Printing name of field with highest value?

Question

I am trying to find the field with highest area value in each row of the 5 fields. Now I have found the highest value. But it doesn't really do me any good if I couldn't find which field is that max.

I have some rudimentary understanding and practice of Python. The very similar answer here:

need to find max value among fields AND PRINT FIELD NAME

When I applied the code, it always gave me a failure, which is probably due to my lack of understanding of Python.

Error 000539, Python syntax.

The code I adapted from that question is shown as below:

import arcpy

table = "L:\......\ParcelSummary.dbf"
fields = [ !SUM_acres_! , !SUM_acres1! , !SUM_acre_1! , !SUM_acre_2! , !SUM_acre_3! ]
n = len(fields)


maxfield = "Highest"
maxname = "HighestF"
arcpy.AddField_management(table, maxfield, "FLOAT")
arcpy.AddField_management(table, maxname, "TEXT")

fields2 = fields[:] # shallow copy
fields2.extend([maxfield, maxname])

with arcpy.da.UpdateCursor(table, fields2) as cursor:
for row in cursor:

    check = row[:n]
    maxval = max(check)

    row[-2:] = maxval, fields[check.index(maxval)]

    cursor.updateRow(row)

Also, a pretty basic question about this: shall I put the code into the Field Calculator expression or shall I put it in Pre-Logic Script Code? If I put them in the Codeblock, then what shall my expression be?

As for the field names, the ones shown in the picture are the aliases of the fields instead of names.

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My exact process and the error message I got.

Seems like the error is from line 1

The picture above shows the first few lines of the expression, what could have gone wrong here?

Answer 1

This should work:

def compMaxField(table, fields, maxFldName, maxValName):
  arcpy.AddField_management(table, maxFldName, 'TEXT') # field name with max value
  arcpy.AddField_management(table, maxValName, 'FLOAT') # the max value
  with arcpy.da.UpdateCursor(table, fields + [maxFldName, maxValName]) as cur:
    for row in cur: # everything inside a context must be indented
      maxVal = max(row[:-2]) # get the max value, skip the output fields
      maxFld = fields[row.index(maxVal)] # find out the corresponding field name
      # make a new row
      row = list(row[:-2]) + [maxFld, maxVal]
      cur.updateRow(row)

Place this into the pre-logic section, then just call it from the calculator like this:

compMaxField("L:\\......\\ParcelSummary.dbf",
             ['SUM_acres_' , 'SUM_acres1', 'SUM_acre_1', 'SUM_acre_2', 'SUM_acre_3'],
             'MaxArea', 'MaxField')

As @Florjan said, the backslashes in the path should be double-escaped, or you can use a raw string with the r prefix.

Answer 2

Before the dbf-file insert "r" letter:

table = r"c:\.....\name.dbf"

Change the expressed field names and if you take any error share it:

fields = [ "SUM_acres_" , "SUM_acres1" , "SUM_acre_1" , "SUM_acre_2" , "SUM_acre_3" ]