如何使用numpy从列表中随机选择n个元素？

发布时间：2020-12-20 11:54:19 所属栏目：Python 来源：网络整理

导读：我有一个向量列表： import numpy as np num_dim,num_data = 10,5 data = np.random.rand(num_data,num_dim) dataarray([[ 0.0498063,0.18659463,0.30563225,0.99681495,0.35692358,0.47759707,0.85755606,0.39373145,0.54677259,0.5168117 ],[ 0.18034536,0

我有一个向量列表：

>>> import numpy as np
>>> num_dim,num_data = 10,5
>>> data = np.random.rand(num_data,num_dim)
>>> data
array([[ 0.0498063,0.18659463,0.30563225,0.99681495,0.35692358,0.47759707,0.85755606,0.39373145,0.54677259,0.5168117 ],[ 0.18034536,0.25935541,0.79718771,0.28604057,0.17165293,0.90277904,0.94016733,0.15689765,0.79758063,0.41250143],[ 0.80716045,0.84998745,0.17893211,0.36206016,0.69604008,0.27249491,0.92570247,0.446499,0.34424945,0.08576628],[ 0.35311449,0.67901964,0.71023927,0.03120829,0.72864953,0.60717032,0.8020118,0.36047207,0.46362718,0.12441942],[ 0.1955419,0.02702753,0.76828842,0.5438226,0.69407709,0.20865243,0.12783666,0.81486189,0.95583274,0.30157658]])

从数据中,我需要随机选择3个向量,我可以用：

>>> import random
>>> random.sample(data,3)
[array([ 0.80716045,0.08576628]),array([ 0.18034536,0.41250143]),array([ 0.35311449,0.12441942])]

我在http://docs.scipy.org/doc/numpy/reference/routines.random.html检查了文档,我无法弄清楚numpy中是否存在random.sample()这样的功能.

numpy.random.sample()与random.sample()不一样吗？

在numpy中是否存在random.sample()的等价性？

解决方法

正如@ayhan所证实的那样,可以这样做：

>>> data[np.random.choice(len(data),size=3,replace=False)]
array([[ 0.80716045,0.30157658]])

从docs：

numpy.random.choice(a,size=None,replace=True,p=None)

Generates a random sample from a given 1-D array

np.random.choice(data,size = 3,replace = False)从数据的索引列表中选择3个元素而不进行替换.

然后data […]对索引进行切片并检索用np.random.choice选择的索引.

（编辑：李大同）

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