Python：在列表中生成元组

Question

Is there an elegant/alternative way to do this:

allcolors = []
for Red in range(0,256):
    for Green in range(0,256):
        for Blue in range(0,256):
            allcolors.append((Red,Green,Blue))

I was thinking something like (Pseudo code) :

[Red for Red in [Green for Green in [Blue for Blue in range(0,256)]]]

Answer 1

This will work:

allcolors = [(Red,Green,Blue) for Red in range(0,256) for Green in range(0,256) for Blue in range(0,256)]

In list comprehensions , the for ... in ... clauses go in the same order as if they were for-loops.

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Secondly, the 0's passed to range are redundant here since range starts at 0 by default. In other words, you can write the same thing more consicely like so:

allcolors = [(Red,Green,Blue) for Red in range(256) for Green in range(256) for Blue in range(256)]

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Also, if you are on Python 2.x, you should use xrange instead of range :

allcolors = [(Red,Green,Blue) for Red in xrange(256) for Green in xrange(256) for Blue in xrange(256)]

This is because xrange returns an iterator instead of constructing an unnecessary list like range .

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Finally, the convention for Python variable names is that they be lowercase. Meaning, Red , Green , and Blue should be named red , green , and blue . :)

Answer 2

您可以尝试使用列表理解 ：

allcolors = [(r, g, b) for r in xrange(0, 256) for g in xrange(0, 256) for b in xrange(0, 256)]

Answer 3

Something like this:

allcolors = [ (Red,Green,Blue) for Red in range(0,256) for Green in range(0,256) for Blue in range(0,256) ]

You can transform your loop into a list comprehension by thinking about it like this:

[(Red,Green,Blue) for Red in range(0,256)
                     for Green in range(0,256)
                         for Blue in range(0,256) ]