# How to get the size (e.g. number of elements) of a matrix with numpy in python ?

Published: December 16, 2020

Tags: Python; Numpy;

Examples of how to get the number of elements in an array (or matrix) with numpy in python

### Create a matrix

Let's create a simple matrix to illustrate how to get the number of elements

````import numpy as np`

`A = np.random.randint(5, size=(4, 6))`

`print(A)`
```

returns

````[[3 0 0 4 3 3]`
` [4 2 3 4 2 2]`
` [0 1 1 4 1 0]`
` [4 3 0 0 3 3]]`
```

### Get the number of elements using size

To get the number of elements in the matrix A, a solution is to use the method size:

````print(A.size)`

`24`
```

### Get the number of elements using shape

````print(A.shape[0]*A.shape[1])`

`24`
```

### Get the number of unique elements

To go further we can also get unique elements inside the matrix A:

````print(np.unique(A))`
```

returns

````[0 1 2 3 4]`
```

and then print the number for each unique element:

````for e in np.unique(A):`
`    print('Number of {}: '.format(e), A[A==e].size)`
```

returns

````Number of 0:  6`
`Number of 1:  3`
`Number of 2:  3`
`Number of 3:  7`
`Number of 4:  5`
```