topic Re: Is there a way to speedup the following code in Python Questions

Is there a way to speedup the following code

AndrewNeedham1 — Thu, 14 Mar 2019 04:30:52 GMT

Hi,

Back story, this code is part of a much larger script which loops a few thousand times and takes a few days to finish

I'm currently going through the code and trying to it speed up where possible. Can the following code be speed up?

I know arcpy.da curses are fast but can they be used here?

Edit: This is using ArcGIS 10.3.1 and can't be transferred to ArcPro

# select Lines

whereClauseSort = """{} IN (1,2,3) AND {} = 'Pass' """.format('Sorting', 'Group2')

selectionLineFC = r"in_memory\line"

arcpy.Select_analysis(selectionFC, selectionLineFC, whereClauseSort)

# Dissolve selected lines

Dissolve1 = r"in_memory\Dissolve1"

arcpy.Dissolve_management(

selectionLineFC, Dissolve1, "Angle;BEARING",

"Sorting COUNT;Seam First", "MULTI_PART", "DISSOLVE_LINES")

# add attributes

arcpy.AddField_management(

Dissolve1, "Length", "LONG", "", "", "", "Length", "NULLABLE", "NON_REQUIRED")

arcpy.CalculateField_management(

Dissolve1, "Length", "round(!shape.length@meters!,10)", "PYTHON_9.3", "")

# Sort Dissolve selected lines

sort = r"in_memory\Sort1"

arcpy.Sort_management(

'Dissolve1', sort,

'Length DESCENDING;Angle ASCENDING;COUNT_Sorting ASCENDING', 'UR')

# Select first record

sort2 = r"in_memory\Sort2"

sel = arcpy.Select_analysis(sort, sort2, 'OID = 1')

# Buffer first record

convexHullBuff = r"in_memory\convexHullBuff"

convexHullbuff = arcpy.Buffer_analysis(

sel, convexHullBuff, '200 Meters', 'FULL', 'ROUND', 'NONE', '#', 'PLANAR')

# CONVEX_HULL of Buffered first record

ConvexHull = r"in_memory\ConvexHull"

convexHull = arcpy.MinimumBoundingGeometry_management(

convexHullbuff, ConvexHull, "CONVEX_HULL", 'NONE', '#', 'NO_MBG_FIELDS')

Re: Is there a way to speedup the following code

DanPatterson_Retired — Thu, 14 Mar 2019 05:05:37 GMT

What is your end goal? Can you explain the purpose of those blocks of code?

Do you get different results for instance, if you determine the convex hull, then buffer vs the way you have it?

If you have complex shapes, the more points you have the longer the buffer is going to take

Also, In some cases, just working with the arcpy geometry methods and properties is faster than calling the arctoolbox tool that does the same thing (eg, like a dissolve). Other times using numpy for geometry functions is orders of magnitude faster.

Re: Is there a way to speedup the following code

AndrewNeedham1 — Thu, 14 Mar 2019 05:35:42 GMT

The end goal is to run the script faster that it currently is. The order needs to be maintained such as, if you don't buffer the selected line\s (multipart) the convex hull will fail on a single line.

Yes the goal would be to use arcpy geometry methods, but I am unaware of the syntax/code for arcpy geometry methods to do a dissolve, do you have an example of this?

Re: Is there a way to speedup the following code

curtvprice — Sat, 11 Dec 2021 07:32:13 GMT

Your physical sort is really slow, setting up a sorted cursor is a much faster way to get the first-sorted record. Here's my suggested fix for this:

# Sort Dissolve selected lines
sort = r"in_memory\Sort1"
arcpy.Sort_management(
'Dissolve1', sort,
'Length DESCENDING;Angle ASCENDING;COUNT_Sorting ASCENDING', 'UR')
# Select first record
sort2 = r"in_memory\Sort2"
sel = arcpy.Select_analysis(sort, sort2, 'OID = 1')‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

if the data are in a file geodatabase, you can use ORDER BY with a search cursor instead of a (slow) sort to find the first OID (sorted)

xdis = arcpy.CopyFeatures_management(Dissolve1, arcpy.env.scratchGDB + "/xdis")
oid = arcpy.da.SearchCursor(xdis, "*", "", "",
  ["", "ORDER BY Length DESC, ANGLE ASC, COUNT_Sorting ASC"]).next()[0]
sort2 = arcpy.Select_analysis(xdis, 'in_memory/sort2', 
          'OID = {}'.format(oid))‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Is there a way to speedup the following code

DanPatterson_Retired — Sat, 11 Dec 2021 07:32:16 GMT

For the polygon class for instance, Polygon—ArcPy classes | ArcGIS Desktop

you can find the geometry functions like convex hull in there

similarly for length etc.

You can create arrays do quick calculations resulting in the equivalent of a field, then use arcpy.ExtendTable, which effectively, allows you to do vectorized calculations, and add the result to a table.

You can accomplish many tasks at once. For example, you need the perimeter of a buffered polyline's convex hull.

Your worst case scenario, a 2 point polyline parallel to the x-axis

p0 = arcpy.Point(0,0)
p1 = arcpy.Point(10,0)
poly = arcpy.Polyline(arcpy.Array([p0,p1]))
polybuff = poly.buffer(2)
ch = polybuff.convexHull()
ch.length
Out[171]: 32.55081089915268‍‍‍‍‍‍‍

of course this doesn't have to be done line-by-line, but you read the geometry, buffer (line 4) do the convex hull (line 5), get its length and add it to a field. That whole sequence can be a 'def' for use in the field calculator for example

Re: Is there a way to speedup the following code

AndrewNeedham1 — Thu, 14 Mar 2019 06:10:33 GMT

Thanks. I will look into this, it will take some time to get my head around this code

Re: Is there a way to speedup the following code

AndrewNeedham1 — Thu, 14 Mar 2019 06:21:10 GMT

Awesome thanks, I haven't seen a search cursor used in that way before. I would assume the Dissolve FC could be used directly into the Search Cursor instead of using the Copy Features. Thus eliminating an extra step?

Re: Is there a way to speedup the following code

curtvprice — Thu, 14 Mar 2019 16:05:51 GMT

I would assume the Dissolve FC could be used directly into the Search Cursor instead of using the Copy Features. Thus eliminating an extra step?

I don't believe the ORDER BY will work using an in_memory feature class.