Need python equivalent to Avenue’s “ReturnContour”

RebeccaStrauch__GISP

I’m working on updating one of my old Avenue scripts.

Short description (of this particular problem in a longer process): given a set of random points within a study area, I need to create a contour at the elevation value of the random point, and using that as the center, create a transect on that contour at a given length, 50% in each direction….adjusting if necessary to keep within the study area.  (and there are other factors I don’t need to get into right now).

I’ve been able to grab the xy from a given point, and retrieve the value from the raster. The problem I am having right now is I can’t find an arcpy replacement for  ReturnContour (as shown in this line)

theFullContour = ElevTheme.GetGrid.ReturnContour(p, z, Prj.MakeNull)

My guess is it a NumPy solution (Dan Patterson maybe??), but I’m not sure what to search for.  Once I get the (poly)line, I should be ok with geometries.)

Does anyone have a simple way in python to return a single contour given an x/y/z and a raster?  Anyone in Geoprocessing or Imagery and Rasters  ??  Please, python solution only....no C#/arcobjects.

Thanks!

EDIT:  meant to include a snippet of test code for getting the point, in case anyone wants to test on their own data.  I'm grabbing point 7 of 2000 because I know it will return a good contour (some will not....too flat, which is handled elsewhere)

myPoints = r"C:\ADFG.gdb\myRandomPts2"
theDEM = r"C:\ADFG.gdb\DEM20aExtent"
cnt = 1
for row in arcpy.da.SearchCursor(myPoints, ["SHAPE@XY"]):
    if cnt == 7:
        x,y = row[0]      
        print("{}, {}, {}".format(cnt, x, y))
    else:
        pass
    cnt = cnt + 1
    
#x, y = 377906.9379, 1538997.6698
print("{}, {}".format(x, y))
ptLoc = str(x) + ' ' + str(y)

z1 = arcpy.GetCellValue_management("DEM20aExtent",ptLoc)
print(z1)

Message was edited by: Rebecca Strauch added code snippet

DanPatterson_Retired

Rebecca... Tooootally not checked out, but on the list.  One of the problems is that the Spatial Analyst tools and arcpy.sa don't provide much in the way of interacting with the dataframe, however, this...

Contour List—Help | ArcGIS for Desktop holds some promise

ContourList (in_raster, out_polyline_features, contour_values)

Parameter	Explanation	Data Type
in_raster	The input surface raster.	Raster Layer
out_polyline_features	The output contour polyline features.	Feature Class
contour_values [contour_value,...]	List of z-values for which to create contours.	Double

​IF you can pass the z-value of the location to the contour_values list.  Totally conjecture, but it seems to be the only on that doesn't require you to contour the whole surface specifying a base contour and interval.  Give it a shot

EDIT

just saw your edit, see if you can throw that z value into the contour list

I would suggest being specific rather than general  when using the tool

arcpy.sa.ContourList(... , ... , [elevation value in list] )