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New function for calculating great circle distance
Calculated using the Haversine formula. I also removed some of the existing functions in pandana.utils that depended on GeoPandas and other geo libraries.
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import numpy.testing as npt | ||
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from pandana.utils import great_circle_dist as gcd | ||
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def test_gcd(): | ||
# tested against geopy | ||
# https://geopy.readthedocs.org/en/latest/#module-geopy.distance | ||
lat1 = 41.49008 | ||
lon1 = -71.312796 | ||
lat2 = 41.499498 | ||
lon2 = -81.695391 | ||
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expected = 864456.76162966 | ||
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npt.assert_allclose(gcd(lat1, lon1, lat2, lon2), expected) |
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from shapely.geometry import Point | ||
from fiona import crs | ||
import geopandas as gpd | ||
import pandas as pd | ||
import numpy as np | ||
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def bbox_convert(bbox, from_epsg, to_epsg): | ||
bbox = gpd.GeoSeries([Point(bbox[0], bbox[1]), | ||
Point(bbox[2], bbox[3])], | ||
crs=crs.from_epsg(from_epsg)) | ||
bbox = bbox.to_crs(epsg=to_epsg) | ||
bbox = [bbox[0].x, bbox[0].y, bbox[1].x, bbox[1].y] | ||
return bbox | ||
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def get_nodes_from_osm(bbox, query, to_epsg=3740): | ||
gdf = gpd.io.osm.query_osm('node', | ||
bbox=bbox, | ||
tags=query) | ||
gdf = gdf[gdf.type == 'Point'].to_crs(epsg=to_epsg) | ||
print "Found %d nodes" % len(gdf) | ||
x, y = zip(*[(p.x, p.y) for (i, p) | ||
in gdf.geometry.iteritems()]) | ||
x = pd.Series(x) | ||
y = pd.Series(y) | ||
return x, y | ||
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def anything_score(net, config, max_distance, decay, bbox): | ||
score = pd.Series(np.zeros(len(net.node_ids)), index=net.node_ids) | ||
for query, weights in config.iteritems(): | ||
print "Computing for query: %s" % query | ||
print "Fetching nodes from OSM" | ||
x, y = get_nodes_from_osm(bbox, query) | ||
print "Done" | ||
net.set_pois(query, x, y) | ||
print "Computing nearest" | ||
df = net.nearest_pois(max_distance, query, num_pois=len(weights)) | ||
print "Done" | ||
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for idx, weight in enumerate(weights): | ||
# want the 1st not the 0th | ||
idx += 1 | ||
print "Adding contribution %f for number %d nearest" % \ | ||
(weight, idx) | ||
score += decay(df[idx])*weight | ||
# print score.describe() | ||
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assert score.min() > 0 | ||
return score/score.max()*100 | ||
from __future__ import division | ||
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import math | ||
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def great_circle_dist(lat1, lon1, lat2, lon2): | ||
""" | ||
Get the distance (in meters) between two lat/lon points | ||
via the Haversine formula. | ||
Parameters | ||
---------- | ||
lat1, lon1, lat2, lon2 : float | ||
Latitude and longitude in degrees. | ||
Returns | ||
------- | ||
dist : float | ||
Distance in meters. | ||
""" | ||
radius = 6372795 # meters | ||
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lat1 = math.radians(lat1) | ||
lon1 = math.radians(lon1) | ||
lat2 = math.radians(lat2) | ||
lon2 = math.radians(lon2) | ||
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dlat = lat2 - lat1 | ||
dlon = lon2 - lon1 | ||
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# formula from: | ||
# http://en.wikipedia.org/wiki/Haversine_formula#The_haversine_formula | ||
a = math.pow(math.sin(dlat / 2), 2) | ||
b = math.cos(lat1) * math.cos(lat2) * math.pow(math.sin(dlon / 2), 2) | ||
d = 2 * radius * math.asin(math.sqrt(a + b)) | ||
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return d |