python random sample_Python的例外随机样例(Python random sample with exception)

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概述

Python的例外随机样例(Python random sample with exception)

我试图创建myList的示例，但i_除外。

我的尝试：

i_ = 'd'

myList = ['a','b','c','d','e']

myList = random.sample(myList, 3)

虽然上面的示例工作正常，但仍有可能从myList删除i_ 。

我想创建一个没有删除i_值的示例。

期望的输出：

任何包含3个项目的列表输出，包括i_ ，例如：

['a','d','e']

I'm attempting to create a sample of myList with the exception of i_.

My Attempt:

i_ = 'd'

myList = ['a','b','c','d','e']

myList = random.sample(myList, 3)

Although the above sample works fine, there is still a chance that i_ is removed from myList.

I would like to create a sample without the value of i_ being removed.

Desired Output:

Any list output containing 3 items including i_, e.g:

['a','d','e']

原文：https://stackoverflow.com/questions/46921831

更新时间：2019-10-27 22:04

最满意答案

只需从列表中抽取2个不带i_并稍后插入i_ ：

new_list = random.sample([i for i in myList if i != i_], 2)

new_list.insert(random.randrange(0, 3), i_)

但是这个假设i_只在您的列表中出现过一次 - 根据您的示例看起来似乎是合理的，但我想提一下完整性。此外，如果列表中有多个i_ ，我不确定期望的结果应该是什么。

你也可以使用命中和错过的方法来生成一个样本，直到你得到一个包含i_的样本：

new_list = []

while i_ not in new_list:

new_list = random.sample(myList, 3)

请注意，如果在样本中不太可能绘制i_ ，则这可能会非常慢。对于5个元素的3个样本来说，速度相当快，但如果您从1000个元素中抽取3个样本，速度可能会非常慢。

Just sample 2 values from the list without the i_ and insert i_ later:

new_list = random.sample([i for i in myList if i != i_], 2)

new_list.insert(random.randrange(0, 3), i_)

But this assumes that i_ occurs only once in your list - seems reasonable given your example but I wanted to mention this for completeness. Also I'm not sure what the desired result should be if there were multiple i_ in the list.

You could also use a hit&miss approach that generates a sample until you get one that contains i_:

new_list = []

while i_ not in new_list:

new_list = random.sample(myList, 3)

Note that this could be really slow if it's unlikely that i_ is drawn in the sample. For a 3-sample of 5 elements it's quite fast but it could be really slow if you draw a 3-sample from 1000 elements.

2017-10-25