Using SearchCursor to round in ArcPy?

Question

I'm pretty novice at Python and I'm trying to employ a search cursor to round a field in a table in ArcGIS.

cursor = arcpy.SearchCursor(table,'', '', 'Distance')

for row in cursor:
    round(cursor, 3)

I'm receiving a "TypeError: a float is required" message.

Does anyone have any suggestions?

Answer 1

@smiller is correct: row in your code is essentially a tuple, which doesn't have a 'round' method. The following syntax should work. It uses an update cursor and assumes you want to replace the non-rounded values with rounded ones:

with arcpy.da.UpdateCursor(table, ["Distance"]) as cursor:
    for row in cursor:
        row[0] = round(float(row[0]), 3)  # Uses float() in case distance is a string            
        cursor.updateRow(row)

If you'd like to make a new attribute for the rounded result:

arcpy.AddField_management(table, "Rounded", 'DOUBLE')
with arcpy.da.UpdateCursor(table, ["Distance", "Rounded"]) as cursor:
    for row in cursor:
        row[1] = round(float(row[0]), 3)
        cursor.updateRow(row)