# How do you find the identity matrix in python?

numpy.identity(n, dtype=None, *, like=None)[source]#

Return the identity array.

The identity array is a square array with ones on the main diagonal.

Parametersnint

Number of rows (and columns) in n x n output.

dtypedata-type, optional

Data-type of the output. Defaults to `float`.

likearray_like, optional

Reference object to allow the creation of arrays which are not NumPy arrays. If an array-like passed in as `like` supports the `__array_function__` protocol, the result will be defined by it. In this case, it ensures the creation of an array object compatible with that passed in via this argument.

New in version 1.20.0.

Returnsoutndarray

n x n array with its main diagonal set to one, and all other elements 0.

Examples

```>>> np.identity(3)
array([[1.,  0.,  0.],
[0.,  1.,  0.],
[0.,  0.,  1.]])
```

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numpy.identity(n, dtype = None) : Return a identity matrix i.e. a square matrix with ones on the main diagonal.

```Parameters :
n     : [int] Dimension n x n of output array
dtype : [optional, float(by Default)] Data type of returned array.  ```
```Returns :
identity array of dimension n x n,  with its main diagonal set to one, and all other elements 0.```

Example:

## Python

`import` `numpy as geek`

`b ``=` `geek.identity(``2``, dtype ``=` `float``)`

`print``(``"Matrix b : \n"``, b)`

`a ``=` `geek.identity(``4``)`

`print``(``"\nMatrix a : \n"``, a)`

Output :

```Matrix b :
[[ 1.  0.]
[ 0.  1.]]

Matrix a :
[[ 1.  0.  0.  0.]
[ 0.  1.  0.  0.]
[ 0.  0.  1.  0.]
[ 0.  0.  0.  1.]]```

Note :
These codes won’t run on online-ID. Please run them on your systems to explore the working.
This article is contributed by Mohit Gupta_OMG 😀. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to . See your article appearing on the GeeksforGeeks main page and help other Geeks.

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Introduction to Identity Matrix :

The dictionary definition of an Identity Matrix is a square matrix in which all the elements of the principal or main diagonal are 1’s and all other elements are zeros. In the below image, every matrix is an Identity Matrix.

In linear algebra, this is sometimes called as a Unit Matrix, of a square matrix (size = n x n) with ones on the main diagonal and zeros elsewhere. The identity matrix is denoted by “ I “. Sometimes U or E is also used to denote an Identity Matrix.
A property of the identity matrix is that it leaves a matrix unchanged if it is multiplied by an Identity Matrix.

Examples:

```Input  : 2
Output : 1 0
0 1

Input :  4
Output : 1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1
The explanation is simple. We need to make all
the elements of principal or main diagonal as
1 and everything else as 0.```

Program to print Identity Matrix :
The logic is simple. You need to the print 1 in those positions where row is equal to column of a matrix and make all other positions as 0.

## Python3

`def` `Identity(size):`

`    ``for` `row ``in` `range``(``0``, size):`

`        ``for` `col ``in` `range``(``0``, size):`

`            ``if` `(row ``=``=` `col):`

`                ``print``(``"1 "``, end``=``" "``)`

`            ``else``:`

`                ``print``(``"0 "``, end``=``" "``)`

`        ``print``()`

`size ``=` `5`

`Identity(size)`

Output:

```1  0  0  0  0
0  1  0  0  0
0  0  1  0  0
0  0  0  1  0
0  0  0  0  1  ```

Time complexity: O(R*C) where R and C is no of rows and column in matrix respectively

Program to check if a given square matrix is Identity Matrix :

## Python3

`MAX` `=` `100``;`

`def` `isIdentity(mat, N):`

`    ``for` `row ``in` `range``(N):`

`        ``for` `col ``in` `range``(N):`

`            ``if` `(row ``=``=` `col ``and`

`                ``mat[row][col] !``=` `1``):`

`                ``return` `False``;`

`            ``elif` `(row !``=` `col ``and`

`                  ``mat[row][col] !``=` `0``):`

`                ``return` `False``;`

`    ``return` `True``;`

`N ``=` `4``;`

`mat ``=` `[[``1``, ``0``, ``0``, ``0``],`

`       ``[``0``, ``1``, ``0``, ``0``],`

`       ``[``0``, ``0``, ``1``, ``0``],`

`       ``[``0``, ``0``, ``0``, ``1``]];`

`if` `(isIdentity(mat, N)):`

`    ``print``(``"Yes "``);`

`else``:`

`    ``print``(``"No "``);`

Output:

`Yes`

Time complexity: O(N2) where N is number of rows and columns of matrix

Auxiliary Space: O(1)

### How do you display the identity matrix in Python?

Python Program to Print an Identity Matrix.
Take a value from the user and store it in a variable n..
Use two for loop where the value of j ranges between the values of 0 and n-1 and value of i also ranges between 0 and n-1..
Print the value of 1 when i is equal to j and 0 otherwise..

### How do you get an identity matrix in numpy?

Step 1: Import numpy. Step 2: Take dimensions as input from the user. Step 3: Print the identity matrix using numpy. identity() function.

### Which command is used for identity matrix?

I = eye( n , m ) returns an n -by- m matrix with ones on the main diagonal and zeros elsewhere. I = eye( sz ) returns an array with ones on the main diagonal and zeros elsewhere.

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