Executing Python Script based on Marking Selection

Usually Spotfire allows us to execute the Python script on a Property Change or Action Control Button. However lot of times there is a need to execute a script based on markings in a visualization for better User experience. 

Prerequisites:-
 - Spotfire Marking concepts
 - Property Controls/Document Property
 - Python Script
 - Statistical Server in your project (TERR)


Below is one of the use case:
Lets consider a scenario where in we have 3 visualizations in a page and lets say the visualizations are Level 1, Level 2 and Level 3. Level 2 data is filtered based on marking selection from Level 1 and similarly Level 3 based on Level 2 marking selection.

Step 1: After the marking selection is made at Level 1 and Level 2, Level 3 visualization is populated accordingly. 

Step 2: The moment we change the marking of Level 1, Level 2 visualization data will get updated and even though if no marking is done at Level 2, Level 3 visualization is populated based on the marking selection made on level 2 at Step 1 (kind of stale marking selection) and users would get confuse with the data at level 3 as we made the different selection on Level 1 at Step 2.   

In order to show the Level 3 visualization as Blank whenever Marking is updated at Level 1 visualization, we would need to execute a python script for the same.


Below is the python script for reference

# Import required libraries

from Spotfire.Dxp.Data import *

from Spotfire.Dxp.Application.Filters import *

def resetMarking():

# Loop through each data table

     for dataTable in Document.Data.Tables:

# Selecting the datatable(s) for which we need to unmark

             if dataTable.Name=="2":

# Navigate through each marking in a given data table

                         for marking in Document.Data.Markings:

# Selecting the Marking(s) which we need to reset

                                   if marking.Name=="D2":  

                                         rows = RowSelection(IndexSet(dataTable.RowCount, False))

                                         marking.SetSelection(rows, dataTable)

resetMarking()

Lets assume we have created the python script and now the goal is to trigger the script each time whenever marking gets updated.

 Steps to trigger Python Script based on Marking:

1) Register a new Data Function(TERR) with the script as below
    DocProperty <- Input

2) Set the Input Parameters and Output Parameter types



3) Click on Run button

4) Identify a KEY column in the data table  & apply some Aggregation Function (like UniqueCount, UniqueConcat,Sum, etc as per your data) and consider it as Input for the R- script, so that we can assign this value to the Document Property.
While defining the R Script Parameters, select the Marking on which we would need to execute the python script as below



5) The unique value which is generated from the expression based on the Marking selection (step 4). Now, we are assigning this value to one of the Document Property as below,
 

6) Assign the Python Script which we have created to this Document Property


7) Make sure to check the box 'Refresh function automatically'

8) If R-Script identifies any value change in the Input Parameters (our Input Parameters are evaluated based on marking selection), it would assign the value to the Document property and thus there is a change in the document property, python script will be executed.

Hope this would solve the Problem..! :)