创建带有随机放置的NaN的示例numpy数组 [英] Create sample numpy array with randomly placed NaNs
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问题描述
出于测试目的,我想用c
个随机放置的NaN创建一个M by N
numpy数组
For testing purposes, I'd like to create a M by N
numpy array with c
randomly placed NaNs
import numpy as np
M = 10;
N = 5;
c = 15;
A = np.random.randn(M,N)
A[mask] = np.nan
我在创建具有c
true元素的mask
时遇到问题,还是可以直接使用索引来完成?
I am having problems in creating a mask
with c
true elements, or maybe this can be done with indices directly?
推荐答案
您可以使用 .ravel()
),就像这样-
You can use np.random.choice
with the optional replace=False
for random selection without replacement
and use those on a flattened version of A
(done with .ravel()
), like so -
A.ravel()[np.random.choice(A.size, c, replace=False)] = np.nan
样品运行-
In [100]: A
Out[100]:
array([[-0.35365726, 0.26754527, -0.44985524, -1.29520237, 2.01505444],
[ 0.01319146, 0.65150356, -2.32054478, 0.40924753, 0.24761671],
[ 0.3014714 , -0.80688589, -2.61431163, 0.07787956, 1.23381951],
[-1.70725777, 0.07856845, -1.04354202, -0.68904925, 1.07161002],
[-1.08061614, 1.17728247, -1.5913516 , -1.87601976, 1.14655867],
[ 1.12542853, -0.26290025, -1.0371326 , 0.53019033, -1.20766258],
[ 1.00692277, 0.171661 , -0.89646634, 1.87619114, -1.04900026],
[ 0.22238353, -0.6523747 , -0.38951426, 0.78449948, -1.14698869],
[ 0.58023183, 1.99987331, -0.85938155, 1.4211672 , -0.43369898],
[-2.15682219, -0.6872121 , -1.28073816, -0.97523148, -2.27967001]])
In [101]: A.ravel()[np.random.choice(A.size, c, replace=False)] = np.nan
In [102]: A
Out[102]:
array([[ nan, 0.26754527, -0.44985524, nan, 2.01505444],
[ 0.01319146, 0.65150356, -2.32054478, nan, 0.24761671],
[ nan, -0.80688589, nan, nan, 1.23381951],
[ nan, nan, -1.04354202, -0.68904925, 1.07161002],
[-1.08061614, 1.17728247, -1.5913516 , nan, 1.14655867],
[ 1.12542853, nan, -1.0371326 , 0.53019033, -1.20766258],
[ nan, 0.171661 , -0.89646634, nan, nan],
[ 0.22238353, -0.6523747 , -0.38951426, 0.78449948, -1.14698869],
[ 0.58023183, 1.99987331, -0.85938155, nan, -0.43369898],
[-2.15682219, -0.6872121 , -1.28073816, -0.97523148, nan]])
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