How to discretize a numerival value with predefined ranges in Weka? I have imported a csv file into Weka. One of the features has a value with minimum 0 and maximum 160. Now, I want to discretise that value into three ranges as you can see below:

Less than 6 > L

More than 6 and less than 20 > M

More than 20 > H

How can i do that?
Discretising or binning, very common. There is a filter for that in Weka. You'll find it under weka.filters.unsupervised.attribute.Discretise. It is in the GUI too. 

You can find the documentation under: https://weka.sourceforge.io/doc.dev/weka/filters/unsupervised/attribute/Discretize.html