[Tutor] A row of cards, but they're all red

[Danny Yoo]

> Could someone help me understand the output I'm getting from the snippet
> below? I thought I would get a nice row of cards, 13 reds, 13 blues,
> etc. But what I get is a row of all red cards. The rank is correct on
> the cards, but they are all red.


Hi Terry,


There is an issue with the loop here:

> for suit in suits:
>      for x, rank in enumerate(ranks):
>          cards.append([suit, rank, value[x], images[x]])

Let's assume for the moment that everything else is ok, and that images is
a list of fifty-two elements.  The loop above tries to associate each
individual image with a unique card.

Think about what values 'x' goes over in the loop, and you should see a
problem.  Again, try matching up the experience you're seeing --- all red
cards --- and try doing a "what if?" on the situation here.



Side note: you might find a funky operator called the "modulo" operator
very useful.  Here's what it looks like:

######
>>> for hour in range(24):
...     print hour, hour % 12
...
0 0
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
9 9
10 10
11 11
12 0
13 1
14 2
15 3
16 4
17 5
18 6
19 7
20 8
21 9
22 10
23 11
######

That is, "modulo" makes numbers "wrap" around.  More formally,

    m % n

ends up being the remainder if we divide m by n.  Believe it or not, this
can be very handy at times.  (Otherwise, why would I mention it here?
*grin*)  We can talk about this in more detail if you'd like.


Good luck to you!