CODEWITHSUNDEEP
python-3.xreplacefloating-point
Rangooski
Rangooski

Reputation: 873

Python: How to replace negative values with "0" in a matrix?

Let's say I have a matrix 

x = [[0.708, 0.000, -0.070],
[-0.004, 0.561, -0.088 ],
[ 0.001, -0.001 -0.023]]

I want to replace all the negative values if it begins -0.0 with 0.

Is there any way to do it python. Since my matrix is really big, it also need to be computationally efficient ?

Upvotes: 1

Views: 1030

Answers (1)

J91321
J91321

Reputation: 727

Easiest solution I would suggest is using numpy for handling any matrix operations so you won't have to reimplement the wheel. Maybe it would be worth looking into numpy masking operations, like masked_where

I'm not saying this is the most efficient solution, really don't know what you consider big matrix and what sort of efficiency you need, I would probably try several approaches, and compare them using profiler and decide which is best for you.

>>> import numpy
>>> x = numpy.array([1, 2, 3, -99, 5])
>>> c = numpy.ma.masked_where(x < 0, x, copy=False)
>>> c
masked_array(data = [1 2 3 -- 5],
             mask = [False False False  True False],
       fill_value = 999999)

>>> x2 = c.filled(0)
>>> x2
array([1, 2, 3, 0, 5])

Upvotes: 4

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