Nov, 2023
Python List
Python programming language has four collection data types namely
List, Tuple, Set, and Dictionary
. A list is a mutable and ordered collection i.e., elements of the list can be changed and it maintains the order of insertion of its items. Because of the property of order maintaining, each element of the list has a fixed index and it permits the list to have duplicate elements. In Python, list is very useful as it has the ability to contain non-homogeneous elements. Following are some operations which can be performed on the list:
Python3
IntList = [10, 20, 30]
print("List of numbers: ")
print(IntList)
StrList = ["Geeks", "For", "Geeks"]
print("List of Strings: ")
print(StrList)
Non_homogeneous_list = [10, "Geeks", 20.890,\
"for", 30, "geeks"]
print("List of non-homogeneous elements: ")
print(Non_homogeneous_list)
print("Size of the Non-homogeneous list: ",\
len(Non_homogeneous_list))
NewList = ["Geeks", "for", "Geeks"]
print("Original List: ", NewList)
NewList.append("the")
print("After adding an element the"\
"list becomes: ")
print(NewList)
NewList.insert(3, "is")
print("After adding an element at"\
"index 3 the list becomes: ")
print(NewList)
NewList.extend(["best", "CS", "website"])
print("After adding 3 elements at the"\
"end, the list becomes: ")
print(NewList)
NewList.remove("the")
print("After removing an element"\
"the list becomes: ")
print(NewList)
NewList.pop(3)
print("After removing an element "\
"from index 3 the list becomes: ")
print(NewList)
|
Output
List of numbers:
[10, 20, 30]
List of Strings:
['Geeks', 'For', 'Geeks']
List of non-homogeneous elements:
[10, 'Geeks', 20.89, 'for', 30, 'geeks']
Size of the Non-homogeneous list: 6
Original List: ['Geeks', 'for', 'Geeks']
After adding an element thelist becomes:
['Geeks', 'for', 'Geeks', 'the']
After adding an element atindex 3 the list becomes:
['Geeks', 'for', 'Geeks', 'is', 'the']
After adding 3 elements at theend, the list becomes:
['Geeks', 'for', 'Geeks', 'is', 'the', 'best', 'CS', 'website']
After removing an elementthe list becomes:
['Geeks', 'for', 'Geeks', 'is', 'best', 'CS', 'website']
After removing an element from index 3 the list becomes:
['Geeks', 'for', 'Geeks', 'best', 'CS', 'website']
To get more in-depth knowledge about python list click
here
.
Python Array
Python arrays are also a collection but its items are stored at contiguous memory locations. It can store only homogeneous elements(elements of the same data type). Arrays are very beneficial in performing mathematical operations on the elements. Unlike lists, arrays can not be declared directly. To create an array the
array
module must be imported and the syntax of the declaration is different from that of the list. Following are some operations which can be performed on the array:
Python3
import array as arr
a1 = arr.array('i', [10, 20, 30])
print("Array a1: ", a1)
print ("Elements of the array"\
"a1 is : ", end = " ")
for i in range (len(a1)):
print (a1[i], end =", ")
print()
a2 = arr.array('d', [1.5, 2.4, 3.9])
print ("Elements of the array"\
"a2 is : ", end = " ")
for i in range (len(a2)):
print (a2[i], end =", ")
print()
print ("Original elements of the"\
"array a1 is : ", end = " ")
print(*a1)
a1.append(40)
print ("Elements of the array a1"\
"after adding an element"\
"at last: ", end = " ")
print(*a1)
a1.insert(3, 35)
print ("Elements of the array a1"\
"after adding an element"\
"at index 3: ", end = " ")
print(*a1)
a1.remove(20)
print("Array a1 after removing"\
"element 20: ", end = " ")
print(*a1)
a1.pop(2)
print("Array a1 after removing"\
"element of index 2: ", end = " ")
print(*a1)
|
Output
Array a1: array('i', [10, 20, 30])
Elements of the arraya1 is : 10, 20, 30,
Elements of the arraya2 is : 1.5, 2.4, 3.9,
Original elements of thearray a1 is : 10 20 30
Elements of the array a1after adding an elementat last: 10 20 30 40
Elements of the array a1after adding an elementat index 3: 10 20 30 35 40
Array a1 after removingelement 20: 10 30 35 40
Array a1 after removingelement of index 2: 10 30 40
To get more in-depth knowledge about python array click
here
.
Similarities in Python list and array
Both array and lists are used for storing the data:
The purpose of both the collection is to store the data. While the list is used to store homogeneous as well as non-homogeneous data, an array can store only homogeneous data.
Python3
import array as arr
Homogeneous_List = ["Geeks", "For", "Geeks"]
print("List of Strings: ")
print(Homogeneous_List)
Non_homogeneous_list = [10, "Geeks",\
20.890, "for", 30, "geeks"]
print("List of non-homogeneous elements: ")
print(Non_homogeneous_list)
Homogeneous_array = arr.array('d',\
[1.5, 2.4, 3.9])
print ("Elements of the array is"\
" : ", end = " ")
for i in range (len(Homogeneous_array)):
print (Homogeneous_array[i], end =", ")
|
Output
List of Strings:
['Geeks', 'For', 'Geeks']
List of non-homogeneous elements:
[10, 'Geeks', 20.89, 'for', 30, 'geeks']
Elements of the array is : 1.5, 2.4, 3.9,
List and Array both are mutable:
List, as well as the array, have the ability to modify their elements i.e., they are mutable.
Python3
import array as arr
List1 = ["Geeks", 1, "Geeks"]
print("Original list: ", List1)
List1[1] = "for"
print("\nModified list: ", List1)
Array1 = arr.array('i', \
[10, 20, 30, 37, 50, ])
print ("\nOriginal array: ", end =" ")
for i in range (len(Array1)):
print (Array1[i], end =" ")
Array1[3] = 40
print("\nModified array: ", end ="")
for i in range (len(Array1)):
print (Array1[i], end =" ")
|
Output
Original list: ['Geeks', 1, 'Geeks']
Modified list: ['Geeks', 'for', 'Geeks']
Original array: 10 20 30 37 50
Modified array: 10 20 30 40 50
Elements of both list and array can be accessed by index and iteration:
In order to access the elements of list and array, we have the option of using index number or we can traverse them by iteration.
Python3
import array as arr
List1 = [10, 20, 30, 20, 10, 40]
print("List1 elements: ", List1, "\n")
print("Element at index 0: ", List1[0])
print("Element at index 1: ", List1[1])
print("Element at index 3: ", List1[3])
print("Element at index 4: ", List1[4])
print("Element at last index: ", List1[-1])
print("Element at "\
"3rd last index: ", List1[-3])
print("Accessing through iteration: ", end = " ")
for item in range(len(List1)):
print(List1[item], end =" ")
Array1 = arr.array('i',\
[10, 20, 30, 40, 50, 60])
print("\nArray1: ", Array1)
print("Element of Array1"\
" at index 3: ", Array1[3])
print("Accessing through iteration:"\
" ", end = " ")
for i in range (len(Array1)):
print (Array1[i], end =" ")
|
Output
List1 elements: [10, 20, 30, 20, 10, 40]
Element at index 0: 10
Element at index 1: 20
Element at index 3: 20
Element at index 4: 10
Element at last index: 40
Element at 3rd last index: 20
Accessing through iteration: 10 20 30 20 10 40
Array1: array('i', [10, 20, 30, 40, 50, 60])
Element of Array1 at index 3: 40
Accessing through iteration: 10 20 30 40 50 60
List and array both can be sliced:
Slicing operation is valid for both the list and array to get a range of elements.
Python3
import array as arr
List1 = [10, 20, 30, 20, 10, 40]
print("List elements from "\
"index 1 to 4: ", List1[1:4])
print("List elements from "\
"index 2 to last: ", List1[2:])
Array1 = arr.array('i',
[10, 20, 30, 40, 50, 60])
Sliced_array1 = Array1[1:4]
print("\nSlicing elements of the "\
"array in a\nrange from index 1 to 4: ")
print(Sliced_array1)
Sliced_array2 = Array1[2:]
print("\nSlicing elements of the "\
"array from\n2nd index till the end: ")
print(Sliced_array2)
|
Output
List elements from index 1 to 4: [20, 30, 20]
List elements from index 2 to last: [30, 20, 10, 40]
Slicing elements of the array in a
range from index 1 to 4:
array('i', [20, 30, 40])
Slicing elements of the array from
2nd index till the end:
array('i', [30, 40, 50, 60])
Differences between the Python list and array:
Difference in creation:
Unlike list which is a part of Python syntax, an array can only be created by importing the array module. A list can be created by simply putting a sequence of elements around a square bracket. All the above codes are the proofs of this difference.
Memory consumption between array and lists:
List and array take a different amount of memory even if they store the same amount of elements. Arrays are found to be more efficient in this case as they store data in a very compact manner.
Python3
import array as arr
import sys
List = range(1000)
print("Size of each element of"\
" list in bytes: ", sys.getsizeof(List))
print("Size of the whole list in"\
" bytes: ", sys.getsizeof(List)*len(List))
Array = arr.array('i', [1]*1000)
print("Size of each element of "\
"the array in bytes: ", Array.itemsize)
print("Size of the whole array"\
" in bytes: ", len(Array)*Array.itemsize)
|
Output
Size of each element of list in bytes: 48
Size of the whole list in bytes: 48000
Size of each element of the array in bytes: 4
Size of the whole array in bytes: 4000
Performing mathematical operations:
Mathematical operations like dividing or adding each element of the collection with a certain number can be carried out in arrays but lists do not support these kinds of arithmetic operations. Arrays are optimized for this purpose while to carry out these operations in the list, operations have to be applied to every element separately.
Python3
from numpy import array
List =[1, 2, 3]
Array = array([1, 2, 3])
try:
List = List + 5
except(TypeError):
print("Lists don't support list + int")
try:
Array = Array + 5
print("Modified array: ", Array)
except(TypeError):
print("Arrays don't support list + int")
|
Output
Lists don't support list + int
Modified array: [6 7 8]
Resizing:
Arrays once declared can not be resized. The only way is to copy the elements of the older array into a larger sized array. While the list can be re-sized very efficiently.
Data that can be stored:
List can store both homogeneous as well as non-homogeneous data while arrays support the storage of only homogeneous data.
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