topic Re: Split Polylines at certain increments in Python Questions

Split Polylines at certain increments

CCWeedcontrol — Wed, 06 Jan 2021 19:10:06 GMT

I need to create a polyline grid with vertical and horizontal lines of increments of one hundred, somehow divide each polyline/polygon by 9 and across multiple polygons/polylines and I am not sure on how go about doing it. What I have is the polygons/sections and polylines/sections lines.. The polygons/polylines are NOT evenly squared so I can't use fish net, at least I don't think...?

Re: Split Polylines at certain increments

DavidPike — Wed, 06 Jan 2021 19:46:06 GMT

Can you give some more context?

What's the purpose of this?

What are the blue lines, I'm guessing gridlines but what projection etc. and why are they not regular?

What is 'range'? I might think its the length and width of the blue squares, but then you say you need increments of 100, which throws me off. Also 100 what? Which ones are polygons and which are polylines?

Finally, what's the increase from right to left, and of what units?

Re: Split Polylines at certain increments

DanPatterson — Wed, 06 Jan 2021 19:53:15 GMT

Create Fishnet (Data Management)—ArcGIS Pro | Documentation

you can and could always specify the width and height of each rectangle... just specify a polyline output

Re: Split Polylines at certain increments

BlakeTerhune — Wed, 06 Jan 2021 20:47:10 GMT

I agree with @DanPatterson, it seems like you could use Fishnet with some combination of cell size, cell count, or extent.

Re: Split Polylines at certain increments

CCWeedcontrol — Wed, 06 Jan 2021 21:21:28 GMT

This would be used as an addressing grid.

The blue lines would be a whole section.

Range - address range, increase from right to left and south to north.

I guess I just need each sections to be broken into just 9 sections not 100.

The increase from right to left is just a 1000 of possible addresses.

Hopefully that helps.

Re: Split Polylines at certain increments

DanPatterson — Wed, 06 Jan 2021 21:33:32 GMT

Just do the mental math to come up with the rectangle width and height. There is no point in coming up with some script when the tools is already available for use.

Once you have the grid you can convert it to singleparts, explode it into segments., reorient line segments etc etc

Re: Split Polylines at certain increments

CCWeedcontrol — Wed, 06 Jan 2021 22:02:00 GMT

I have been messing the fishnet tool for a while and can't produce what i need.

I am thinking that some how each section length & high has to be calculated then divided evenly by 9 times?

Re: Split Polylines at certain increments

BlakeTerhune — Wed, 06 Jan 2021 22:17:36 GMT

Convert each section to a polygon just so it's easier to identify the extent of each one individually. Then pick one to be the template extent object of the fishnet extent and choose number_rows = 9 and number_columns = 9. Repeat that for each polygon section. You may need to clean up the edges a bit.

Re: Split Polylines at certain increments

CCWeedcontrol — Thu, 07 Jan 2021 22:35:37 GMT

Surely I am not the only one that has need to do this and I was hopping there would be something automated since what you describe would be time consuming but I appreciate the suggestion.

Re: Split Polylines at certain increments

BlakeTerhune — Thu, 07 Jan 2021 22:40:31 GMT

You can automate this process by iterating over each polygon with a search cursor.

Re: Split Polylines at certain increments

DanPatterson — Thu, 07 Jan 2021 22:50:39 GMT

It is also easy enough to add transect lines, just do one for each axis orientation.

Transect lines, parallel lines, offset lines - GeoNet, The Esri Community

Since it appears that you are working with a road network you north-south lines will always have offsets which are reflected in the grid pattern

Split (Analysis)—ArcGIS Pro | Documentation would be useful, but not on a micro scale. You would have to use "cut" in Polygon—ArcGIS Pro | Documentation if you want to code

Re: Split Polylines at certain increments

CCWeedcontrol — Fri, 08 Jan 2021 18:36:30 GMT

I was able to achieve creating the blocks with the following below but would be nice if could have populate the attributes based on a formula and this is beyond me. I attached the sections in case anyone wants to help out.

import arcpy, os arcpy.env.overwriteOutput = True def CreateFishnetsForFeats(shp, out, cell_x=0, cell_y=0, n_rows=0, n_cols=0): # Create file gdb to store data gdb = str(arcpy.CreateFileGDB_management(out, 'Fishnets.gdb').getOutput(0)) # spatial reference arcpy.env.outputCoordinateSystem = arcpy.Describe(shp).spatialReference # Loop thru rows of input polygons with arcpy.da.SearchCursor(shp, ['SHAPE@', 'OID@']) as rows: for row in rows: ext = row[0].extent st = '%f %f' %(ext.XMin, ext.YMin) ort = '%f %f' %(ext.XMin, ext.YMax) # Create fishnet outFn = os.path.join(gdb, 'fish_{0}'.format(row[1])) arcpy.CreateFishnet_management(outFn, st, ort, cell_x,cell_y, n_rows, n_cols, labels='NO_LABELS',template = ext, geometry_type='POLYGON') # set workspace to new gdb arcpy.env.workspace = gdb fishnets = arcpy.ListFeatureClasses() targ = fishnets[0] for i, fish in enumerate(fishnets): # Add field for original polygon ID fid = fish.split('_')[1] arcpy.AddField_management(fish, 'POLY_ID', 'LONG') with arcpy.da.UpdateCursor(fish, ['POLY_ID']) as rows: for row in rows: row[0] = fid rows.updateRow(row) # append fishnets into one feature class if i > 0: arcpy.Append_management([fish], targ, 'NO_TEST') arcpy.Delete_management(fish) print (*'Appended: {0}'.format(fish)) print ('Done') return if __name__ == '__main__': polys = r'C:\Temp\SectionGrid\SectionsCopy.shp' loc = r'C:\TEMP' CreateFishnetsForFeats(polys, loc, 0, 0, 9, 9)