从列表中随机选择50项写入文件

Question

到目前为止，我已经知道了如何导入文件、创建新文件和随机化列表

我无法从列表中随机选择50项写入文件

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')   

所以如果整个随机化文件是

example:

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

我想要3个文件（out|file1 | 2 | 3），第一个随机集为3，第二个随机集为3，第三个随机集为3（在本例中，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，最后的“4”将不包括在内，这很好

如何从我随机化的列表中选择50

更好的是，我怎么能从原始列表中随机选择50个呢？

Answer 1

我认为random.choice()是一个更好的选择

import numpy as np

mylist = [13,23,14,52,6,23]

np.random.choice(mylist, 3, replace=False)

该函数返回从列表中随机选择的3个值的数组

Answer 2

如果列表是随机排列的，你可以只取前50个

否则，请使用

import random
random.sample(the_list, 50)

random.sample帮助文本：

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)

Answer 3

选择随机项目的一个简单方法是先洗牌，然后切片

import random
a = [1,2,3,4,5,6,7,8,9]
random.shuffle(a)
print a[:4] # prints 4 random variables