Python: Generate heat map

gistfile1.py

def rgb(r,g,b):  	# Just returns r, g, b in this case. Can be used to reformat RGB values if necessary.
	return r,g,b

def heat(min, max, val, type):		# Takes min and max values and the value to be heatmapped. Type is the look up table, see below.
	min = float(min)
	max = float(max)
	val = float(val)

	val = (val - min) / (max - min)		# normalize val to min and max

	r = float(0)
	g = float(0)
	b = float(0)

	if type == 'grey':
		r = val
		g = val
		b = val

	if type == 'greyinv':
		r = 1 - val
		g = 1 - val
		b = 1 - val

	if type == 'heat':		# green --> red
		if val <= 0.5:
			g = 1
			r = val / 0.5
			b = 0
	
		if val > 0.5:
			r = 1
			g = 2 + (val / (-(1 - 0.5)))
			b = 0

	elif type == 'greenbow':		# weird, but beautiful. Don't use for science.
		if val <= (1.0 / 3.0):
			r = 0
			g = val / (1.0 / 3.0)
			b = 1.0 - g
	
		if val > (1.0 / 3.0) and val <= (2.0 / 3.0):
			g = 1.0
			b = 0
			r = (val - (1.0 / 3.0)) / (1.0 / 3.0)

		if val > (2.0 / 3.0):
			g = 1.0 - (val - (2.0 / 3.0)) / (1.0 / 3.0)
			r = 1.0
			b = 0

	elif type == 'rainbow':			# rainbow colors
		if val < 0:
			r = 0
			g = 0
			b = 1

		if val >= 0 and val <= 0.25:
			r = 0
			g = val / 0.25
			b = 1
	
		if val > 0.25 and val <= 0.5:
			b = 1 - (val - 0.25) / 0.25
			g = 1
			r = 0

		if val > 0.5 and val <= 0.75:
			g = 1
			r = (val - 0.5) / 0.25
			b = 0
		
		if val > 0.75:
			r = 1
			g = 1 - ( (val - 0.75) / 0.25 )
			b = 0

	colours = rgb(r,g,b)
	return colours		# colours are returned as a fraction of 1. 1,1,1 = white; 0,0,0 = black.