binary operators on all estimators

abomination.py

from sklearn.base import BaseEstimator

def piper(self, other):
    from sklearn.pipeline import make_pipeline, Pipeline
    if isinstance(self, Pipeline):
        steps = ([estimator for (name, estimator) in self.steps] + [other])
        return make_pipeline(*steps)
    else:
        return make_pipeline(self, other)

def unionizer(self, other):
    from sklearn.pipeline import make_union, FeatureUnion
    if isinstance(self, FeatureUnion):
        steps = ([estimator for (name, estimator) in self.steps] + [other])
        return make_union(*steps)
    else:
        return make_union(self, other)

BaseEstimator.__rshift__ = piper
BaseEstimator.__mul__ = unionizer

On second though, should have called it "make @GaelVaroquaux cry"

Oh, no! You forgot to add that parameter renaming magic I once wrote so that all double-underscored parameter settings are eradicated forever and replaced with custom incantations. Without parameter renaming magic, est is far from substitutable with est >> est2.

@jnothman sorry just saw this. But I'm not following