compute_regions.py

#!/usr/bin/env python3
import sys, json
from misc import *
from geometry import *
from configparser import ConfigParser

class Blockmap:
	'''
	The blockmap is a grid of latitude and longitude lines and models
	a block -> set relation. A block is a latitude and longitude square.
	'''
	block_size = 200.0 # How big are blocks?
	def __init__(self, blocks = None):
		from collections import defaultdict
		self.blocks = blocks or defaultdict(set)
	def __getitem__(self, blockid):
		'''
		Returns a block for block coordinates. The block is a set that can
		contain anything.
		'''
		return self.blocks[blockid]
	def blockpoint(self, point):
		'''
		Returns blockmap coordinates for geographical coordinates.
		The blockmap coordinates refer to a block in the blockmap.
		'''
		block_coordinate = lambda x: int(x * self.block_size)
		return block_coordinate(point.x), block_coordinate(point.y)

def blocks_in_shape(blockmap, shape):
	'''
	Finds all blocks inside the bounding box of a shape.
	'''
	from itertools import product
	min_x, max_x = minmax(point.x for point in shape.points)
	min_y, max_y = minmax(point.y for point in shape.points)
	min_blockpoint = blockmap.blockpoint(Location(min_x, min_y))
	max_blockpoint = blockmap.blockpoint(Location(max_x, max_y))
	range_x = range(min_blockpoint[0], max_blockpoint[0] + 1)
	range_y = range(min_blockpoint[1], max_blockpoint[1] + 1)
	yield from (blockmap[x, y] for x, y in product(range_x, range_y))

def create_blockmap(regions):
	'''
	Creates a blockmap of regions
	'''
	blockmap = Blockmap()
	for region in regions.values():
		# Minor shapes contain major shapes, so just use those
		for shape in (region['minor_shapes'] or region['major_shapes']):
			for block in blocks_in_shape(blockmap, shape):
				set.add(block, region['ref'])
	return blockmap

def get_args():
	from argparse import ArgumentParser
	parser = ArgumentParser()
	parser.add_argument('gtfs_zip')
	parser.add_argument('profile')
	return parser.parse_args()

def test_shapes(shapes, point):
	return any(shape.contains_point(point) for shape in shapes)

class RegionalLocation:
	def __init__(self, *, region, region_class):
		self.region, self.region_class = region, region_class
	def __repr__(self):
		return str.format(
			'RegionalLocation(region = {region}, region_class = {region_class})',
			region = repr(self.region),
			region_class = repr(self.region_class),
		)

def locate_regionally(position, region):
	if test_shapes(region['major_shapes'], position):
		return RegionalLocation(region = region['ref'], region_class = 'major')
	elif test_shapes(region['minor_shapes'], position):
		return RegionalLocation(region = region['ref'], region_class = 'minor')
	else:
		return None

def find_region_for_point(position, regions, blockmap):
	for region_name in blockmap[blockmap.blockpoint(position)]:
		region = regions[region_name]
		classification = locate_regionally(position, region)
		if classification:
			return classification

class RegionTester:
	def __init__(self, regions):
		self.regions = regions
		self.blockmap = create_blockmap(regions)
	def __call__(self, latitude, longitude):
		return find_region_for_point(
			position = Location(float(latitude), float(longitude)),
			regions = self.regions,
			blockmap = self.blockmap,
		)