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Merge pull request #506 from gboeing/feature
new geocoding module
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,161 @@ | ||
| """Geocode queries and create GeoDataFrames of place boundaries.""" | ||
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| import logging as lg | ||
| from collections import OrderedDict | ||
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| import geopandas as gpd | ||
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| from . import downloader | ||
| from . import projection | ||
| from . import settings | ||
| from . import utils | ||
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| def geocode(query): | ||
| """ | ||
| Geocode a query string to (lat, lng) with the Nominatim geocoder. | ||
| Parameters | ||
| ---------- | ||
| query : string | ||
| the query string to geocode | ||
| Returns | ||
| ------- | ||
| point : tuple | ||
| the (lat, lng) coordinates returned by the geocoder | ||
| """ | ||
| # define the parameters | ||
| params = OrderedDict() | ||
| params["format"] = "json" | ||
| params["limit"] = 1 | ||
| params[ | ||
| "dedupe" | ||
| ] = 0 # prevent OSM from deduping results so we get precisely 'limit' # of results | ||
| params["q"] = query | ||
| response_json = downloader.nominatim_request(params=params) | ||
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| # if results were returned, parse lat and long out of the result | ||
| if len(response_json) > 0 and "lat" in response_json[0] and "lon" in response_json[0]: | ||
| lat = float(response_json[0]["lat"]) | ||
| lng = float(response_json[0]["lon"]) | ||
| point = (lat, lng) | ||
| utils.log(f'Geocoded "{query}" to {point}') | ||
| return point | ||
| else: | ||
| raise Exception(f'Nominatim geocoder returned no results for query "{query}"') | ||
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| def geocode_to_gdf(query, which_result=1, buffer_dist=None): | ||
| """ | ||
| Geocode a query or queries to a GeoDataFrame with the Nominatim geocoder. | ||
| Geometry column contains place boundaries if they exist in OpenStreetMap. | ||
| Query can be a string or dict, or a list of strings/dicts to send to the | ||
| geocoder. If query is a list, then which_result should be a list of the | ||
| same length. | ||
| Parameters | ||
| ---------- | ||
| query : string or dict or list | ||
| query string or structured dict to geocode/download | ||
| which_result : int or list | ||
| max number of results to return and which to process upon receipt; if | ||
| passing a list then it must be same length as query | ||
| buffer_dist : float | ||
| distance to buffer around the place geometry, in meters | ||
| Returns | ||
| ------- | ||
| gdf : geopandas.GeoDataFrame | ||
| """ | ||
| # if caller passed a list of queries but a scalar which_result value, then | ||
| # turn which_result into a list with same length as query list | ||
| if isinstance(query, list) and isinstance(which_result, int): | ||
| which_result = [which_result] * len(query) | ||
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| # turn query and which_result into lists if they're not already | ||
| if not isinstance(query, list): | ||
| query = [query] | ||
| if not isinstance(which_result, list): | ||
| which_result = [which_result] | ||
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| # ensure same length | ||
| if len(query) != len(which_result): | ||
| raise ValueError("which_result length must equal query length") | ||
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| # ensure query type | ||
| for q in query: | ||
| if not isinstance(q, (str, dict)): | ||
| raise ValueError("each query must be a dict or a string") | ||
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| # geocode each query and add to GeoDataFrame as a new row | ||
| gdf = gpd.GeoDataFrame() | ||
| for q, wr in zip(query, which_result): | ||
| gdf_tmp = _geocode_query_to_gdf(q, wr) | ||
| gdf = gdf.append(gdf_tmp) | ||
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| # reset GeoDataFrame index and set its CRS | ||
| gdf = gdf.reset_index(drop=True) | ||
| gdf.crs = settings.default_crs | ||
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| # if buffer_dist was passed in, project the geometry to UTM, buffer it in | ||
| # meters, then project it back to lat-lng | ||
| if buffer_dist is not None and len(gdf) > 0: | ||
| gdf_utm = projection.project_gdf(gdf) | ||
| gdf_utm["geometry"] = gdf_utm["geometry"].buffer(buffer_dist) | ||
| gdf = projection.project_gdf(gdf_utm, to_latlong=True) | ||
| utils.log(f"Buffered GeoDataFrame to {buffer_dist} meters") | ||
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| utils.log(f"Created GeoDataFrame with {len(gdf)} rows from {len(query)} queries") | ||
| return gdf | ||
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| def _geocode_query_to_gdf(query, which_result=1): | ||
| """ | ||
| Geocode a single place query to a GeoDataFrame. | ||
| Parameters | ||
| ---------- | ||
| query : string or dict | ||
| query string or structured dict to geocode/download | ||
| which_result : int | ||
| max number of results to return and which to process upon receipt | ||
| Returns | ||
| ------- | ||
| gdf : geopandas.GeoDataFrame | ||
| """ | ||
| data = downloader._osm_polygon_download(query, limit=which_result) | ||
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| if len(data) >= which_result: | ||
| # extract data elements from the JSON response | ||
| result = data[which_result - 1] | ||
| bbox_south, bbox_north, bbox_west, bbox_east = [float(x) for x in result["boundingbox"]] | ||
| geometry = result["geojson"] | ||
| place = result["display_name"] | ||
| features = [ | ||
| { | ||
| "type": "Feature", | ||
| "geometry": geometry, | ||
| "properties": { | ||
| "place_name": place, | ||
| "bbox_north": bbox_north, | ||
| "bbox_south": bbox_south, | ||
| "bbox_east": bbox_east, | ||
| "bbox_west": bbox_west, | ||
| }, | ||
| } | ||
| ] | ||
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| # if we got an unexpected geometry type (like a point), log a warning | ||
| if geometry["type"] not in ["Polygon", "MultiPolygon"]: | ||
| utils.log(f'OSM returned a {geometry["type"]} as the geometry', level=lg.WARNING) | ||
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| # create the GeoDataFrame | ||
| return gpd.GeoDataFrame.from_features(features) | ||
| else: | ||
| # if no data returned (or fewer results than which_result) | ||
| msg = f'OSM returned no results (or fewer than which_result) for query "{query}"' | ||
| utils.log(msg, level=lg.WARNING) | ||
| return gpd.GeoDataFrame() |
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