Select 50 items from list at random to write to file

Question

So far I have figured out how to import the file  create new files  and randomize the list    I m having trouble selecting only 50 items from the list randomly to write to a file   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        So if the total randomization file was   example   random total     9   2   3   1   5   6   8   7   0   4     I would want 3 files  out file1 2 3  with the first random set of 3  second random set of 3  and third random set of 3  for this example  but the one I want to create should have 50   random 1     9   2   3   random 2     1   5   6   random 3     8   7   0     So the last  4  will not be included which is fine   How can I select 50 from the list that I randomized    Even better  how could I select 50 at random from the original list

User · Answer

One easy way to select random items is to shuffle then slice    import random a    1 2 3 4 5 6 7 8 9  random shuffle a  print a  4    prints 4 random variables

User · Answer

Say your list has 100 elements and you want to pick 50 of them in a random way  Here are the steps  to follow    Import the libraries Create the seed for random number generator  I have put it at 2 Prepare a list of numbers from which to pick up in a random way Make the random choices from the numbers list   Code   from random import seed from random import choice  seed 2  numbers    i for i in range 100    print numbers   for   in range 50       selection   choice numbers      print selection

User · Answer

I think random choice   is a better option   import numpy as np  mylist    13 23 14 52 6 23   np random choice mylist  3  replace False    the function returns an array of 3 randomly chosen values from the list

User · Answer

If the list is in random order  you can just take the first 50   Otherwise  use  import random random sample the list  50    random sample help text   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

[python] Select 50 items from list at random to write to file

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