从列表中随机选择50个项目写入文件

Question

到目前为止，我已经弄清楚了如何导入文件，创建新文件以及使列表随机化。

我在从列表中随机选择50个项目以写入文件时遇到麻烦吗？

def randomizer(input,output1='random_1.txt',output2='random_2.txt',output3='random_3.txt',output4='random_total.txt'):

#Input file 
    query=open(input,'r').read().split()
    dir,file=os.path.split(input)

    temp1 = os.path.join(dir,output1)
    temp2 = os.path.join(dir,output2)
    temp3 = os.path.join(dir,output3)
    temp4 = os.path.join(dir,output4)


    out_file4=open(temp4,'w')

    random.shuffle(query)

    for item in query:
        out_file4.write(item+'\n')

因此，如果总随机文件为

example:

random_total = ['9','2','3','1','5','6','8','7','0','4']

我想要3个文件（out_file1 | 2 | 3），其中第一个随机集为3，第二个随机集为3，第三个随机集为3（在此示例中，但我要创建的文件应该有50个）

random_1 = ['9','2','3']
random_2 = ['1','5','6']
random_3 = ['8','7','0']

因此，不会包含最后一个“ 4”，这很好。

如何从随机选择的列表中选择50？

更好的是，如何从原始列表中随机选择50个？

Answer 1

如果列表是随机顺序的，则可以只取前50个。

否则，使用

import random
random.sample(the_list, 50)

random.sample 帮助文字：

sample(self, population, k) method of random.Random instance
    Chooses k unique random elements from a population sequence.

    Returns a new list containing elements from the population while
    leaving the original population unchanged.  The resulting list is
    in selection order so that all sub-slices will also be valid random
    samples.  This allows raffle winners (the sample) to be partitioned
    into grand prize and second place winners (the subslices).

    Members of the population need not be hashable or unique.  If the
    population contains repeats, then each occurrence is a possible
    selection in the sample.

    To choose a sample in a range of integers, use xrange as an argument.
    This is especially fast and space efficient for sampling from a
    large population:   sample(xrange(10000000), 60)