Using field names on output filename in arcpy

Question

I am trying to write a loop in arcpy that will first make a selection by attribute in one feature class and then make a selection by location on another. Then I want to copy the selected features into a gdb and move to the next row in the table.

This works just fine when I use a numeric uniqueID, but I want to have the output filename retrieve a value from the attribute table (A string with the feature's name) instead of giving me "Pand + string_x" which is just a number.

This is the script:

x=1

while x < 389:

string_x = str(x)

x_input = "UniqueID = " + string_x

x_output = r"C:\temp\BaseMap\working_data\BAG.gdb\Pand_" + string_x

arcpy.SelectLayerByAttribute_management("gemeente2017","NEW_SELECTION", x_input)

arcpy.SelectLayerByLocation_management("Pand","HAVE_THEIR_CENTER_IN","gemeente2017","","NEW_SELECTION","NOT_INVERT")

arcpy.CopyFeatures_management("Pand",x_output, "")

x += 1

I'm guessing the solution will have something to do with Field delimiters, but I'm quite new at this and have no idea how to incorporate that into my code. Using ArcGIS 10.5 and Python 2.7.12.

Answer 1

You need to create a loop using the Arcpy.da.SearchCursor on your featureclass. This will accomplish this without using a for/while loop on numbers.

1. Create Feature Layers so you can apply selections
2. Create a Search Cursor on your main feature layer
3. Apply an expression to select your row
4. Use SelectbyLocation to identify the intersected features
5. Export this to a new featureclass

Try the following:

fc = r"path/to/fc"
fc_fl = arcpy.MakeFeatureLayer_management(fc, "fc_fl")

intersect_dataset = r"path/to/fc"
int_fl = arcpy.MakeFeatureLayer_management(intersect_dataset, "int_fl")

OID = arcpy.Describe(fc_fl).OIDFieldName

#update the "field_with_feature_name" to a field that has the output name
with arcpy.da.SearchCursor(fc_fl, OID + ["field_with_feature_name"]) as cursor:
    for row in cursor:
        #create an expression to identify the objectid in the density grid
        expression = '"{}" = {}'.format(OID, row[0])

        #create a selection on that row
        arcpy.SelectLayerByAttribute_management(fc_fl, "NEW_SELECTION", expression)

        #identify the intersect features
        arcpy.SelectLayerByLocation_management(int_fl, "INTERSECT", fc_fl)

        #export to new fc
        arcpy.CopyFeatures_management(int_fl, "Pand_{}".format(row[1]))

       #remove selections
        arcpy.SelectLayerByAttribute_management(fc_fl, "CLEAR_SELECTION")
        arcpy.SelectLayerByAttribute_management(int_fl, "CLEAR_SELECTION")

Answer 2

By Creating a instance of your selection in a new variable with the result of arcpy.selectionByLocation_management([your request]) , it could be more efficient Afet look for the right field.name value with SearchCursor

[...]

FC=arcpy.SelectLayerByLocation_management("Pand","HAVE_THEIR_CENTER_IN","gemeente2017","","NEW_SELECTION","NOT_INVERT")
field_name = 'yourFiedName'
SC = arcpy.da.SearchCursor(FC,  field_name)

for row in SC:
    for cell in row: #Iterate through row, which is a Python list
        print cell #Print value of item in row list
        fieldNameValue = cell

del SC

x_output = r"C:\temp\BaseMap\working_data\BAG.gdb\Pand_" + fieldNameValue

[...]

Answer 3

Thanks Hugo it worked! This is how the code looks like now:

x =1
while x < 389:
    string_x = str(x)
    x_input = "UniqueID = "+ string_x
    fc = arcpy.SelectLayerByAttribute_management("gemeente2017", "NEW_SELECTION", x_input)
    field_name = "Gemeentena"
    sc = arcpy.da.SearchCursor(fc, field_name)
    for row in sc:
        for cell in row:
            print cell
            fieldNameValue = cell
del sc
arcpy.SelectLayerByLocation_management("Pand", "HAVE_THEIR_CENTER_IN","gemeente2017, "", "NEW_SELECTION", "NOT_INVERT")
x_output = r"c:\temp\Basemap\working_data\BAG.gdb\Pand_"+ fieldNameValue
arcpy.CopyFeatures_management("Pand", x_output, "")
x += 1