Applying Python Scripts in Rulex Processes

The Python Bridge task allows you to perform statistical calculations via Python script on Rulex data, and either overwrite the original dataset with the output results, or create a new dataset (such as clusters or advanced association structures).

This type of task may be useful when you already have statistical algorithms in Python, and want to use them in Rulex without having to rewrite any of the logic.

The Python script can either be entered directly in the task, or a reference can be provided to an external script file.

Python dictionary format

The format data in python is a dictionary that associates to each column name (key) the list of values of the column itself (values), for example:

"age" : [39, 45,...] "workclass" : ["Private", "State-gov",...]

Prerequisites

a Rulex process has been created
Python 3 software has been installed where Rulex is running.
IPython3 has been installed on the machine where Rulex is running (via pip install ipython)

Additional tabs

The following additional tabs are provided:

Documentation tab where you can document your task,
Parametric options tab where you can configure process variables instead of fixed values. Parametric equivalents are expressed in italics in this page (PO).

Procedure

Drag and drop the Python Bridge task onto the stage.
Connect the task that contains the dataset on which you want to perform the Python script to the Python Bridge task.
Double click the Python Bridge task.
Configure the script options as described in the table below.
Save and compute the task.

Python bridge options

Python bridge options
Name	PO	Description
General options
Get input from	setref	Select the type of data you want to use as input for the Python script. Possible options are: Dataset (i.e. the main data table) Clusters Advanced association structure (association rules, bundle hypotheses or replacement rules table).
Name of the Rulex input table in Python script	rinputname	Enter the name you want to use within the Python script to reference the data received from Rulex. For example, if you selected Dataset in the Get input from option, and you enter Input as the name here in this option, the main Rulex data table will be referred to as a dictionary called "Input" within the Python script.
Get Python script from file	scriptfromfile	Select this option if you want to reference an external script file. Alternatively you can enter the script code directly in the Python Code edit box below. This edit box will be disabled if you decide to reference an external file to avoid confusion on which script will be applied.
Select Python script	filename	Click here and browse to the external file, which contains the Python script you want to apply. This option will be enabled only if you have selected the Get Python script from file option.
Store output in	outref	Select the type of table that will be populated by the dictionary selected as output in the Python script. Possible options are: Dataset (i.e. the main data table) Clusters Advanced association structure (association rules, bundle hypotheses or replacement rules table).
Name of the output dictionary in Python script	routputname	Enter the name you want to use in the Python script to reference the data Rulex will receive from Python. This data will populate the table according to the option selected in Store output in.
Select file to store Python console output	debugfilename	Browse to the text file where the Python script console output will be saved after execution of the Python Bridge task.
Python Code	rcode	Enter the Python script code you want to execute. This text box is enabled only if you ave not selected the Get Python script from file option.
Connection options
Select path to Python command	rcommand	Browse to the location of the IPython interpreter command, which can be found in the Python installation folder. If you have administrator rights on the machine, it will be sufficient to enter ipython3.exe. If the path is not correctly specified, the Python Bridge task will not work correctly and a warning message will be displayed. The Python task cannot compute if another process is pending. You can monitor this on Windows via the Task Manager (Processes).
Python host	rhostname	Enter the address of the host where Python is installed. If Rulex is running on the same desktop where it is installed you can enter localhost.
Python port	rport	Specify the port used for data transfer between Rulex and Python (i.e. input table transfer from Rulex to Python, output dictionary transfer from Python to Rulex). System firewall exception Make sure you define an exception in the system firewall on this port, allowing the data exchange between the two applications. Otherwise, the task will not be executed and a warning message will be displayed signaling a communication problem between Rulex and Python.
Python port for signals	rportaux	Specify the port used for signal transfer between Rulex and Python (i.e. progress bar updates).

Example

The following example is are based on the adult dataset.

In the scenario a very basic Python script will be applied to Rulex data, and the results will be viewed in a Data Manager task.

The following steps were performed:

We import the adult.set dataset.
We then add a Python Bridge task and enter the Python script code directly in the task options.
We finally use the Take a look function to check the results of the R script.

Procedure	Screenshot

Procedure

Screenshot

Importing the adult.set dataset via an Import from Text File task, taking the data types from line 2.

Add a Python bridge task to the process and configure it as follows:

Get input from: Dataset
Name of Rulex input table in Python script: inputdata
Store input in: Dataset
Name of the output dictionary in Python script: outputdata

Enter the following script in the Python Code text box:

outputdata = {}
outputdata["age_changed"] = [inputdata["age"][i]+7 for i in range(len(inputdata["age"]))]
outputdata["workclass_changed"] = [inputdata["workclass"][i]+"a" for i in range(len(inputdata["workclass"]))]

The code simply creates:

a new column called "age_changed" which is the same as the "age" column but with the addition of 7 years.
a new column called "workclass_changed" which is the same as the "workclass" column, but with an additional letter "a" added to the end of the name.

In the Connection tab, configure the following:

Select path to Python command: the path to the ipython3.exe command
Python host: localhost
Python port: an available port, e.g. 6001
Python port for signals: an available port, e.g. 6002

Save and compute the task, then right-click it and select Take a look to explore the results.

The two new columns have been created by the Python script, as we expected.