def get_osm_network(geodataframe, maxdist=5000, quiet=True, **kwargs):
"""Download a street network from OSM.
Parameters
----------
geodataframe : geopandas.GeoDataFrame
geopandas.GeoDataFrame of the study area.
Coordinate system should be in WGS84
maxdist : int
Total distance (in meters) of the network queries you may need.
This is used to buffer the network to ensure theres enough to satisfy
your largest query, otherwise there may be edge effects.
quiet: bool
If True, diagnostic messages from urbanaccess will be suppressed
**kwargs : dict
additional kwargs passed through to
urbanaccess.ua_network_from_bbox
Returns
-------
pandana.Network
A pandana Network instance for use in accessibility calculations or
spatial segregation measures that include a distance decay
"""
try:
import pandana as pdna
from urbanaccess.osm.load import ua_network_from_bbox
except ImportError:
raise ImportError(
"You need pandana and urbanaccess to work with segregation's network module\n"
"You can install them with `pip install urbanaccess pandana` "
"or `conda install -c udst pandana urbanaccess`")
gdf = geodataframe.copy()
gdf = gdf.to_crs(gdf.estimate_utm_crs())
gdf = gdf.buffer(maxdist)
bounds = gdf.to_crs(epsg=4326).total_bounds
if quiet:
print('Downloading data from OSM. This may take awhile.')
with _HiddenPrints():
net = ua_network_from_bbox(bounds[1], bounds[0], bounds[3],
bounds[2], **kwargs)
else:
net = ua_network_from_bbox(bounds[1], bounds[0], bounds[3], bounds[2],
**kwargs)
print("Building network")
network = pdna.Network(net[0]["x"], net[0]["y"], net[1]["from"],
net[1]["to"], net[1][["distance"]])
return network
def get_network(geodataframe, maxdist=5000, quiet=True, **kwargs):
"""Download a street network from OSM.
Parameters
----------
geodataframe : geopandas.GeoDataFrame
geopandas.GeoDataFrame of the study area.
maxdist : int
Total distance (in meters) of the network queries you may need.
This is used to buffer the network to ensure theres enough to satisfy
your largest query, otherwise there may be edge effects.
**kwargs : dict
additional kwargs passed through to
urbanaccess.ua_network_from_bbox
Returns
-------
pandana.Network
A pandana Network instance for use in accessibility calculations or
spatial segregation measures that include a distance decay
Examples
-------
Examples should be written in doctest format, and
should illustrate how to use the function/class.
>>>
"""
gdf = geodataframe.copy()
assert gdf.crs == {
'init': 'epsg:4326'
}, "geodataframe must be in epsg 4326"
gdf = project_gdf(gdf)
gdf = gdf.buffer(maxdist)
bounds = gdf.to_crs(epsg=4326).total_bounds
if quiet:
print('Downloading data from OSM. This may take awhile.')
with _HiddenPrints():
net = ua_network_from_bbox(bounds[1], bounds[0], bounds[3],
bounds[2], **kwargs)
else:
net = ua_network_from_bbox(bounds[1], bounds[0], bounds[3], bounds[2],
**kwargs)
print("Building network")
network = pdna.Network(net[0]["x"], net[0]["y"], net[1]["from"],
net[1]["to"], net[1][["distance"]])
return network
def test_column_names(bbox1):
nodes, edges = ua_network_from_bbox(bbox=bbox1,
network_type='walk',
timeout=180,
memory=None,
max_query_area_size=50 * 1000 * 50 *
1000,
remove_lcn=False)
col_list = ['x', 'y', 'id']
for col in col_list:
assert col in nodes.columns
col_list = ['distance', 'from', 'to']
for col in col_list:
assert col in edges.columns
def get_osm_network(geodataframe, maxdist=5000, quiet=True, output_crs=None, **kwargs):
"""Download a street network from OSM.
Parameters
----------
geodataframe : geopandas.GeoDataFrame
geopandas.GeoDataFrame of the study area.
Coordinate system should be in WGS84
maxdist : int
Maximum distance of the network queries you may need (this is used to buffer the
network to ensure there's enough to satisfy your largest query, otherwise there
may be edge effects. Distance is measured in the units of the geodataframe CRS. If
the CRS is geographic, a UTM approximation is used, so the units are meters.
quiet: bool
If True, diagnostic messages from urbanaccess will be suppressed
**kwargs : dict
additional kwargs passed through to
urbanaccess.ua_network_from_bbox
Returns
-------
pandana.Network
A pandana Network instance for use in accessibility calculations or
spatial segregation measures that include a distance decay
"""
assert geodataframe.crs, "The input geodataframe must have a valid CRS set"
if not output_crs:
output_crs = geodataframe.crs
try:
import pandana as pdna
from urbanaccess.osm.load import ua_network_from_bbox
except ImportError:
raise ImportError(
"You need pandana and urbanaccess to work with segregation's network module\n"
"You can install them with `pip install urbanaccess pandana` "
"or `conda install -c udst pandana urbanaccess`"
)
gdf = geodataframe.copy()
# Need coordinates in 4326 to request from OSM, but need projected for measuring distance
if geodataframe.crs.is_geographic:
# this is lazy because UTM can be inaccurate in some places on the earth, but generally works fine
warn(
"The geodataframe passed into the function is stored in a geographic CRS."
"Estimating maximum distance threshold using a UTM transformation"
)
gdf = gdf.to_crs(gdf.estimate_utm_crs())
gdf = gdf.buffer(maxdist)
bounds = gdf.to_crs(epsg=4326).total_bounds
else:
bounds = gdf.total_bounds
nodes, edges = ua_network_from_bbox(
bounds[1], bounds[0], bounds[3], bounds[2], **kwargs
)
nodes = _reproject_osm_nodes(nodes, 4326, output_crs)
network = pdna.Network(
nodes["x"], nodes["y"], edges["from"], edges["to"], edges[["distance"]]
)
return network
