According to the website http://www.andrewnoske.com/wiki/Code_-_heatmaps_and_color_gradients a heatmap is created by a color gradient which goes from blue to cyan then to green, over yellow to red. For realizing a function which takes as input a value between 0 .. 1 and returns as output the colorcode the inbetween values of two categories needs to be calculated. The Python function for doing so is a bit longer and takes 25 lines of code. In the referenced URL only the C++ version was given, I have reprogrammed the code.
During the creation of the sourcecode, a slider widget from TKinter was a great help. This allows the user to set a value between 0 and 1 interactively and observe what the return value of the function is.
Update: Sometthing is wrong with the embedded sourcecode. It seems, that the if statement (font) was formatted by the Blog engine a bit randomly.
import pygame
class Game:
def __init__(self):
self.pygamewindow = pygame.display.set_mode((500, 350), pygame.HWSURFACE | pygame.DOUBLEBUF)
self.fps=20 # 20
for i in range(1000000):
self.pygamewindow.fill(pygame.Color(255,255,255))
self.paintheatmap()
pygame.display.update()
pygame.time.wait(int(1000/self.fps))
def heatmapcolor(self,value):
# # value 0..1, returns colorcode (r,g,b)
# init gradient
gradient=[] # (value,r,g,b)
gradient.append((0.0, 0,0,1)) # blue
gradient.append((0.25, 0,1,1)) # cyan
gradient.append((0.5, 0,1,0)) # green
gradient.append((0.75, 1,1,0)) # yellow
gradient.append((1.0, 1,0,0)) # red
gradient.append((1.0, 1,0,0)) # red extra
# search base color
for i in range(len(gradient)):
diff=value-gradient[i][0]
if diff>=0 and diff<0 .25:="" font="" nbsp="">
break
# relative color
relvalue=(value-gradient[i][0])*1/0.25
red=(gradient[i+1][1]-gradient[i][1])*relvalue
red=(red+gradient[i][1])*255
green=(gradient[i+1][2]-gradient[i][2])*relvalue
green=(green+gradient[i][2])*255
blue=(gradient[i+1][3]-gradient[i][3])*relvalue
blue=(blue+gradient[i][3])*255
# result
result=(int(round(red)),int(round(green)),int(round(blue)))
return result
def paintheatmap(self):
grid_width,grid_height=12,50
maxstep=40
for i in range(maxstep):
value=i/maxstep # 0..1
temp=self.heatmapcolor(value)
col=pygame.Color(temp[0],temp[1],temp[2])
x=0+i*grid_width
pygame.draw.rect(self.pygamewindow, col, (x,3,grid_width,grid_height))
mygame=Game()
Update: Sometthing is wrong with the embedded sourcecode. It seems, that the if statement (font) was formatted by the Blog engine a bit randomly.
import pygame
class Game:
def __init__(self):
self.pygamewindow = pygame.display.set_mode((500, 350), pygame.HWSURFACE | pygame.DOUBLEBUF)
self.fps=20 # 20
for i in range(1000000):
self.pygamewindow.fill(pygame.Color(255,255,255))
self.paintheatmap()
pygame.display.update()
pygame.time.wait(int(1000/self.fps))
def heatmapcolor(self,value):
# # value 0..1, returns colorcode (r,g,b)
# init gradient
gradient=[] # (value,r,g,b)
gradient.append((0.0, 0,0,1)) # blue
gradient.append((0.25, 0,1,1)) # cyan
gradient.append((0.5, 0,1,0)) # green
gradient.append((0.75, 1,1,0)) # yellow
gradient.append((1.0, 1,0,0)) # red
gradient.append((1.0, 1,0,0)) # red extra
# search base color
for i in range(len(gradient)):
diff=value-gradient[i][0]
if diff>=0 and diff<0 .25:="" font="" nbsp="">
break
# relative color
relvalue=(value-gradient[i][0])*1/0.25
red=(gradient[i+1][1]-gradient[i][1])*relvalue
red=(red+gradient[i][1])*255
green=(gradient[i+1][2]-gradient[i][2])*relvalue
green=(green+gradient[i][2])*255
blue=(gradient[i+1][3]-gradient[i][3])*relvalue
blue=(blue+gradient[i][3])*255
# result
result=(int(round(red)),int(round(green)),int(round(blue)))
return result
def paintheatmap(self):
grid_width,grid_height=12,50
maxstep=40
for i in range(maxstep):
value=i/maxstep # 0..1
temp=self.heatmapcolor(value)
col=pygame.Color(temp[0],temp[1],temp[2])
x=0+i*grid_width
pygame.draw.rect(self.pygamewindow, col, (x,3,grid_width,grid_height))
mygame=Game()