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How to calculate frequency counts for unique values in an array with Python NumPy?

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Sometimes, we want to calculate frequency counts for unique values in an array with Python NumPy.

In this article, we’ll look at how to calculate frequency counts for unique values in an array with Python NumPy.

How to calculate frequency counts for unique values in an array with Python NumPy?

To calculate frequency counts for unique values in an array with Python NumPy, we can use the np.unique method with the return_counts argument set to True.

For instance, we write

import numpy as np

x = np.array([1,1,1,2,2,2,5,25,1,1])
unique, counts = np.unique(x, return_counts=True)
a = np.asarray((unique, counts)).T

to call np.unique with array x and return_counts set to True.

Then we combine the unique values and its counts into a single array with nested arrays that has the unique value with its count inside.

Conclusion

To calculate frequency counts for unique values in an array with Python NumPy, we can use the np.unique method with the return_counts argument set to True.

By John Au-Yeung

Web developer specializing in React, Vue, and front end development.

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