sorting floats numerically - not in ascii order - in python

This might sound like a silly question, but I've tried to find an answer that works without much success. I've got a list of lists:

for v in sorted(list):
    print v


[885.1, 12824]
[885.1, 19843]
[885.11, 开发者_如何学C1319]
[885.12, 1155]
[885.13, 12844]
[885.14, 33602]
[885.15, 11324]
[885.16, 44040]
[885.2, 119283]
[885.3, 8424]

I've iterated through my list using the sorted function - however that brings up the items in ASCII order as above - can they be sorted as floats in a human readable order? ie:

[885.1, 19843]
[885.2, 119283]
[885.3, 8424]
[885.11, 1319]
[885.12, 1155]
[885.13, 12844]
[885.14, 33602]
[885.15, 11324]
[885.16, 44040]

Do I need to create an index of somekind? Convert my floats to ints? Any help much appreciated.

David.

convert the float to string first and split it by ".":

sorted(a, key=lambda x:map(int, str(float(x[0])).split(".")))

This is called a "natsort" (natural sort). A quick google on it gives me this: http://www.skynet.ie/~caolan/Packages/python-natsort.html (haven't tried it though). Maybe it helps you.

^{Oh and that's not necessarily ASCII sort, it's just the number order, you know, like the real axis}

You need to give sorted a comparison function. Something like the following:

sorted(list, cmp=lambda x, y: cmp(x[0], y[0]))

Just write the function you need for what you want and plug it in.

You'll probably want something like a reverse radix sort.

This is kind of a hack, but:

a = [
    [885.1, 19843],
    [885.1, 12824],
    [885.11, 1319],
    [885.12, 1155],
    [885.13, 12844],
    [885.14, 33602],
    [885.15, 11324],
    [885.16, 44040],
    [885.2, 119283],
    [882.8, 8424],
    [882.75, 8424],
    [885.3, 8424]
]

for v in sorted(a, key=lambda t: str(t[0]).split(".")[0] + ("%05d" % int(str(t[0]).split(".")[1])) + "," + str(t[1])):
    print v

Result is

[882.8, 8424]
[882.75, 8424]
[885.1, 12824]
[885.1, 19843]
[885.2, 119283]
[885.3, 8424]
[885.11, 1319]
[885.12, 1155]
[885.13, 12844]
[885.14, 33602]
[885.15, 11324]
[885.16, 44040]

Disclaimer: this assumes at most 5 places after the decimal point. Adjust accordingly.