Python 2D array

An array is a collection of linear data structures that contain all elements of the same data type in contiguous memory space. It is like a container that holds a certain number of elements that have the same data type. An array’s index starts at 0, and therefore, the programmer can easily obtain the position of each element and perform various operations on the array. In this section, we will learn about 2D (two dimensional) arrays in Python.

Python 2D array

Two-Dimensional Array (2D Array)

A 2D array is an array of arrays that can be represented in matrix form like rows and columns. In this array, the position of data elements is defined with two indices instead of a single index.

Syntax

Array_name = [rows][columns] # declaration of 2D array
Arr-name = [ [m1, m2, m3, … . m_n], [n1, n2, n3, … .. n_n] ]

Where m is the row and n is the column of the table.

Access Two-Dimensional Array

In Python, we can access elements of a two-dimensional array using two indices. The first index refers to the indexing of the list and the second index refers to the position of the elements. If we define only one index with an array name, it returns all the elements of 2-dimensional stored in the array.

Let’s create a simple program to understand 2D (two dimensional) arrays in Python.

2dSimple.py

<br />
Student_dt = [ [72, 85, 87, 90, 69], [80, 87, 65, 89, 85], [96, 91, 70, 78, 97], [90, 93, 91, 90, 94], [57, 89, 82, 69, 60] ]<br />
#print(student_dt[])<br />
print(Student_dt[1]) # print all elements of index 1<br />
print(Student_dt[0]) # print all elements of index 0<br />
print(Student_dt[2]) # print all elements of index 2<br />
print(Student_dt[3][4]) # it defines the 3rd index and 4 position of the data element.<br />

Output:

Python 2D array

In the above example, we passed 1, 0, and 2 as parameters into 2D array that prints the entire row of the defined index. And we have also passed student_dt[3][4] that represents the 3^rd index and 4^th position of a 2-dimensional array of elements to print a particular element.

Traversing the element in 2D (two dimensional)

Program.py

<br />
# write a program to traverse every element of the two-dimensional array in Python.<br />
Student_dt = [ [72, 85, 87, 90, 69], [80, 87, 65, 89, 85], [96, 91, 70, 78, 97], [90, 93, 91, 90, 94], [57, 89, 82, 69, 60] ]<br />
# Use for loop to print the entire elements of the two dimensional array.<br />
for x in Student_dt:  # outer loop<br />
    for i in x:  # inner loop<br />
        print(i, end = ” “) # print the elements<br />
    print()<br />

Output:

Python 2D array

Insert elements in a 2D (Two Dimensional) Array

We can insert elements into a 2 D array using the insert() function that specifies the element’ index number and location to be inserted.

Insert.py

<br />
# Write a program to insert the element into the 2D (two dimensional) array of Python.<br />
from array import * # import all package related to the array.<br />
arr1 = [[1, 2, 3, 4], [8, 9, 10, 12]]  # initialize the array elements.<br />
print(“Before inserting the array elements: “)<br />
print(arr1) # print the arr1 elements.<br />
# Use the insert() function to insert the element that contains two parameters.<br />
arr1.insert(1, [5, 6, 7, 8])  # first parameter defines the index no., and second parameter defines the elements<br />
print(“After inserting the array elements “)<br />
for i in arr1: # Outer loop<br />
    for j in i: # inner loop<br />
        print(j, end = ” “) # print inserted elements.<br />
    print()<br />

Output:

Python 2D array

Update elements in a 2 -D (Two Dimensional) Array

In a 2D array, the existing value of the array can be updated with a new value. In this method, we can change the particular value as well as the entire index of the array. Let’s understand with an example of a 2D array, as shown below.

Create a program to update the existing value of a 2D array in Python.

Update.py

<br />
from array import * # import all package related to the array.<br />
arr1 = [[1, 2, 3, 4], [8, 9, 10, 12]]  # initialize the array elements.<br />
print(“Before inserting the array elements: “)<br />
print(arr1) # print the arr1 elements.</p>
<p>arr1[0] = [2, 2, 3, 3] # update the value of the index 0<br />arr1[1][2] = 99 # define the index [1] and position [2] of the array element to update the value.<br />print(“After inserting the array elements “)<br />for i in arr1: # Outer loop<br />    for j in i: # inner loop<br />        print(j, end = ” “) # print inserted elements.<br />    print()<br />

Output:

Python 2D array

Delete values from a 2D (two Dimensional) array in Python

In a 2- D array, we can remove the particular element or entire index of the array using del() function in Python. Let’s understand an example to delete an element.

Delete.py

<br />
from array import * # import all package related to the array.<br />
arr1 = [[1, 2, 3, 4], [8, 9, 10, 12]]  # initialize the array elements.<br />
print(“Before Deleting the array elements: “)<br />
print(arr1) # print the arr1 elements.</p>
<p>del(arr1[0][2]) # delete the particular element of the array.<br />del(arr1[1]) # delete the index 1 of the 2-D array.</p>
<p>print(“After Deleting the array elements “)<br />for i in arr1: # Outer loop<br />    for j in i: # inner loop<br />        print(j, end = ” “) # print inserted elements.<br />    print()<br />

Output:

Python 2D array

Size of a 2D array

A len() function is used to get the length of a two-dimensional array. In other words, we can say that a len() function determines the total index available in 2-dimensional arrays.

Let’s understand the len() function to get the size of a 2-dimensional array in Python.

Size.py

<br />
array_size = [[1, 3, 2],[2,5,7,9], [2,4,5,6]] # It has 3 index<br />
print(“The size of two dimensional array is : “)<br />
print(len(array_size)) # it returns 3 </p>
<p>array_def = [[1, 3, 2], [2, 4, 5, 6]] # It has 2 index<br />print(“The size of two dimensional array is : “)<br />print(len(array_def)) # it returns 2<br />

Output:

Python 2D array

Write a program to print the sum of the 2-dimensional arrays in Python.

Matrix.py

<br />
def two_d_matrix(m, n): # define the function<br />
    Outp = []  # initially output matrix is empty<br />
    for i in range(m): # iterate to the end of rows<br />
        row = []<br />
        for j in range(n): # j iterate to the end of column<br />
            num = int(input(f “Enter the matrix [{0}][{j}]”))<br />
            row.append(num) # add the user element to the end of the row<br />
        Outp.append(row) # append the row to the output matrix<br />
    return Outp    </p>
<p>def sum(A, B): # define sum() function to add the matrix.<br />    output = [] # initially, it is empty.<br />    print(“Sum of the matrix is :”)<br />    for i in range(len(A)): # no. of rows<br />        row = []<br />        for j in range(len(A[0])): # no. of columns</p>
<p>            row.append(A[i][j] + B[i][j]) # add matrix A and B<br />        output.append(row)<br />    return output    # return the sum of both matrix</p>
<p>m = int(input(“Enter the value of m or Row/n”)) # take the rows<br />n = int(input(“Enter the value of n or columns/n”)) # take the columns</p>
<p>print(“Enter the First matrix “) # print the first matrix<br />A = two_d_matrix(m, n) # call the matrix function<br />print(“display the first (A) matrix”)<br />print(A) # print the matrix</p>
<p>print(“Enter the Second (B) matrix “)<br />B = two_d_matrix(m, n) # call the matrix function<br />print(“display the Second (B) matrix”)<br />print(B) # print the B matrix</p>
<p>s= sum(A, B) # call the sum function<br />print(s) # print the sum of A and B matrix.<br />

Output:

Python 2D array

原创文章，作者：ItWorker，如若转载，请注明出处：https://blog.ytso.com/tech/courses/263576.html

Python 2D array

Python 2D array

Two-Dimensional Array (2D Array)

Access Two-Dimensional Array

Traversing the element in 2D (two dimensional)

Insert elements in a 2D (Two Dimensional) Array

Update elements in a 2 -D (Two Dimensional) Array

Delete values from a 2D (two Dimensional) array in Python

Size of a 2D array

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