[英]Numpy array with different standard deviation and mean per row
I have a pandas data frame with two columns.我有一个包含两列的熊猫数据框。 They represent the mean and the standard deviation.
它们代表平均值和标准偏差。
How can I perform vectorized sampling?如何执行矢量化采样? I want to sample 1 observation per row.
我想每行采样 1 个观察值。
import numpy as np
import pandas as pd
rng = np.random.RandomState(0)
#n_points = 4_000_000
n_points = 10
d_dimensions = 2
X = rng.random_sample((n_points, d_dimensions))
df = pd.DataFrame(X)
display(df.head())
df['raondomized'] = df.apply(lambda x: np.random.normal(x[0], x[1], 1), axis = 1)
df.head()
It is very slow when the number of records increases.当记录数增加时,速度很慢。
Numpy array with different standard deviation per row
每行具有不同标准偏差的Numpy数组
np.random.seed(444) arr = np.random.normal(loc=0., scale=[1., 2., 3.], size=(1000, 3)).T print(arr.mean(axis=1)) # [-0.06678394 -0.12606733 -0.04992722] print(arr.std(axis=1)) # [0.99080274 2.03563299 3.01426507]
show how to perform vectorized sampling with equal means - how can this be changed to support different means just like my naive version using apply
, but faster?展示如何以相同的方式执行矢量化采样 - 如何将其更改为支持不同的方式,就像我使用
apply
天真版本一样,但速度更快?
A: A:
np.random.normal(df[0], df[1], 1)
only returns a single scalar value, even though multiple means/standard deviations are specified.即使指定了多个均值/标准差,也仅返回单个标量值。
df['raondomized'] = np.random.normal(df[0], df[1])
重要的是不要指定元素的数量。
How about怎么样
np.random.normal(df[0], df[1], len(df))
You can also specify how many run per specification (say 1000),您还可以指定每个规范的运行次数(例如 1000),
np.random.normal(df[0], df[1], (1000, len(df)))
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