#INPUT
#W1 W2 W3 W4
# 0  1  1  0
# 1  1  1  1
# 1  0  0  0
# 0  1  0  1
#
#For every row, randomly select single element that is 1 and make other ones 0
#Initial zeros stay zeros
#
#OUTPUT
#W1 W2 W3 W4
# 0  1  0  0
# 0  1  0  0
# 1  0  0  0
# 0  0  0  1

import pandas as pd
import numpy as np


df = pd.DataFrame({'w1': [0, 1, 1, 0],
                   'w2': [1, 1, 0, 1],
                   'w3': [1, 1, 0, 0],
                   'w4': [0, 1, 0, 1]})

#method 1
def choose_one(row):
    one = np.random.choice([i for i, v in enumerate(row) if v])
    return [0 if i != one else 1 for i in range(len(row))]

t, t.columns = df.apply(choose_one, axis=1).apply(pd.Series), df.columns

#method 2
idx = pd.DataFrame(np.stack(np.where(df==1))).T.groupby(0).apply(lambda x: x.sample(1)).values
t, t.values[idx[:, 0], idx[:, 1]] = pd.DataFrame(np.zeros(df.shape, dtype=np.int), columns=df.columns), 1