Python: Select Only Parts of an input?

Sorry...I'm kind of a programming noob. I was looking at some problem sets online and I found THIS ONE. I wrote this much:

import random

powerball=random.randint(1,42)

a=random.randint(1,53)
b=random.randint(1,53)
c=random.randint(1,53)
d=random.randint(1,53)
e=random.randint(1,53)

(f,g,h,i,j)=x=input("Your 5 Chosen Numbers:")

My problem is that I don't know how to make the program print something li开发者_StackOverflow中文版ke "Please enter 5 numbers separated by only a comma" if more or less than five are entered. Also how would I do that if I wanted it to display a different message every other time they made that mistake?

Try this approach:

input_is_valid = False
while not input_is_valid:
    comma_separated_numbers = raw_input("Please enter a list of 5 numbers,separated by commas: ")
    numbers = [int(x.strip()) for x in comma_separated_numbers.split(",")]
    if len(numbers) != 5:
        print "Please enter exactly 5 numbers"
    else:
        input_is_valid = True

Looking at your link I'd say:

import random

while True:
    sets = input('how many sets? ')
    if type(sets) == int:
        break
    else:
        pass

for i in range(sets):
    ri = random.randint
    powerball = ri(1,42)
    other_numbers = sorted(ri(1,53) for i in range(5))
    print 'your numbers:','\t',other_numbers,'\t','powerball:','\t',powerball

It seems that's more or less what he asks from you. If I'm correct, you want the user to submit his series so to see if its one of the sets extracted (amirite?)

then it could be fine to do:

import random

while True:
    sets = input('how many sets? ')
    if type(sets) == int:
        break
    else:
        pass

while True:
    myset = raw_input('your 5 numbers:').split()
    if len(myset) != 5:
        print "just five numbers separated ny a space character!"
    else:
        myset = sorted(int(i) for i in myset)
        break


for i in range(sets):
    ri = random.randint
    powerball = ri(1,42)
    numbers = sorted(ri(1,53) for i in range(5))
    print 'numbers:','\t',numbers,'\t','powerball:','\t',powerball
    if numbers == myset:
        print "you won!" ##or whatever the game is about
    else:
        print "ahah you loser"

EDIT: beware this doesn't check on random generated numbers. So it happens one number can appear more than once in the same sequence. To practice you may try avoiding this behavior, doing so with a slow pace learning some python in the way it could be:

1. make a set out of a copy of the list "numbers" -- use set()
2. if its length is less than 5, generate another number
3. check if the new number is in the list
4. if it is, then append it to the list. if its not unique yet, GOTO point 1 :-)
5. sort the whole thing again
6. there you go

happy reading the docs!

My proposition:

import random
import sys

powerball=random.randint(1,42)

a=random.randint(1,53)
b=random.randint(1,53)
c=random.randint(1,53)
d=random.randint(1,53)
e=random.randint(1,53)


bla = ["\nPlease enter 5 numbers separated by only a comma : ",
       "\nPlease, I need 5 numbers separated by only a comma : ",
       "\nPLEASE, 5 numbers exactly : ",
       "\nOh gasp ! I said 5 numbers, no more nor less : ",
       "\n! By jove, do you know what 5 is ? : ",
       "\n==> I warn you, I am on the point to go off : "]

i = 0
while i<len(bla):

    x = raw_input(warn + bla[i])

    try:
        x = map(int, x.split(','))
        if len(x)==5:
            break
        i += 1

    except:
        print "\nTake care to type nothing else than numbers separated by only one comma.",

else:
    sys.exit("You wanted it; I go out to drink a beer : ")

(f,g,h,i,j)=x
print f,g,h,j,i

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Some explanation:

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for_stmt ::= "for" target_list "in" expression_list ":" suite ["else" ":" suite]

A break statement executed in the first suite terminates the loop without executing the else clause’s suite. A continue statement executed in the first suite skips the rest of the suite and continues with the next item, or with the else clause if there was no next item.

http://docs.python.org/reference/compound_stmts.html#index-801

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x = map(int, x.split(',')) means that the function int() is applied to each element of the iterable which is the second argument. Here the iterable is the list x.split(',') Hence, x is a list of 5 integers In Python 3, there is no more raw_input() , it has been replaced by input() that receives characters, as raw_input() in Python 2.

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