what are Pipelines

pipelines chains together multiple steps so that the output of each step is used as input to the next step

pipelines make it easy to apply the same preprocessing to train and test!

if you are planning to use Pipeline then

and if you want to implement a classifier like DecisionTreeClassifier or RandomForestClassifier call (.fit) not (.fit_transform)

if you do not want to use the classifier then (.fit_transform) will perform great

credits:https://www.youtube.com/watch?v=xOccYkgRV4Q&list=PLKnIA16_Rmvbr7zKYQuBfsVkjoLcJgxHH&index=36