Application: gvSIG desktop » gvSIG scripting

import gvsig

import commonsdialog

def main(): 

  """

  This script runs all the features of the active layer, and calculates the 

  maximum and minimum elevation these, and with this:

    - Shows a message informing the user which are

    - Select the geometries associated with maximum and minimum elevation. 

  If no ELEVATION field shows a message and finish script execution.

  In the data folder can be found polygons_with_elevation layer used

  for testing with this script.

  """

  #

  #Invoke gvsig.currentLayer function to get active layer

  #If not view or active layer in view raise RuntimeException

  layer = gvsig.currentLayer()

  #

  #Invoke layer.getSchema method to get layer definition data 

  schema = layer.getSchema()

  #

  #Invoke schema.get method to get ELEVATION field or None

  field = schema.get('ELEVATION', None)

  #

  #Check if field exist

  if not field:

      #If not shows message and finish

      text = '"ELEVATION" field must exist in the active layer.\nFinish script'

      title = "ERROR"

      message_type = commonsdialog.WARNING

      commonsdialog.msgbox(text, title, message_type)

      return

  emax = 0.0

  emin = 0.0

  fmax = None

  fmin = None

  #

  # Gets features using layer.features method

  features = layer.features()

  #

  #Runs layer features

  for feature in features:

    # 

    # Cheacks if current feature ELEVATION is higher than calculated. 

    # If so, stored current ELEVATION value and the feature instance

    if feature.ELEVATION > emax :

        emax = feature.ELEVATION

        fmax = feature.getCopy()

    # Same but with minimum ELEVATION

    if feature.ELEVATION < emin or emin ==0.0:

        emin = feature.ELEVATION

        fmin = feature.getCopy()

  #

  # Selects features in the layer.

  if fmax!=None:

    layer.select(fmax)

  if fmin!=None:

    layer.select(fmin)

  #

  # Finally show results in a msgbox message.

  text = "Maximum Elevation=%s, Minumun Elevation=%s" % (emax, emin)

  title = "Maximun and minumum values"

  message_type = commonsdialog.IDEA

  commonsdialog.msgbox(text, title, message_type)