topic Re: Points to Polylines using an SEDF in ArcGIS API for Python Questions

Points to Polylines using an SEDF

Webturtles — Mon, 22 Mar 2021 22:46:35 GMT

I have a SEDF populated from a CSV file (3-7 million rows):

sdfpositions = pd.DataFrame.spatial.from_xy(df=dfpositions, x_column = "LatDeg", y_column = "LongDeg",sr=4326)

and was looking to migrate a Geopandas points to polyline groupby process across to ESRI land.
GP version:

dflines = dfpositions.groupby(['Group_ID'], as_index=False)['geometry'].apply(lambda x: LineString(x.tolist()))

Would have hoped this might have worked:

sdflines = sdfpositions.groupby(['Group_ID'], as_index=False)['SHAPE'].apply(lambda x: LineString(x.tolist()))

It fails with:

 File "shapely\speedups\_speedups.pyx", line 88, in shapely.speedups._speedups.geos_linestring_from_py
AttributeError: 'list' object has no attribute '__array_interface__'

The fail I think is somewhere in the highlighted blue text.

Is this process possible in a SEDF? Really want to use it as the speed for save to FGDB is far better than GP to shapefile or geopackage (and I need to do other arcpy steps later on).

If not, wondering if worth trying to build the linestring JSON by injecting the point XY pairs and then converting to a polyline SEDF.

I have made the assumption that switching to Arcpy would slow things down, as you would have to save out, then run points to polylines save out again etc.

Re: Points to Polylines using an SEDF

simoxu — Wed, 24 Mar 2021 06:49:59 GMT

I can't see any problems in the workflow.

I guess it's in the lambda function constructing the geometry string for the new ploylines

Re: Points to Polylines using an SEDF

Webturtles — Wed, 24 Mar 2021 15:23:32 GMT

So do things have to called differently in the SEDF, or is there something more amiss?

Re: Points to Polylines using an SEDF

Webturtles — Wed, 24 Mar 2021 16:05:40 GMT

Whilst having a peruse of the documentation, I came across the from_geodataframe function! So if all else fails, I will just switch from a geodataframe to SEDF before saving out. Downside I guess is more overhead.

#load flat coords into points geodataframe
gdfpositions = gpd.GeoDataFrame(dfpositions, geometry = gpd.points_from_xy(df.LongDeg, df.LatDeg))
#Make lines from grouped points based on groupID
gdflines = gdfpositions.groupby(['Group_ID'], as_index=False)['geometry'].apply(lambda x: LineString(x.tolist()))
#convert line geodataframe into SEDF
sdflines = GeoAccessor.from_geodataframe(gdflines, inplace=False, column_name='SHAPE')

Re: Points to Polylines using an SEDF

simoxu — Wed, 24 Mar 2021 23:28:36 GMT

The error occurs when using LineString(), have to see the data that goes into it to diagnose.

Anyway, have you read the following help doc?

https://developers.arcgis.com/python/guide/part2-working-with-geometries/#Creating-Polyline-objects

It talks about the constructing geometry and the geometry engines behind the scenes (ArcPy or Shapely)

Hope it helps