geospatialpython/DensityProfiler_pure.py at master · GeospatialPython/geospatialpython · GitHub

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import random

import shapefile

import pngcanvas

def pip(x,y,poly):

n = len(poly)

inside = False

p1x,p1y = poly[0]

for i in range(n+1):

p2x,p2y = poly[i % n]

if y > min(p1y,p2y):

if y <= max(p1y,p2y):

if x <= max(p1x,p2x):

if p1y != p2y:

xinters = (y-p1y)*(p2x-p1x)/(p2y-p1y)+p1x

if p1x == p2x or x <= xinters:

inside = not inside

p1x,p1y = p2x,p2y

return inside

# Source shapefile

r = shapefile.Reader("GIS_CensusTract_poly.shp")

# pixel to coordinate info

xdist = r.bbox[2] - r.bbox[0]

ydist = r.bbox[3] - r.bbox[1]

iwidth = 600

iheight = 500

xratio = iwidth/xdist

yratio = iheight/ydist

c = pngcanvas.PNGCanvas(iwidth,iheight,color=[255,255,255,0xff])

# background color

c.filledRectangle(0,0,iwidth,iheight)

# Pen color

c.color = [139,137,137,0xff]

# Draw the polygons

for shape in r.shapes():

pixels = []

for x,y in shape.points:

px = int(iwidth - ((r.bbox[2] - x) * xratio))

py = int((r.bbox[3] - y) * yratio)

pixels.append([px,py])

c.polyline(pixels)

rnum = 0

trnum = len(r.shapeRecords())

for sr in r.shapeRecords():

rnum += 1

#print rnum, " of ", trnum

density = sr.record[20]

total = int(density / 50)

count = 0

minx, miny, maxx, maxy = sr.shape.bbox

while count < total:

x = random.uniform(minx,maxx)

y = random.uniform(miny,maxy)

if pip(x,y,sr.shape.points):

count += 1

#print " ", count, " of ", total

px = int(iwidth - ((r.bbox[2] - x) * xratio))

py = int((r.bbox[3] - y) * yratio)

c.point(px,py,color=[255,0,0,0xff])

f = file("density_pure.png", "wb")

f.write(c.dump())

f.close()

geospatialpython/DensityProfiler_pure.py at master · GeospatialPython/geospatialpython · GitHub

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