Python: create category based on values in two arrays

Question

Say I have two lists:

arrayA = np.array([3,4,1,2,5,6,8,6,3])
arrayB = np.array([4,2,5,6,1,3,6,5,3])

which basically represents a point in 2D.

I want to get a label list that looks like:

listLael = [type1,type2,type1,type2,...]

that have the same length as arrayA and arrayB and

type1 if arrayA value >= 5 and arrayB value >= 5
type2 if eith arrayA or arrayB value < 5

I know that I can go through both array and get it but is there are fast and convenient way of doing this with numpy array?

Ashwini Chaudhary · Accepted Answer · 2015-07-16 20:20:33Z

2

Use numpy.where:

>>> np.where((arrayA >= 5) & (arrayB >= 5), 'type1', 'type2')
array(['type2', 'type2', 'type2', 'type2', 'type2', 'type2', 'type1',
       'type1', 'type2'],
      dtype='|S5')

answered Jul 16, 2015 at 20:20

Ashwini Chaudhary

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1 Comment

Yilun Zhang Over a year ago

Thanks! Exactly what I wanted.

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