turn list of categorical variables into (0,1) list

问题

my problem: I have a list of categorical variables such as

import numpy as np
a = np.array(['A','A','B','B','C','C','C'])
unique_vars = {v: k for k, v in enumerate(np.unique(a))}
c = np.array([unique_vars[i] for i in a])

which yields:

array([0, 0, 1, 1, 2, 2, 2])

and I want to turn into:

res = [0,0, 1,1, 0,0,0]

in essence, at every "switch", the number has to be switched from 1 to 0.

回答1:

First off, you can get the unique IDs in a vectorized manner with np.unique and additional input argument return_inverse -

c = np.unique(a,return_inverse=1)[1]

Then, use modulus(..,2) to make the switches between 0 and 1 -

out = np.mod(c, 2)  # Or c%2

回答2:

Maybe you are looking something like this:

arr = ['A','A','B','B','C','C','C']

def get_switched_array(in_array, value):
    return [ 1 if v == value else 0 for v in in_array ]

print get_switched_array( arr, 'A')
print get_switched_array( arr, 'B')
print get_switched_array( arr, 'C')

which outputs:

[1, 1, 0, 0, 0, 0, 0]
[0, 0, 1, 1, 0, 0, 0]
[0, 0, 0, 0, 1, 1, 1]

来源：https://stackoverflow.com/questions/40931910/turn-list-of-categorical-variables-into-0-1-list