[英]Replace percentage of True items in Boolean Numpy Array
I have a numpy array that maybe looks like:我有一个 numpy 数组,它可能看起来像:
matches = np.array([True, True, False, False, False])
I need to replace the True
values with True
or False
depending on a probability.我需要根据概率将True
值替换为True
或False
。 For example if the probability is 0.5 one or the other will get replaced with False
.例如,如果概率为 0.5,则其中一个将被替换为False
。 Actually each element will have the probability applied to it.实际上,每个元素都会应用概率。
So I have numpy where.所以我有 numpy 在哪里。 But I cant quite figure out how to do it:但我不知道该怎么做:
Where value == True
replace with random value.其中value == True
用随机值替换。
Assuming you want a uniform probability distribution假设你想要一个均匀的概率分布
import numpy as np
matches = np.array([True, True, False, False, False])
# Here you create an array with the same length as the number of True values in matches
random_values = np.random.uniform(low=0, high=100, size=(sum(matches)))
# Setting the threshold and checking which random values are lower.
# If they are higher or equal it returns False, if they are lower it returns True
threshold = 75
random_values_outcome = random_values < threshold
# Substituting the True entries in matches with corresponding entries from
# random_values_outcome
matches[matches == True] = random_values_outcome
This worked for me:这对我有用:
import numpy as np
import random
matches = np.array([True, True, False, False, False])
for position, value in np.ndenumerate(matches):
if value == True:
matches[position] = random.choice([True, False])
print(matches)
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