[scikit-learn] Problems with running GridSearchCV on a pipeline with a custom transformer

[Sam Barnett]

Dear all,

I have created a 2-step pipeline with a custom transformer followed by a
simple SVC classifier, and I wish to run a grid-search over it. I am able
to successfully create the transformer and the pipeline, and each of these
elements work fine. However, when I try to use the fit() method on my
GridSearchCV object, I get the following error:

     57         # during fit.
     58         if X.shape != self.input_shape_:
---> 59             raise ValueError('Shape of input is different from what
was seen '
     60                              'in `fit`')
     61

ValueError: Shape of input is different from what was seen in `fit`

For a full breakdown of the problem, I have written a Jupyter notebook
showing exactly how the error occurs (this also contains all .py files
necessary to run the notebook). Can anybody see how to work through this?

Many thanks,
Sam Barnett
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