topic PYTHON Using a 'for' loop (ex. for i in list:) to create a series of shapefiles to use to create TINs in Python Questions

PYTHON Using a 'for' loop (ex. for i in list:) to create a series of shapefiles to use to create TINs

petegillard — Tue, 10 Nov 2020 19:07:29 GMT

i'm trying to select a set of depth values (points - ex. 2902, 2904, 2906, etc.)from surveyed points. save those to their own point layer, convert those to a TIN, then calc. Volumes. My approach was to make a list of the values, use those values as VARIABLES to create a series of shapefiles (shp2906, shp2908, etc.) then create TINs from those. Hard coding the numbers it works, but wanted to pass the depth values (using "select" (ex. grid_code le 2906)) name the shapefile and the tin (ex. tin2904, tin 2906, etc) was hoping to use the iteration as a variable, but it's not liking any of my attempts...... thanks in advance, for any ideas....

Re: PYTHON Using a 'for' loop (ex. for i in list:) to create a series of shapefiles to use to create TINs

JoshuaBixby — Tue, 10 Nov 2020 20:44:04 GMT

It is always best to share some of your code, often times it is easier to interpret code than someone's explanation of their code.

Re: PYTHON Using a 'for' loop (ex. for i in list:) to create a series of shapefiles to use to create TINs

Marc_Graham — Sun, 12 Dec 2021 16:53:32 GMT

Hi there,

I think this may help. It looks through a list of depths and exports a feature class from the source data that is queried for each depth, and then also a tin. It's just a quick hack so there's no error handling etc. Also I'm not sure how to properly embed code, hopefully this works.

Cheers,

Marc

# IMPORT ARCPY
import arcpy
arcpy.OverwriteOutput = True

# SCRIPT VARIABLES
sr = arcpy.SpatialReference(2193)

# MAKE SURE INPUT AND OUTPUT DATA/GDB EXIST
out_fgdb = r"C:\Temp\out.gdb"
out_folder = r"C:\Temp"
surv_pts = r"C:\Temp\s_pts.shp"
surv_lyr = arcpy.MakeFeatureLayer_management(surv_pts)
depth_list = [1,2,3,4,5]

# VALUES FOR TIN CREATION
depth_field = "depth"
tin_type = "Mass_Points <None>"

# ITERATE THROUGH DEPTHS, OUTPUT FEATURE CLASSES AND TINS
for d in depth_list:
 fc_name = "points_{}".format(d)
 fc_path = "{}\{}".format(out_fgdb,fc_name)
 query = "depth = {}".format(d)
 tin_path = r"{}\tin_{}".format(out_folder,d)

 # CREATE A FEATURECLASS IN THE OUTPUT FGDB
 arcpy.FeatureClassToFeatureClass_conversion(surv_lyr, out_fgdb, fc_name, query)
 tin_def = "{} {} {}".format(fc_path, depth_field, tin_type)

 # CREATE A TIN IN THE OUTPUT FOLDER
 arcpy.CreateTin_3d(tin_path,
 sr,
 tin_def,
 constrained_delaunay="DELAUNAY")

Re: PYTHON Using a 'for' loop (ex. for i in list:) to create a series of shapefiles to use to create

petegillard — Thu, 12 Nov 2020 13:51:32 GMT

thanks, thought of that...…...everywhere in the code below "2922" is the depth. I was trying to pull from a "list" of depths to use as a variable (we're looking at volume of water at 2ft. depth intervals ). This code worked, but was hoping to automate it.

# Import arcpy module import arcpy from arcpy import env arcpy.CheckOutExtension("3D") # Local variables: UPDpts = r"Y:\GIS\Pete\resPTS_test\UPDFk_pts_Clip.shp" le2922 = r"Y:\GIS\Pete\resPTS_test\le2922.shp" le2922tin = r"Y:\GIS\Pete\resPTS_test\le2922tin" #proj = r"Coordinate Systems/Projected Coordinate Systems/State Plane/State Plane NAD 1983 (2011) Montana FIPS 2500 (Intl Feet).prj" proj = arcpy.SpatialReference ("NAD 1983 (2011) StatePlane Montana FIPS 2500 (Intl Feet).prj") # Process: Select arcpy.Select_analysis(UPDpts, le2922, "grid_code <= 2922") # Process: Create Tin arcpy.CreateTin_3d("le2922tin", proj,"le2922.shp grid_code masspoints" " ") arcpy.DelineateTinDataArea_3d("le2922tin", 11, "PERIMETER_ONLY") # Process: Calc. volume arcpy.SurfaceVolume_3d("le2922tin", "tin2922_vol.txt", "BELOW", 2922, 1)

Re: PYTHON Using a 'for' loop (ex. for i in list:) to create a series of shapefiles to use to create

petegillard — Thu, 12 Nov 2020 13:52:24 GMT

thanks, i'll see if I can decipher this....appreciate the help

Re: PYTHON Using a 'for' loop (ex. for i in list:) to create a series of shapefiles to use to create

Michael_Boyce — Fri, 13 Nov 2020 02:07:53 GMT

G'day Peter and Marc,

Marc, that script looked like it should work pretty well. I haven't run it but what you have got down should go pretty well.

The only change that I would make would be to build the "Depth_List" dynamically by iterating through the original tables "Depth" field and adding them to the Depth List and converting it into a "set", which will ensure that there is only one value for each depth.
so...
adding in the following should help.

depthList = [row[0] for row in arcpy.da.SearchCursor(originalTable, depthField)] depthset = set(depthList)

or to make it even smaller:

depthSet = set([row[0] for row in arcpy.da.SearchCursor(originalTable, depthField)])

Hope you find the answer,

Michael