To my knowledge, MLTK do not have any algorithm specific to imbalance dataset but they do have a github app i.e. a repo/app for algorithms: https://splunkbase.splunk.com/app/4403/ and it uses MLTK libraries.
One of the algorithm under github app modifies the DecisionTreeClassifier and has a class weight parameter added to it.
So install github app and make it global and use the following
.| fit CustomDecisionTreeClassifier class_weight="{'Yes':1,'No':0.1}">
Need to check the algo before installing github app, then checkout : https://github.com/splunk/mltk-algo-contrib/blob/master/src/bin/algos_contrib/CustomDecisionTreeClassifier.py
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