Qiita Teams that are logged in
You are not logged in to any team

Log in to Qiita Team
OrganizationAdvent CalendarQiitadon (β)
Qiita JobsQiita ZineQiita Blog
Help us understand the problem. What is going on with this article?

OSM データを NetworkX へ取り込んで最短経路計算

OSMParser.py (import open street map data as a networkx graph)1 2 というものを見つけたので、少し手を加えて動かしてみました。NetworkX へ OSM データ(シアトル市)を取り込み(車道や歩道の区別なし)、指定2点間3の最短経路を求めました(赤線)。

スクリーンショット 2018-01-11 22.00.41.jpg

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

Read directional graph from Open Street Maps osm format

Based on Loïc Messal's OSMParser.py: https://gist.github.com/Tofull/49fbb9f3661e376d2fe08c2e9d64320e
Use python3.6


import math
import copy
import networkx # 2.0
import xml.sax # parse osm file
from pathlib import Path # manage cached tiles

RE = 6378137.0  # GRS80
FE = 1/298.257223563  # IS-GPS
E2 = FE * (2 - FE)
DEGREE = math.pi / 180

def distance(u, v):
    p, q = u['pos'], v['pos']
    coslat = math.cos((p[1]+q[1])/2*DEGREE)
    w2 = 1 / (1 - E2 * (1 - coslat * coslat))
    dx = (p[0]-q[0]) * coslat
    dy = (p[1]-q[1]) * w2 * (1 - E2)
    return math.sqrt((dx*dx+dy*dy)*w2) * DEGREE * RE

def download_osm(left, bottom, right, top, proxy = False, proxyHost = "", proxyPort = "3128", cache = False, cacheTempDir = "/tmp/tmpOSM/", verbose = True):
    """ Return a filehandle to the downloaded data from osm api."""

    import urllib.request # To request the web

    if (cache):
        ## cached tile filename
        cachedTileFilename = "osm_map_{:.8f}_{:.8f}_{:.8f}_{:.8f}.map".format(left, bottom, right, top)

        if (verbose):
            print("Cached tile filename :", cachedTileFilename)

        Path(cacheTempDir).mkdir(parents = True, exist_ok = True) ## Create cache path if not exists

        osmFile = Path(cacheTempDir + cachedTileFilename).resolve() ## Replace the relative cache folder path to absolute path

        if osmFile.is_file():
            # download from the cache folder
            if (verbose):
                print("Tile loaded from the cache folder.")

            fp = urllib.request.urlopen("file://"+str(osmFile))
            return fp

    if (proxy):
        # configure the urllib request with the proxy
        proxy_handler = urllib.request.ProxyHandler({'https': 'https://' + proxyHost + ":" + proxyPort, 'http': 'http://' + proxyHost + ":" + proxyPort})
        opener = urllib.request.build_opener(proxy_handler)

    request = "http://api.openstreetmap.org/api/0.6/map?bbox=%f,%f,%f,%f"%(left,bottom,right,top)

    if (verbose):
        print("Download the tile from osm web api ... in progress")
        print("Request :", request)

    fp = urllib.request.urlopen(request)

    if (cache):
        if (verbose):
            print("Write osm tile in the cache")
        content = fp.read()
        with open(osmFile, 'wb') as f:

        if osmFile.is_file():
            if (verbose):
                print("OSM tile written in the cache")

            fp = urllib.request.urlopen("file://"+str(osmFile)) ## Reload the osm tile from the cache (because fp.read moved the cursor)
            return fp

    return fp

def read_osm(filename_or_stream, only_roads=True):
    """Read graph in OSM format from file specified by name or by stream object.
    filename_or_stream : filename or stream object

    G : Graph
    osm = OSM(filename_or_stream)
    G = networkx.DiGraph()

    ## Add ways
    for w in osm.ways.values():
        if only_roads and 'highway' not in w.tags:

        G.add_path(w.nds, id=w.id)
        # reverse direction
        if ('oneway' not in w.tags) or (w.tags['oneway'] != 'yes'):
            G.add_path(w.nds[::-1], id=w.id)

    ## Complete the used nodes' information
    for n_id in list(G.nodes):
        n = osm.nodes[n_id]
        G.nodes[n_id]['pos'] = [n.lon, n.lat]

    ## Estimate the length of each way
    for u,v in G.edges():
        d = distance(G.nodes[u], G.nodes[v])
        G.add_weighted_edges_from([(u, v, d)], weight='length')
    return G

class Node:
    def __init__(self, id, lon, lat):
        self.id = id
        self.lon = lon
        self.lat = lat
        self.tags = {}

    def __str__(self):
        return "Node (id : %s) lon : %s, lat : %s "%(self.id, self.lon, self.lat)

class Way:
    def __init__(self, id, osm):
        self.osm = osm
        self.id = id
        self.nds = []
        self.tags = {}

    def split(self, dividers):
        # slice the node-array using this nifty recursive function
        def slice_array(ar, dividers):
            for i in range(1,len(ar)-1):
                if dividers[ar[i]]>1:
                    left = ar[:i+1]
                    right = ar[i:]
                    rightsliced = slice_array(right, dividers)
                    return [left]+rightsliced
            return [ar]

        slices = slice_array(self.nds, dividers)

        # create a way object for each node-array slice
        ret = []
        for slice in slices:
            littleway = copy.copy( self )
            littleway.id += "-%d"%i
            littleway.nds = slice
            ret.append( littleway )
            i += 1
        return ret

class OSM:
    def __init__(self, filename_or_stream):
        """ File can be either a filename or stream/file object."""
        nodes = {}
        ways = {}

        superself = self

        class OSMHandler(xml.sax.ContentHandler):
            def setDocumentLocator(self,loc):

            def startDocument(self):

            def endDocument(self):

            def startElement(self, name, attrs):
                if name=='node':
                    self.currElem = Node(attrs['id'], float(attrs['lon']), float(attrs['lat']))
                elif name=='way':
                    self.currElem = Way(attrs['id'], superself)
                elif name=='tag':
                    self.currElem.tags[attrs['k']] = attrs['v']
                elif name=='nd':
                    self.currElem.nds.append( attrs['ref'] )

            def endElement(self,name):
                if name=='node':
                    nodes[self.currElem.id] = self.currElem
                elif name=='way':
                    ways[self.currElem.id] = self.currElem

            def characters(self, chars):

        xml.sax.parse(filename_or_stream, OSMHandler)
        self.nodes = nodes
        self.ways = ways
        #count times each node is used
        node_histogram = dict.fromkeys( self.nodes.keys(), 0 )
        for way in self.ways.values():
            if len(way.nds) < 2:       #if a way has only one node, delete it out of the osm collection
                del self.ways[way.id]
                for node in way.nds:
                    node_histogram[node] += 1
        #use that histogram to split all ways, replacing the member set of ways
        new_ways = {}
        for _, way in self.ways.items():
            split_ways = way.split(node_histogram)
            for split_way in split_ways:
                new_ways[split_way.id] = split_way
        self.ways = new_ways

def transpose_list(list2d):
    return map(list, zip(*list2d)) 

def center_pos(G):
    pos = [G.nodes[n]['pos'] for n in G]
    lons, lats = tuple(transpose_list(pos))
    return [(min(lons)+max(lons))/2, (min(lats)+max(lats))/2]

def plot_osm(G, path=None):
    import matplotlib.pyplot as plt
    coslat = math.cos(center_pos(G)[1]*DEGREE)
    ax = plt.figure().add_subplot(111)
    if path:
        ax.plot(*path, color='red', lw=1.6)
    for u, v in G.edges():
        e = transpose_list([G.nodes[u]['pos'], G.nodes[v]['pos']])
        ax.plot(*e, color='0.6', lw=0.5)
    ns = transpose_list([G.nodes[n]['pos'] for n in G])
    ax.plot(*ns, 'o', color='black', mec='none', ms=1.2)

def main():
    f = download_osm(-122.331,47.599,-122.315,47.609) # Seattle
    G = read_osm(f)
    source, target = '3872031394', '3669099186'
    dist = lambda u,v: distance(G.nodes[u],G.nodes[v])
    path = networkx.astar_path(G, source, target, heuristic=dist, weight='length')
    path = transpose_list([G.nodes[u]['pos'] for u in path])
    plot_osm(G, path)

if __name__ == '__main__':

  1. これと似たものとして、osm2nxosmnxosmgraph があるようです。 

  2. なお xml 形式ではなく pbf 形式ファイルの読み込みには、 imposm.parser(Python 2.x 専用)、osmreadpyosmium があるようです。 

  3. openstreetmap 内の query mode ツール(地物を検索)で、ノード ID (source, target) を確認することができます(簡単とは言えませんが)。 

Help us understand the problem. What is going on with this article?
Why not register and get more from Qiita?
  1. We will deliver articles that match you
    By following users and tags, you can catch up information on technical fields that you are interested in as a whole
  2. you can read useful information later efficiently
    By "stocking" the articles you like, you can search right away


No comments
Sign up for free and join this conversation.
Sign Up
If you already have a Qiita account Login
Help us understand the problem. What is going on with this article?