Transform an integer into dummies vector in python

Question

Hi there!
I m working on python with pandas' get_dummies function and I try to transform an int into a vector like for example with a 5 categories feature :
1 -> [1,0,0,0,0]
2 -> [0,1,0,0,0]
...
Does a function exist for that? If not I can built a function but I just ask before reinventing the wheel.

Thanks !

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score 3 · Answer 1 · answered Jan 18 '18 at 18:49

3

Just cast the relevant Series to a string and then use get_dummies as usual.

pd.get_dummies(df['col'].astype(str))

answered Jan 18 '18 at 18:49

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Sqoshu · Answer 2 · 2018-01-16T15:02:31.090

I think it's so easy you should just write a simple function to do that, instead of asking. Here is one of countless ways to do this.

import numpy as np
    def get_dumm(lenn, num):
        arr = np.zeros(lenn, dtype='bool_') #replace type with 'int8' if needed
        arr[num - 1] = True #replace True with 1 if type of arr is 'int8'
        return arr
get_dumm(5,3)

Output:

array([False, False, True, False, False], dtype=bool)

Or if you use int8:

array([0, 0, 1, 0, 0], dtype=int8)

Transform an integer into dummies vector in python

2 Answers2