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Tutorial 4 - Connection Functions

Connection functions combine data from different files and return a new GIS file or a table as an output. To execute a connection mark all files you want to include in the calculation algorithm and add the connection before execution.

Too add connection functions at least two files have to be highlighted. Connection functions can be added

  1. through the menu by selecting Edit>Add>Connection,
  2. by clicking right on one or more selected files Add>Connection
  3. or using the shortcut Cntrl-C.

Select a connection function from the list that appears in the next dialog.

After adding a connection function the corresponding dialog will appear. Define the output filename output fileset by selecting it in the treeview.

You can also create a new subfolder within the selected fileset for your output by checking the box and naming the subfolder. Press the Ok Button to add the Connection Function.

The connection will be added to the defined folder under the given name. Specific settings can be made within the dialog opening when double clicking at the specific connection icon within the file tree.

In case of the Connection "Mean" the settings window looks like this:

The connection function Mean calculates the arithmetic mean value for each unit over more than one selected file for each unit.NODATA values are excluded from the calculation. Optionally relative values can be calculated as a percentage of the mean in relation to one the selected file "relative source".

To execute Connections select the file or files either

a. go to Edit→Execute→Connection,
b. use the shortcut Cntrl-Alt-C or
c. click right on the file or the files and select Execute→Connection.
d. Alternatively you can also execute all connections in your whole filetree at once by clicking at the icon at the toolbar.

The execution progress is displayed in a process tree that can be closed after all processes have been executed or cancelled.

After executing the Connection a new file has been created at the place where there has been the grey connection symbol before. The symbol is replaced with a hardcopy file with the orange coloured symbol attached. The file can now be treated as any other imported file.

The information about the settings of the file can be seen in the middle information panel under the heading Connection. In this case you can see which files were part of the subtraction and how the properties of the calculation were set.