python - Select n random number from a sorted list of numbers -

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i have list of numbers in sorted order. there may gaps between consecutive numbers. wrote following code find 50k random numbers list, takes time. there efficient version this? 

def selectnrandomvalsfromalist(mylist, n):     retval = []     randomchoice = random.choice     mylistremove = mylist.remove     retvalappend = retval.append     in range(n):         value = randomchoice(mylist)         mylistremove(value)         retvalappend(value)     return(retval)    mylist = range(2000000) n =50000 selectnrandomvalsfromalist(mylist,n)

don't reinvent wheel. use random.sample:

return k length list of unique elements chosen population sequence. used random sampling without replacement.

>>> import random >>> l = range(20) >>> random.sample(l, 10) [6, 15, 13, 3, 2, 4, 14, 17, 7, 10]

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