Let's suppose now that the Iris names in the class column are too long or too complex for a task. We would like to have just class column that's called class one, class two, and class three. That is why we would like to add a column wherever it says Iris sutosa. We would like to replace that with a class one. For Iris versa color we would like to replace it with a class two, and so on. Nine has a very practical node called the rule engine node. This node to define a set of rolls on all of the values of the input data columns and generates new values according to the defined rule set. The new values can form a new column to append to the existing ones in the input data table, or we can actually replace the existing data column. So let's take a look at this. We're going to search for the rule engine node in the node repository. We're going to double click on it and then drag it back close to the column rename node. Now that we have renamed the last column, we're going to send the new version of our data set into the row engine. We're going to right-click to configure, and here is the configuration window for the rule engine node. We can see in the left-hand side the list of all the columns in our data set. Here we can see a list of all the functions that can be implied. And here is where we're going to write our expressions. We can see if we double click on the class, it brings start variable into the expression window and helps us create our rules. So we wanted to see wherever the class indicates a value of the input data being equal to iris setosa. So we double clicked on the class and we're going to see wherever it's equal. So we're going to double click on the sign. And we wanted to see where it equals to the Iris setosa. Make sure that you note that string values need to be encapsulated in between quotation marks to be correctly interpreted as strings by the rule engine note. And we're going to put quotation marks and write Iris setosa. When this is correct, we want this to input a word class one. We're putting that under quotation marks as well because we want that value to remain as a string. We can continue with when the class value equals to Iris-versicolor, then we would like to input class 2. Since we know we only have these three class values, we can say TRUE, which means anything else, the class will equal class 3. So this final keyword TRUE really represents the else value in our list of rules. And the values that is always true is no other rule is satisfied. To insert a new constant value in data column, we can just use TRUE and then implication sign to the new constant value. And we don't have to write any other rules. So let's apply and execute this rule. We can right click on the rule engine node, say Execute. And now we can right click and take a look at the classified values. You can see that every Iris setosa was replaced with the class 1. Every Iris versicolor was replaced with a class 2, and every Iris virginica became a class 3. Now if we wanted to replace this value instead of appending it, we would have clicked here, replace the column class. We said Append, so we added another column to the data sets that we had. So now you know know how to use a rule engine. This is a very useful and versatile note that you will probably find yourself using in many of your workflows.
