Array is a data structure used to store elements. An array can only store similar types of elements. A Two Dimensional is defined as an Array inside the Array. The index of the array starts with 0 and ends with a size of array minus 1. We can create ‘n’ number of arrays in an array.
How to Create Array in Python?
We can create a two-dimensional array(list) with rows and columns.
Syntax:
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<strong>[[</strong>r1,r2,r3,..,rn<strong>],[</strong>c1,c2,c3,.......,cn<strong>]]</strong> |
Where,
r stands for rows and c stands for columns
Example: Following is the example for creating
2D array with 4 rows and 5 columns
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array=[[23,45,43,23,45],[45,67,54,32,45],[89,90,87,65,44],[23,45,67,32,10]] #display print(array) |
Output:
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[[23, 45, 43, 23, 45], [45, 67, 54, 32, 45], [89, 90, 87, 65, 44], [23, 45, 67, 32, 10]] |
Accessing the values
We can access the values using index position
Syntax:
We can get row value using [] operator
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array[row index] |
We can get column value using [][]
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Array[row index][column index] |
where,
- array is an input array
- row index is the row index position starts from 0
- column index is the column index position starts from 0 in a row.
Example:
In this example we are going to access the values using index positions
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#creare 2D array with 4 rows and 5 columns array=[[23,45,43,23,45],[45,67,54,32,45],[89,90,87,65,44],[23,45,67,32,10]] #display print(array) #get the first row print(array[0]) #get the third row print(array[2]) #get the first row third element print(array[0][2]) #get the third row forth element print(array[2][3]) |
Output:
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[[23, 45, 43, 23, 45], [45, 67, 54, 32, 45], [89, 90, 87, 65, 44], [23, 45, 67, 32, 10]] [23, 45, 43, 23, 45] [89, 90, 87, 65, 44] 43 65 |
We can also access elements using for loop
Syntax:
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for rows in the array: for columns in rows: print(columns) |
where,
- rows are used to iterate the row by row
- columns is used to iterate the values present in each row.
Example:
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Creare 2D array with 4 rows and 5 columns array=[[23,45,43,23,45],[45,67,54,32,45],[89,90,87,65,44],[23,45,67,32,10]] #use for loop to iterate the array for rows in array: for columns in rows: print(columns,end=" ") print() |
Output:
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23 45 43 23 45 45 67 54 32 45 89 90 87 65 44 23 45 67 32 10 |
Inserting the values into the two-dimensional array
Here we are going to insert values into two dimensional array using insert() function
Syntax:
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array.insert(index,[values]) |
where,
- the array is the input array
- the index is the row position to insert a particular row
- value are the values to be inserted into the array
Example: Insert to values in the array
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#creare 2D array with 4 rows and 5 columns array=[[23,45,43,23,45],[45,67,54,32,45],[89,90,87,65,44],[23,45,67,32,10]] #insert the row at 5 th position array.insert(2, [1,2,3,4,5]) #insert the row at 6 th position array.insert(2, [1,2,3,4,5]) #insert the row at 7 th position array.insert(2, [1,2,3,4,5]) #display print(array) |
Output:
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[[23, 45, 43, 23, 45], [45, 67, 54, 32, 45], [1, 2, 3, 4, 5], [1, 2, 3, 4, 5], [1, 2, 3, 4, 5], [89, 90, 87, 65, 44], [23, 45, 67, 32, 10]] |
Updating the values into the two-dimensional array
Here are two methods for updating values in the 2-D array(list).
You can update rows by using the following syntax
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array[row_index]= [values] |
You can update column values inside rows by using the following syntax
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array[row_index][column_index]= [values] |
Example:
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#creare 2D array with 4 rows and 5 columns array=[[23,45,43,23,45],[45,67,54,32,45],[89,90,87,65,44],[23,45,67,32,10]] #update row values in the 3rd row array[2]=[0,3,5,6,7] #update row values in the 5th row array[2]=[0,3,5,6,7] #update the first row , third column array[0][2]=100 #update the second row , third column array[1][2]=400 #display print(array) |
Output:
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[[23, 45, 100, 23, 45], [45, 67, 400, 32, 45], [0, 3, 5, 6, 7], [23, 45, 67, 32, 10]] |
Deleting the values from two-dimensional array
You can delete rows using the del function
Syntax:
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del array[index] |
where,
- the array is the input array
- index refers to the row index
Example:
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#creare 2D array with 4 rows and 5 columns array=[[23,45,43,23,45],[45,67,54,32,45],[89,90,87,65,44],[23,45,67,32,10]] #delete row values in the 3rd row del array[2] #delete row values in the 2nd row del array[1] #display print(array) |
Output:
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[[23, 45, 43, 23, 45], [23, 45, 67, 32, 10]] |
Get the size of two-dimensional array
You can get the size of the two-dimensional array using the line() function. It will return the number of rows in the array
Syntax:
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len(array) |
Example:
Get the length of the two-dimensional array
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#creare 2D array with 4 rows and 5 columns array=[[23,45,43,23,45],[45,67,54,32,45],[89,90,87,65,44],[23,45,67,32,10]] #display print(len(array)) |
Output:
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4 |
Summary:
Here are some important Array(list) Methods
| Method | Description | Syntax | Example | |
| Append(): | This method helps us to add an element at the end to an existing array. | array.append(value) | # Adding an element using append method to the end of an array array=[1,2,3] array.append(4) print(array) Output:[1,2,3,4] | |
| Clear(): | This method helps us to remove all the elements present in an array | array.clear() | # Removing all the elements from an array array=[1,2,3] array.clear()Output:[] | |
| Copy(): | This method helps us to copy the contents of an array to a new array | array1=array.copy() | #Copying the elements from an array to a new array array=[1,2,3] array1=[] array1=array.copy() print(array1) Output:[1,2,3] | |
| Count(): | This method helps us to count the no.of occurences of a an specified element in an array | array.count(element) | #Counting the no of times an element is present in an array array=[1,2,3] print(array.count(8)) Output: 0 | |
| Extend(): | This method helps us to extend an array beyond it’s consisting elements. | array.extend(array1) | #Extending an existing array with another array array=[1,2,3] array1=[4,5,6] array.extend(array1) print(array)Output: [1,2,3,4,5,6] | |
| Index(): | This method helps us to find the index of an element in an array | array.index(element) | #returing the index an element in an array array=[1,2,3] print(array.index(3))Output:2 | |
| Insert(): | This method helps us to insert elements into an array at specified index. | array.insert(index,element) | #Inserting an element at a specified index into an array array=[1,2,3] array.insert(2,4) print(array)Output:[1,2,4,3] | |
| Pop(): | This method helps us to remove an element at specified index | array.pop(index) | #Removing an element at specified index through pop method array=[1,2,3] array.pop(2) print(array)Output:[1,2] | |
| Remove(): | This method helps us to remove an particular matching element in an array. | array.remove(element) | array=[1,2,3] array.remove(2) print(array)Output:[1,3] | |
| Reverse(): | This method helps is to reverse the elements in an array. | array.reverse() | array=[1,2,3,4] array.reverse() print(array)Output:[4,3,2,1] |
