Calculate Field with Python/ Arcade

NoahLeimgruber

HI all!

I want to execute a Python/Arcade command in ArcGIS Calculate Field which gives me a result for the catchment area (table).
The command should select all IDs in the list that have an X-value greater than the ID to be calculated (Here ID 1) and a Y-value less than the ID to be calculated (Here ID 1).
From the selected IDs, the respective areas should then be summed up and saved to the catchment area field.

In this example, the X and Y values of IDs 2 and 3 fulfill the condition. Thus, the respective areas would be added together, which would result in 15. The result would be stored in the catchment area of ID 1.

Thank you very much for your help!

 

ID	X	Y	area	catchment area
1	1000	2000	23	? (15)
2	1034	1083	10	…
3	1599	1743	5	…
4	1403	2004	34

XanderBakker

Hi @NoahLeimgruber ,

It seems to be working:

 

 I did notice that there are some polygons that have -1 for the H1 and H2 values and many have an H2 values that is equal to H1 +1. When selecting only those polygons that are larger than H1 and smaller than H2, you will not get any resulting polygon and a catchment area of 0. Is that correct?

 

The code I used is:

def main():
    # load arcpy
    import arcpy

    # set reference to the featureclass
    fc = r'D:\GeoNet\CatchmentArea\Data.shp' # change this

    # create dictionary with H values and areas
    flds1 = ("OID@", "H1", "H2", "SHAPE@AREA")
    dct = {r[0]: [r[1], r[2], r[3]] for r in arcpy.da.SearchCursor(fc, flds1)}

    # start update cursor to write the catchment areas
    flds2 = ("OID@", "Einzugsgeb")
    with arcpy.da.UpdateCursor(fc, flds2) as curs:
        for row in curs:
            # read values
            oidcurr = row[0]
            # determine catchment area
            catchment = SumAreaInRangeH(oidcurr, dct)
            row[1] = catchment
            curs.updateRow(row)


def SumAreaInRangeH(oidcurr, dct):
    # function to determine catchment area
    sumarea = -1
    if oidcurr in dct:
        # set reference values
        h1 = dct[oidcurr][0]
        h2 = dct[oidcurr][1]
        sumarea = 0
        for oid, lst in dct.items():
            if oid != oidcurr and lst[0] > h1 and lst[1] < h2:
                sumarea += lst[2]
    return sumarea


if __name__ == '__main__':
    main()