Creating 2D coordinates map in Python

Question

I'm not looking for solution, I'm looking for a better solution or just a different way to do this by using some other kind of list comprehension or something else.

I need to generate a list of tuples of 2 integers to get map coordinates like [(1, 1), (1, 2), ..., (x, y)]

So I have the following:

width, height = 10, 5

Solution 1

coordinates = [(x, y) for x in xrange(width) for y in xrange(height)]

Solution 2

coordinates = []
for x in xrange(width):
    for y in xrange(height):
        coordinates.append((x, y))

Solution 3

coordinates = []
x, y = 0, 0
while x < width:
    while y < height:
        coordinates.append((x, y))
        y += 1
    x += 1

Are there any other solutions? I like the 1st one most.

I'm fairly sure solution 1 is the best you can come up with. — hochl
– hochl, Commented Jan 31, 2012 at 16:11
At first I'm just writing them to the database to generate a RPG game map for 2D browser game. — aemdy
– aemdy, Commented Feb 1, 2012 at 9:16

Andrew Clark · Accepted Answer · 2012-01-31 16:12:42Z

17

Using itertools.product():

from itertools import product
coordinates = list(product(xrange(width), xrange(height)))

answered Jan 31, 2012 at 16:12

Andrew Clark

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3 Comments

cheeken Over a year ago

itertools is a computational saviour.

asthasr Over a year ago

+1. I would put it in a function, so that you can just pass in width and height and get the list back.

aemdy Over a year ago

Well, I've just done some testing and got the following: creating a generator by list comprehension without [] is the fastest way, but if we are looping through the data afterwards then your method is much faster. Thanks!:)

senderle · Accepted Answer · 2012-01-31 16:26:22Z

6

The first solution is elegant, but you could also use a generator expression instead of a list comprehension:

((x, y) for x in range(width) for y in range(height))

This might be more efficient, depending on what you're doing with the data, because it generates the values on the fly and doesn't store them anywhere.

This also produces a generator; in either case, you have to use list to convert the data to a list.

>>> list(itertools.product(range(5), range(5)))
[(0, 0), (0, 1), (0, 2), (0, 3), (0, 4), (1, 0), (1, 1), (1, 2), 
 (1, 3), (1, 4), (2, 0), (2, 1), (2, 2), (2, 3), (2, 4), (3, 0), 
 (3, 1), (3, 2), (3, 3), (3, 4), (4, 0), (4, 1), (4, 2), (4, 3), (4, 4)]

Note that if you're using Python 2, you should probably use xrange, but in Python 3, range is fine.

edited Jan 31, 2012 at 16:26

answered Jan 31, 2012 at 16:13

senderle

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2 Comments

Niklas R Over a year ago

Using xrange in the itertools.product class would be more memory efficient, like F.J. did.

senderle Over a year ago

@NiklasR, assuming this is Python 2. If it's Python 3, xrange no longer exists. Adding a note though.

Zenon · Accepted Answer · 2012-01-31 22:19:28Z

-1

UPDATED: Added @F.J. answer in the benchmark

The first implementation is the most pythonic way, and seems to be the fastest, too. Using 1000 for each, width and height, I register execution-times of

0.35903096199s
0.461946964264s
0.625234127045s

@F.J 0.27s

So yeah, his answer is the best.

edited Jan 31, 2012 at 22:19

answered Jan 31, 2012 at 16:20

Zenon

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1 Comment

LWZ Over a year ago

I assume the first implementation is F.J.'s itertools solution? And you should provide better descriptions for the numbers.

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