CODEWITHSUNDEEP
pythonalgorithmsortingcolors
NFicano
NFicano

Reputation: 1075

Sort (hex) colors to match rainbow

I have a list of colors represented in hex - I need to sort them to match the order of colors in a rainbow. - I could hardcode a sort order - but I feel there's a cleaner way.

Upvotes: 6

Views: 12811

Answers (4)

gaboroncancio
gaboroncancio

Reputation: 900

Modifying kindall answer to allow short color specifications in hex (e.g. #f0f, #005):

import colorsys

def get_hsv(hexrgb):
    hexrgb = hexrgb.lstrip("#")   # in case you have Web color specs
    lh = len(hexrgb)
    # Allow short and long hex codes
    r, g, b = (int(hexrgb[i:i+lh/3], 16) / 255.0 for i in xrange(0, lh, lh/3))
    return colorsys.rgb_to_hsv(r, g, b)

Now you can use the function to sort the list by hue:

color_list = ["#005", "#000500", "#500000"]
color_list.sort(key=get_hsv)
print color_list

>> ['#500000', '#000500', '#005']

Upvotes: 2

kindall
kindall

Reputation: 184465

Here's a function that, given a color specification in hex RGB, returns its HSV color:

import colorsys

def get_hsv(hexrgb):
    hexrgb = hexrgb.lstrip("#")   # in case you have Web color specs
    r, g, b = (int(hexrgb[i:i+2], 16) / 255.0 for i in xrange(0,5,2))
    return colorsys.rgb_to_hsv(r, g, b)

Now you can use this to sort your list of RGB hex colors by hue:

color_list = ["000050", "005000", "500000"]  # GBR
color_list.sort(key=get_hsv)
print color_list

By sorting using the entire HSV tuple, you ensure that colors that have no hue (i.e. grayscales) sort in a consistent place, and that colors with the same hue but different saturations/values sort in a consistent order relative to their more-saturated/valued counterparts.

You will still have something of a mess if colors vary widely by saturation (intensity) or value (brightness), but there's no getting around that.

Upvotes: 17

arx
arx

Reputation: 16904

The easiest thing to do is sort them in hue order.

Upvotes: 1

Yann Ramin
Yann Ramin

Reputation: 33197

Look up the HSV color representation: https://en.wikipedia.org/wiki/HSL_and_HSV

By sorting first by Hue, you can sort by perceived color. You can freely convert between RGB and HSV.

Upvotes: 5

Related Questions