Pyhton Loop

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April 23rd, 2004, 10:15 AM

luckyboy

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Pyhton Loop

Hi
I am new to python infact programming. I am trying to write a programme which will pick 6 random numbers between 1 to 50 but no duplicate numbers and not using append function.

Here is something i wrote

import sys
import random
array=[]
#array=[55,65,1,89,10,54,1,258,2]
for i in range(5):

# storing Random numbers to an array
temp= random.randrange(1,50)
array+=[temp]
#print array

# random number(1-49) Validation (pick 6 different numbers) i #am stuck here
if temp == array[i]:
temp =random.randrange(1,50)
array+=[temp]

#Bubble sort(Ascending order)
for y in range(len(array)-1,0,-1):
for x in range(y):
if array[x]> array[x+1]:
array[x],array[x+1]=array[x+1],array[x]

# Displaying Random numbers in order (working)
for v in array:
print v,

Can someone help
Thanks
Luckyboy

April 23rd, 2004, 10:22 AM

luckyboy

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Quote:

Originally Posted by luckyboy

April 23rd, 2004, 01:50 PM

Strike

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Here's how I would do it, though I don't understand the restriction on not using .append()..

Code:

import random

picked_numbers = []

for i in range(6):
    newnum = random.randrange(1,50)
    while newnum in picked_numbers:
        newnum = random.randrange(1,50)
    picked_numbers += [newnum]

for num in picked_numbers:
    print num,

Normally instead of

Code:

picked_numbers += [newnum]

you'd just do

Code:

picked_numbers.append(newnum)

as it's more efficient.

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April 23rd, 2004, 05:38 PM

luckyboy

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Python loop

Hi it's working
Thank you strike

April 23rd, 2004, 06:39 PM

DevCoach

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This problem is discussed at length in the book 'Programming Pearls' by Jon Bentley, which I recommend that anyone who is serious about programming should read.

Here is an alternative way. Create a list with the numbers 1-50 in it, shuffle it, and gets the first six elements

Code:

>>> import random
>>> numbers = range(1, 51)
>>> random.shuffle(numbers)
>>> numbers[:6]
[48, 16, 4, 40, 35, 9]

This is fine for a small list of 50, but if you wanted a random number from the set of 1..1,000,000,000, then it would create an array with a billion elements, and throw away a billion minus six of them. In that case I would go to the book I mentioned and use an alternative algorithm.

Dave - The Developers' Coach

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