How to Calculate Mean, Variance and Std of a Matrix or ndArray?
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# How to Calculate Mean, Variance and Std of a Matrix or ndArray?

This recipe helps you Calculate Mean, Variance and Std of a Matrix or ndArray

0

## Recipe Objective

Statical analysis is very important part preprocessing. Have you tried to do it for matrix?

So this is the recipe on how we can can Calculate Mean, Variance and Std a Matrix or ndArray.

## Step 1 - Importing Library

``` import numpy as np ```

We have only imported numpy which is needed.

## Step 2 - Creating a matrix

We have created a matrix by using np.array with different values. ``` matrixA = np.array([[1, 2, 3, 23], [4, 5, 6, 25], [7, 8, 9, 28], [10, 11, 12, 41]]) ```

## Step 3 - Finding Mean, Median, Variance and Standard Deviation

We have calculated mean, median , variance and standard deviation by using numpy functions for a matrix. ``` print("Median: ", np.median(matrixA)) print("Mean: ", np.mean(matrixA)) print("Variance: ", np.var(matrixA)) print("Standrad Dev: ", np.std(matrixA)) ``` So the output comes as

```Median:  8.5

Mean:  12.1875

Variance:  118.27734375

```

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