How to make a list of n numbers in Python and randomly select any number

Question

I have taken a count of something and it came out to N   Now I would like to have a list  containing 1 to N numbers in it   Example   N   5  then  count list    1  2  3  4  5   Also  once I have created the list  I would like to randomly select a number from that list and use that number   After that I would like to select another number from the remaining numbers of the list  N-1  and then use that also   This goes on it the list is empty

User · Accepted Answer

You can create the enumeration of the elements by something like this:

mylist = list(xrange(10))

Then you can use the random.choice function to select your items:

import random
...
random.choice(mylist)

As Asim Ihsan correctly stated, my answer did not address the full problem of the OP. To remove the values from the list, simply list.remove() can be called:

import random
...
value = random.choice(mylist)
mylist.remove(value)

As takataka pointed out, the xrange builtin function was renamed to range in Python 3.

User · Answer

You don t need to count stuff if you want to pick a random element  Just use random choice   and pass your iterable   import random items     foo    bar    baz   print random choice items    If you really have to count them  use random randint 1  count 1

User · Answer

Create the list  edited    count list   range 1  N 1    Select random element   import random random choice count list

User · Answer

After that I would like to select another number from the remaining numbers of the list  N-1  and then use that also    Then you arguably do not really want to create a list of numbers from 1 to N just for the purpose of picking one  why not just ask for a random number in that range directly  instead of explicitly creating it to choose from    but instead to shuffle such a list  Fortunately  the random module has you covered for this  too  just use random shuffle   Of course  if you have a huge list of numbers and you only want to draw a few  then it certainly makes sense to draw each using random choice and remove it   But    why do you want to select numbers from a range  that corresponds to the count of some items  Are you going to use the number to select one of the items  Don t do that  that s going out of your way to make things too complicated  If you want to select one of the items  then do so directly - again with random choice

User · Answer

As for the first part    gt  gt  gt  N   5  gt  gt  gt  count list    i 1 for i in xrange N    gt  gt  gt  count list  1  2  3  4  5   gt  gt  gt    As for the second  read 9 6  random     Generate pseudo-random numbers    gt  gt  gt  from random import choice  gt  gt  gt  a   choice count list   gt  gt  gt  a 1  gt  gt  gt  count list remove a   gt  gt  gt  count list  2  3  4  5    That s the general idea   By the way  you may also be interested in reading Random selection of elements in a list  with no repeats  Python recipe    There are a few implementations of fast random selection

User · Answer

You can try this code  import random N   5 count list   range 1 N 1  random shuffle count list   while count list      value   count list pop         do whatever you want with  value

User · Answer

Maintain a set and remove a randomly picked-up element  with choice  until the list is empty   s   set range 1  6   import random  while len s   gt  0    s remove random choice list s      print s    Three runs give three different answers    gt  gt  gt  set  1  3  4  5   set  3  4  5   set  3  4   set  4   set      gt  gt  gt  set  1  2  3  5   set  2  3  5   set  2  3   set  2   set       gt  gt  gt  set  1  2  3  5   set  1  2  3   set  1  2   set  1   set

User · Answer

You can use   import random random choice range n     or   random choice range 1 n 1     if you want it from 1 to n and not from 0

[python] How to make a list of n numbers in Python and randomly select any number?

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