# How to choose elements from the list with different probability using NumPy?

• Last Updated : 01 Oct, 2020

We will see How to use numpy.random.choice() method to choose elements from the list with different probability.

Syntax: numpy.random.choice(a, size=None, replace=True, p=None)

Output: Return the numpy array of random samples.

Note: parameter p is probabilities associated with each entry in a(1d-array). If not given the sample assumes a uniform distribution over all entries in a.

Now, let’s see the examples:

Example 1:

## Python3

 `# import numpy library``import` `numpy as np`` ` `# create a list``num_list ``=` `[``10``, ``20``, ``30``, ``40``, ``50``]`` ` `# uniformly select any element``# from the list``number ``=` `np.random.choice(num_list)`` ` `print``(number)`

Output:

```50
```

Example 2:

## Python3

 `# import numpy library``import` `numpy as np`` ` `# create a list``num_list ``=` `[``10``, ``20``, ``30``, ``40``, ``50``]`` ` `# choose index number-3rd element``# with 100% probability and other``# elements probability set to 0``# using p parameter of the``# choice() method so only``# 3rd index element selected``# every time in the list size of 3.``number_list ``=` `np.random.choice(num_list, ``3``,``                          ``p ``=` `[``0``, ``0``, ``0``, ``1``, ``0``])`` ` `print``(number_list)`

Output:

```[40 40 40]
```

In the above example, we want only to select the 3rd index element from the given list every time.

Example 3:

## Python3

 `# import numpy library``import` `numpy as np`` ` `# create a list``num_list ``=` `[``10``, ``20``, ``30``, ``40``, ``50``]`` ` ` ` `# choose index number 2nd & 3rd element``# with  50%-50% probability and other``# elements probability set to 0``# using p parameter of the``# choice() method so 2nd & ``# 3rd index elements selected``# every time in the list size of 3.``number_list ``=` `np.random.choice(num_list, ``3``,``                          ``p ``=` `[``0``, ``0``, ``0.5``, ``0.5``, ``0``])`` ` `print``(number_list)`

Output:

```[30 40 30]
```

In the above example, we want to select 2nd & 3rd index elements from the given list every time.

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