How make an area iterable by each point in python

Question

Hello I'm trying to make a class that represents an area that can be iterated with a for ... in loop. I know that it can be done with two for loops, but I'm trying to understand generators in general.

I'm using Python 3

I've written this but doesn't work:

class Area:
    def __init__(self, width, height):
        self.width = width
        self.height = height

    def __iter__(self):
        # my best try, clearly I don't understand 
        # something about generators
        for x in range(0, self.width):
            for y in range(0, self.height):
                yield x, y 

area = Area(2, 3)
for x, y in area:
    print("x: {}, y: {}".format(x, y))

# I want this to output something like:
#  x: 0, y: 0 
#  x: 1, y: 0
#  x: 0, y: 1
#  x: 1, y: 1
#  x: 0, y: 2
#  x: 1, y: 2

Thanks you

I tried your code and it works almost like desired. What exactly "doesn't work"? — Ilya V. Schurov, Nov 20 '16 at 02:09
Try iterating over the points with just two `for` loops, no `Area` class involved. That might make it more apparent what you're doing wrong. — user2357112, Nov 20 '16 at 02:11
Thank you all, I think I have another error in my code. I've made a simplification for my question and this code works. Excuse me, it's my fault. — Carlos Gant, Nov 20 '16 at 02:14

score 1 · Accepted Answer · edited May 23 '17 at 12:07

here is a simple example how it works:

class Fib:
    def __init__(self, max):
        self.max = max

    def __iter__(self):
        // The variables you need for the iteration, to store your
        // values
        self.a = 0
        self.b = 1
        return self

    def __next__(self):
        fib = self.a
        if fib > self.max:
            raise StopIteration  // This is no error. It means, that
                                 // The iteration stops here.
        self.a, self.b = self.b, self.a + self.b
        return fib

I hope this helps. I don't understand what you want to do with your class. There is a good tutorial here.

Michael

How make an area iterable by each point in python

1 Answers1