Dax Feliz Dax Feliz - 1 month ago 10
Python Question

Removing nan values from an array

I want to figure out how to remove nan values from my array. It looks something like this:

x = [1400, 1500, 1600, nan, nan, nan ,1700] #Not in this exact configuration


I'm relatively new to python so I'm still learning. Any tips?

Answer

If you're using numpy for your arrays, you can also use

x = x[numpy.logical_not(numpy.isnan(x))]

Equivalently

x = x[~numpy.isnan(x)]

[Thanks to chbrown for the added shorthand]

Explanation

The inner function, numpy.isnan returns a boolean/logical array which has the value True everywhere that x is not-a-number. As we want the opposite, we use the logical-not operator, ~ to get an array with Trues everywhere that x is a valid number.

Lastly we use this logical array to index into the original array x, to retrieve just the non-NaN values.