Using Arcpy UpdateCursor to make calculations based on multiple fields?

Question

I'm new to Python.

I would like to calculate field values for a specific 'IDF' based on values from another column. I have something like that:

with arcpy.da.UpdateCursor(fc, ['IDF', 'og70_79_sales_sum','SUM_og70_79_103_sales']) as cursor:
for row in cursor:
 if row[0] == 103:
 row[1] = row[2]
 cursor.updateRow(row)
 print('{} - IDF, {} - value, update og70_79_sales_sum: {}'.format(row[0], row[2], row[1]))

but it does not work.

• Marcelo Villa: Are you sure the IDF field is numeric? It might be a string causing your condition to be False everytime
• Robert K.: Yes, IDF is numeric field (double).
• Robert K.: When in "row[1] = row[2]" instead of row [2], I enter a value, for example 100 it is ok. Fields 'og70_79_sales_sum' and 'SUM_og70_79_103_sales' are of the same type.
• Aaron: You need to fix your formatting--the for loop block needs to be indented. The cursor.updateRow(row) statement needs to be unindented so that it is directly within the for loop. What is the error you are getting?
• Robert K.: I'm not getting any error. Fields are still empty.

Answer 1

You stated in a comment that IDF is a Double field. However, you are comparing it to an integer, so your if statement is probably failing. Try converting the float to an int for the comparison:

if int(round(row[0])) == 103:

As an aside, I would highly recommend storing ID fields as Long/Short/Text, never Float/Double, because comparisons against Float/Double can be extremely unreliable as you see here.

• Dan C: +1 for never using a float or double field to store an ID value.