Decrease for loop by one

Chris Angelico rosuav at
Thu Jan 24 05:59:13 CET 2013

On Thu, Jan 24, 2013 at 3:39 PM, Milter Skyler <matt17 at> wrote:
> I made an array to check if the random integer already exists and then I send it to the else statement at which point I want to decrease x by 1 so that it doesn't count as one of the loops. In other languages this works...

A Python 'for' loop doesn't behave like that; you can't just edit the
loop counter. But take a step back: what are you actually trying to
accomplish? As I see it, you're trying to pick ten unique random
values in the range 1-12 inclusive. Try this:

random.sample(range(1,13),10) # note that range() stops *before* its second arg

That'll give you a list of those integers, and it's a lot safer and
more reliable than the try-fail-retry method. Your loop can become:

    for decimal_value in random.sample(range(1,13),10):
            egg = 'A%d.png' % (decimal_value)
            egg = wait(egg)

By the way, this line simply won't work:

x-1 = x

I think you mean:

x = x-1

But I strongly suggest you copy and paste directly rather than retype;
it's less error-prone.

Hope that helps!


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