Creating 2D coordinates map in Python

问题:

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.

回答1:

Using itertools.product():

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

回答2:

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.

回答3:

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

1. 0.35903096199s
2. 0.461946964264s
3. 0.625234127045s

@F.J 0.27s

So yeah, his answer is the best.