If X2 doesn't have the same ordering you wouldn't be able to pass that
directly either. The data is split before the being run into the pipeline,
so just using hstack is fine.
I've got the code I use to make this easier here by the way :
https://github.com/andaag/scikit_helpers .
On Fri, Aug 22, 2014 at 7:44 AM, Sebastian Okser <seo...@utu.fi> wrote:
> Hey,
>
> Your tip put me very far in the right direction. I have one further
> question. It seems that just appending the features in the featureunion as
> a pipeline step may create havoc as when I implement gridsearchcv the data
> is going to have some sort of randomness in the data order compared to the
> original dataset. Therefore doing something simply like:
>
> import numpy as np
>
> class FeatureStacker():
> """Class adds features to the data matrix"""
> def __init__(self,X2):
> """Initialization Function, X2 is the feature array of the
> features to be added"""
> self.X2 = X2
>
> #Other required functions in a transformer
>
> def transform(self,X):
> """Horizontally stacks elements X and X2"""
> return np.hstack((X,self.X2))
>
> Where X2 are the new features wouldn't necessarily have the same data
> ordering and would hurt the training. Is there anyway to preserve the
> splits in this and then apply it to the new data. For example, assuming
> that X = array([[1,2,3],[4,5,6],[7,8,9]]) and X2 = array([[11],[12],[13]]).
> Normally I would want to hstack them so that X_new =
> array([[1,2,3,11],[4,5,6,12],[7,8,9,13]]), but if the order has been
> shuffled due to the various instances falling into different folds, I don't
> think that it could be guaranteed that the X_new matrix will be generated
> in the same way as listed above.
>
> In short how can I account for the gridsearch's cv when doing the hstack
> in this situation? Thanks.
>
>
> Sebastian
> ________________________________________
> From: Sebastian Raschka [se.rasc...@gmail.com]
> Sent: Thursday, August 21, 2014 10:41 PM
> To: scikit-learn-general@lists.sourceforge.net
> Subject: Re: [Scikit-learn-general] Pipeline - Convert to dense
>
> Hi, Zoraida,
>
> thanks for the follow up! I went with a short, custom ColumnSelector
> class, but the itemgetter is even nicer.
>
> Best,
> Sebastian
>
> On Aug 21, 2014, at 2:57 PM, ZORAIDA HIDALGO SANCHEZ <
> zoraida.hidalgosanc...@telefonica.com> wrote:
>
> > Sebastian,
> >
> > a few days ago, I asked a very similar question and I got this link as a
> > response:
> >
> > https://github.com/scikit-learn/scikit-learn/issues/2034
> >
> >
> > I think that you could try something similar.
> >
> >
> > Best,
> >
> > Zoraida.-
> >
> > El 21/08/14 18:48, "Sebastian Okser" <seo...@utu.fi> escribió:
> >
> >> I am trying to use the pipeline combined with a countvectorizer,
> >> tfidftransformer and randomforest. However the output of the second step
> >> is a sparse array and randomforest requires a dense one. How can I add a
> >> step to allow for a conversion of the matrix from sparse to dense, using
> >> something along the lines of data.toarray(). Additionally, I would like
> >> to add some additional features to the dataset after the text has been
> >> processed. How can I create a step for this (normally I could use
> >> something like hstack)? My code is as follows:
> >>
> >> pipeline = Pipeline([
> >> ('vect', CountVectorizer()),
> >> ('tfidf', TfidfTransformer()),
> >> ('clf', OneVsRestClassifier(SVC(probability=True))),
> >> ])
> >> I would like to adjust this somehow to the following:
> >>
> >> pipeline = Pipeline([
> >> ('vect', CountVectorizer()),
> >> ('tfidf', TfidfTransformer()),
> >> ('change_to_dense', SOME HOW CHANGE TO DENSE),
> >> ('add_more_data', SOME HOW ADD FEATURES),
> >> ('clf', OneVsRestClassifier(SVC(probability=True))),
> >> ])
> >>
> >> My first dataset, lets call it data1 is just an array of sentences.
> Below
> >> is an example:
> >>
> >> data1 = ['This is the first sentence',
> >> 'This is the second sentence',
> >> 'This is the third sentence']
> >>
> >> The second dataset is numerical data of the following form:
> >>
> >> data2 = array([[0],
> >> [1],
> >> [0]])
> >>
> >>
> >> Thanks!
> >>
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