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I have two lists of points (latitudes, longitudes) - locations & events:

locations = [[54.156014, 53.017209], [2.74284, 103.68141], [3.133688, 102.688424], [24.499918, 55.388891], [21.488382, 61.395062], [24.479778, 59.354986], [25.180161, 78.269545], [-31.5796783, -58.5812265]]
events = [[-15.794157,  -47.882529],[33.319392, 44.347046],[26.225653, 50.535556],[50.447336, 30.536875],[50.447336, 30.536875],[50.442721, 30.52179],[50.442721, 30.52179],[-15.794157, -47.882529],[3.848032, 11.502075],[-12.97304, -38.502304],[26.226559, 50.54591],[-34.603684, -58.381559],[32.094771, 20.187911],[48.868472, 2.330211],[-30.032056, -51.208428],[32.887209, 13.191338],[13.767966, 100.534526],[-34.92849, 138.60074],[32.887209, 13.191338],[26.230536, 50.527792],[50.4501, 30.5234],[50.4501, 30.5234],[50.442721, 30.52179],[50.442721, 30.52179],[50.447137, 30.537357],[50.447137, 30.537357],[12.81063, 45.035019],[26.225653, 50.535556],[-12.97304, -38.502304],[26.226559, 50.54591],[35.675888, 139.744858],
[12.813674, 45.034161],[54.156014, 53.017210]]

I would like to check which of the events occurred in the 2 kilometer radius buffer from locations.

If one event occurred in multiple buffers I would like to have this event attached to multiple locations that it occurred in the nearby.

What I have tried: I have converted locations list and events list to dataframes and did following:

locations_gpd = gpd.GeoDataFrame(locations, geometry=gpd.points_from_xy(locations.longitude, locations.lattitude).buffer(2, 16), crs = {'init':'epsg:4326'})

events_gpd = gpd.GeoDataFrame(events, geometry=gpd.points_from_xy(events.longitude, events.latitude), crs = {'init':'epsg:4326'})


intersection = gpd.sjoin(locations_gpd, events_gpd, how='left')

This actually performs the intersection well, but the buffer zone is bigger than 2km (I plotted the results and can see on the map) I cant figure out how to apply correct distance/resolution parameters (2km) in GeoDataFrame.buffer(distance, resolution)

PS. I am beginner with GeoPandas, could you give me a lead how to perform this intersection?

M.wol
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    What have you tried because unless you add a Python code attempt your question will be closed – gene Dec 10 '20 at 12:31
  • https://gis.stackexchange.com/questions/253224/geopandas-buffer-using-geodataframe-while-maintaining-the-dataframe/253387 – Yogesh Chavan Dec 10 '20 at 14:11

1 Answers1

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I think the issue is that you buffer the locations while using the EPSG 4326 projection. This doesn't use meters as the unit so the buffer zones will not all be 2km.

Here I re-project the data to the WGS 84 / Pseudo-Mercator projection. Depending on where your points are located there might be a more suitable projection.

locations = [[54.156014, 53.017209], [2.74284, 103.68141], [3.133688, 102.688424], [24.499918, 55.388891], [21.488382, 61.395062], [24.479778, 59.354986], [25.180161, 78.269545], [-31.5796783, -58.5812265]]

events = [[-15.794157,  -47.882529],[33.319392, 44.347046],[26.225653, 50.535556],[50.447336, 30.536875],[50.447336, 30.536875],[50.442721, 30.52179],[50.442721, 30.52179],[-15.794157, -47.882529],[3.848032, 11.502075],[-12.97304, -38.502304],[26.226559, 50.54591],[-34.603684, -58.381559],[32.094771, 20.187911],[48.868472, 2.330211],[-30.032056, -51.208428],[32.887209, 13.191338],[13.767966, 100.534526],[-34.92849, 138.60074],[32.887209, 13.191338],[26.230536, 50.527792],[50.4501, 30.5234],[50.4501, 30.5234],[50.442721, 30.52179],[50.442721, 30.52179],[50.447137, 30.537357],[50.447137, 30.537357],[12.81063, 45.035019],[26.225653, 50.535556],[-12.97304, -38.502304],[26.226559, 50.54591],[35.675888, 139.744858],[12.813674, 45.034161],[54.156014, 53.017210]]


dfLocations = pd.DataFrame(columns = ['longitude', 'latitude'], data = locations)
dfEvents = pd.DataFrame(columns = ['longitude', 'longitude'] , data = events)
gdfLocations = gpd.GeoDataFrame(dfLocations, geometry=gpd.points_from_xy(dfLocations.longitude, dfLocations.latitude), crs = {'init':'epsg:4326'})
gdfEvents = gpd.GeoDataFrame(dfEvents, geometry=gpd.points_from_xy(dfEvents.longitude, dfEvents.latitude), crs = {'init':'epsg:4326'})


Now reproject to a crs using meters


gdfLocations = gdfLocations.to_crs({'init':'epsg:3857'})
gdfEvents = gdfEvents.to_crs({'init':'epsg:3857'})


Buffer and join


gdfLocations['geometry'] = gdfLocations['geometry'].buffer(2000)
intersection = gpd.sjoin(gdfLocations, gdfEvents, how='left')
Obi
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