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pythonjoinspatialgeopandasshapely
Gulzar Ahmed
Gulzar Ahmed

Reputation: 1

Trying to understand the max_distance parameter in Spatial Join sjoin_nearest() GeoPandas Python

I have two geopandas dataframe having Point and LineString Geometries.

I want to use spatial joins to combine these dataframes on the basis of the distance between them.

Following are the two geometrical columns I want to use for joining:

[Point Geometry] (https://i.sstatic.net/hPkQw.png)

[LineString] (https://i.sstatic.net/uIWs6.png)

I used sjoin_nearest() function in geopandas to join based on their distance. Following is the line of code I am using for joining:

joined_df = point_gdf.sjoin_nearest(gdf,how='left',distance_col='distances',max_distance=0.06219)

Someone told me that the unit of max_distance is miles so I tried converting 100 meters to miles and then providing the value.

I get the following output:

[Joined Dataframe] (https://i.sstatic.net/pAi6K.png)

Now I am confused about the max_distance parameter in sjoin_nearest().

Upvotes: 0

Views: 303

Answers (1)

Bera
Bera

Reputation: 1949

The distance is in the units of the coordinate system you are using.

By the coordinates it looks like EPSG:4326 which have

Unit: degree (supplier to define representation)

You should not be measuring distances in degrees. 1 degree near the equator will be very different from 1 degree nearer the poles.

Reproject your data into a projected coordinate system with units in for example meters. Like one of the UTM zones.

If your data is in Saudi Arabia you can use EPSG:9357

Upvotes: 0

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