CODEWITHSUNDEEP
pythonscikit-learn
Pallen
Pallen

Reputation: 141

Why does FunctionTransformer pass check_inverse?

How come the check_inverse parameter in FunctionTransformer does not throw an error?

In the FunctionTransformer documentation, the parameter check_inverse is defaulted to be True, and as far as I understand it, it checks that, for an array X, that f^-1(f(X))=X.

In the example given, it removes the first column of the array X. How come removing the first column, which is not an invertible operation, pass the test?

I was expecting there to be a warning that the condition is not fulfilled.

Upvotes: 1

Views: 106

Answers (1)

pythonic833
pythonic833

Reputation: 3224

The reason for this is sadly only provided if you read the code. If no inverse function is given, the check is not applied:

if (self.check_inverse and not (self.func is None or
                                        self.inverse_func is None)):
      self._check_inverse_transform(X)

from FunctionTransformer.

Upvotes: 2

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