osm support

evrouting/osm.py

+"""
+Convert a Open Street Maps `.map` format file into a networkx directional graph.
+
+This parser is based on the osm to networkx tool from aflaxman : https://gist.github.com/aflaxman/287370/
+
+
+Added :
+- python3.6 compatibility
+- networkx v2 compatibility
+- cache to avoid downloading the same osm tiles again and again
+- distance computation to estimate length of each ways (useful to compute the shortest path)
+
+Copyright (C) 2017 Loïc Messal (github : Tofull)
+
+"""
+
+import copy
+import urllib.request
+import xml.sax
+from math import radians, cos, sin, asin, sqrt
+from pathlib import Path
+
+import networkx
+
+
+def haversine_distance(lon1, lat1, lon2, lat2, unit_m=True):
+    """
+    Calculate the great circle distance between two points
+    on the earth (specified in decimal degrees)
+    default unit : km
+    """
+    # convert decimal degrees to radians
+    lon1, lat1, lon2, lat2 = map(radians, [lon1, lat1, lon2, lat2])
+
+    # haversine formula
+    dlon = lon2 - lon1
+    dlat = lat2 - lat1
+    a = sin(dlat / 2)**2 + cos(lat1) * cos(lat2) * sin(dlon / 2)**2
+    c = 2 * asin(sqrt(a))
+    r = 6371  # Radius of the Earth in kilometers. Use 3956 for miles
+    if unit_m:
+        r *= 1000
+    return c * r
+
+
+def download_osm(left=-73.4244, bottom=45.4302, right=-73.4010, top=45.4466, proxy=False, proxyHost="10.0.4.2", proxyPort="3128", cache=False, cacheTempDir="/tmp/tmpOSM/", verbose=True):
+    """ Return a filehandle to the downloaded data from osm api."""
+    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)
+
+        cacheTempDir = Path(cacheTempDir)
+        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.")
+
+            with open(osmFile, mode='r') as f:
+                content = f.read()
+            return content
+
+    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)
+        urllib.request.install_opener(opener)
+
+    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)
+    content = fp.read().decode('utf-8')
+
+    if verbose:
+        print("OSM Tile downloaded")
+
+    if cache:
+        if verbose:
+            print("Write osm tile in the cache")
+
+        with open(osmFile, 'w') as f:
+            f.write(content)
+
+        if osmFile.is_file():
+            if verbose:
+                print("OSM tile written in the cache")
+
+    return content
+
+
+def read_osm(osm_xml_data, is_xml_string=True, only_roads=True):
+    """Read graph in OSM format from file specified by name or by stream object.
+    Parameters
+    ----------
+    filename_or_stream : filename or stream object
+
+    Returns
+    -------
+    G : Graph
+
+    Examples
+    --------
+    >>> G=nx.read_osm(nx.download_osm(-122.33,47.60,-122.31,47.61))
+    >>> import matplotlib.pyplot as plt
+    >>> plt.plot([G.node[n]['lat']for n in G], [G.node[n]['lon'] for n in G], 'o', color='k')
+    >>> plt.show()
+    """
+    osm = OSM(osm_xml_data, is_xml_string=is_xml_string)
+    G = networkx.DiGraph()
+
+    ## Add ways
+    for w in osm.ways.values():
+        if only_roads and 'highway' not in w.tags:
+            continue
+
+        if ('oneway' in w.tags):
+            if (w.tags['oneway'] == 'yes'):
+                # ONLY ONE DIRECTION
+                networkx.add_path(G, w.nds, id=w.id)
+            else:
+                # BOTH DIRECTION
+                networkx.add_path(G, w.nds, id=w.id)
+                networkx.add_path(G, w.nds[::-1], id=w.id)
+        else:
+            # BOTH DIRECTION
+            networkx.add_path(G, w.nds, id=w.id)
+            networkx.add_path(G, w.nds[::-1], id=w.id)
+
+    # Complete the used nodes' information
+    coordinates_map = {}
+    for n_id in G.nodes():
+        n = osm.nodes[n_id]
+        G.nodes[n_id]['lat'] = n.lat
+        G.nodes[n_id]['lon'] = n.lon
+        G.nodes[n_id]['id'] = n.id
+        coordinates_map[n_id] = (n.lon, n.lat)
+
+    # Estimate the length of each way
+    for u, v, d in G.edges(data=True):
+        distance = haversine_distance(G.nodes[u]['lon'], G.nodes[u]['lat'], G.nodes[v]['lon'], G.nodes[v]['lat'], unit_m=True)  # Give a realistic distance estimation (neither EPSG nor projection nor reference system are specified)
+
+        G.add_weighted_edges_from([(u, v, distance)], weight='havlen')
+
+    G = networkx.relabel_nodes(G, coordinates_map)
+    return G
+
+
+class Node(object):
+    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(object):
+    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 = []
+        i = 0
+        for slice in slices:
+            littleway = copy.copy(self)
+            littleway.id += "-%d" % i
+            littleway.nds = slice
+            ret.append(littleway)
+            i += 1
+
+        return ret
+
+
+class OSM(object):
+    def __init__(self, osm_xml_data, is_xml_string=True):
+        """ File can be either a filename or stream/file object.
+
+        set `is_xml_string=False` if osm_xml_data is a filename or a file stream.
+        """
+        nodes = {}
+        ways = {}
+
+        superself = self
+
+        class OSMHandler(xml.sax.ContentHandler):
+            @classmethod
+            def setDocumentLocator(self, loc):
+                pass
+
+            @classmethod
+            def startDocument(self):
+                pass
+
+            @classmethod
+            def endDocument(self):
+                pass
+
+            @classmethod
+            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'])
+
+            @classmethod
+            def endElement(self, name):
+                if name == 'node':
+                    nodes[self.currElem.id] = self.currElem
+                elif name == 'way':
+                    ways[self.currElem.id] = self.currElem
+
+            @classmethod
+            def characters(self, chars):
+                pass
+
+        if is_xml_string:
+            xml.sax.parse(osm_xml_data, OSMHandler)
+        else:
+            with open(osm_xml_data, mode='r') as f:
+                xml.sax.parse(f, 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]
+            else:
+                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 id, 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