Je n'ai pas utilisé de curseurs Arc 10.1, mais c'est apparemment encore plus facile là-bas.
Dans 10.0, il y a plusieurs façons de procéder, mais voici une approche de base pour débutants:
# Create a cursor on a feature class
cur = arcpy.UpdateCursor(myFeatureClass)
# Loop through the rows in the attribute table
for row in cur:
# The variable sqMiles will get the value from the column
# named 'Area_Miles'
sqMiles = row.getValue('Area_Miles')
# Calculate how many acres
acres = (sqMiles * 640)
# Assign the acres to a column named 'Area_Acres'
row.setValue('Area_Acres', acres)
# Apply the change
cur.updateRow(row)
# The loop will then move on to the next row/feature
Une version plus simple et condensée:
cur = arcpy.UpdateCursor(myFeatureClass)
for row in cur:
row.setValue('Area_Acres', row.getValue('Area_Miles') * 640)
cur.updateRow(row)
Voir: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//000v0000003m000000