[MRG+2] add get_feature_names to PolynomialFeatures #6372

amueller · 2016-02-16T21:03:41Z

Fixes #6185, replaces #6216

amueller · 2016-02-16T21:14:43Z

jnothman · 2016-02-16T21:26:59Z

sklearn/preprocessing/data.py

@@ -1182,6 +1182,35 @@ def powers_(self):
        return np.vstack(np.bincount(c, minlength=self.n_input_features_)
                         for c in combinations)

+    def get_feature_names(self, input_features=None):


I've been suggesting for a while that this is an appropriate way to deal with feature names in extractor/transformer pipelines. I'm happy to see this.

+1. Very nice.

I've been wanting to do it but didn't have time. I'm just writing the book chapter about preprocessing and I'm embarrassed not having that feature ;)

Hey, who knew writing books would be good for something?

jnothman · 2016-02-16T21:28:07Z

LGTM.

jnothman · 2016-02-16T21:31:37Z

I qualify that LGTM. I think we need to decide whether x_1, x_2, ... is the appropriate naming scheme. If we are to go with get_feature_names transforming its input feature name list, the same convention will apply in, e.g. feature selectors and feature agglomeration.

A further small issue: should these be unicodes in Python 2? We should at least test that when unicode input names are passed, an error is not triggered.

jakevdp · 2016-02-16T21:40:55Z

sklearn/preprocessing/data.py

+        ----------
+        input_features : list of string, length n_features, optional
+            String names for input features if available. By default,
+            "x0", "x1", ... "x_n_features" is used.


Should have underscores (x_0, x_1) to match code below.

Maybe it would be cleaner without underscores? I find things like x_1^2 x_2^1 harder to visually parse than x1^2 x2^1

yeah... well I was thinking about latex. But maybe that's silly.

amueller · 2016-02-17T00:10:55Z

I changed the naming scheme to x%d for easier visual parsing. I think x for data is good. We could also do x[%d], which is what we use in trees.

amueller · 2016-02-17T00:17:58Z

added a unicode test. Is that what you had in mind @jnothman ?

jnothman · 2016-02-17T01:43:42Z

sklearn/preprocessing/tests/test_data.py

+    # test some unicode
+    poly = PolynomialFeatures(degree=1, include_bias=True).fit(X)
+    feature_names = poly.get_feature_names([u"\u0001F40D", u"\u262E", u"\u05D0"])
+    assert_array_equal(["1", u"\u0001F40D^1", u"\u262E^1", u"\u05D0^1"],


It's a bit awkward that 1 is not unicode. Can we find a simple convention for such things?

jnothman · 2016-02-17T01:44:47Z

We could also do x[%d], which is what we use in trees.

That consistency (I assume you mean with visualisation) might be worthwhile, though I know that the use of the first subscript (as opposed to X[:, %d]) confuses people, despite the lowercase x.

amueller · 2016-02-19T19:56:18Z

hm, I can't reproduce the error... it seems to be in powers_. Weird.

amueller · 2016-02-19T20:49:45Z

powers_ is never tested and is broken in numpy 0.16.1 (fixed in 0.16.2), because it used the bincount of an empty sequence

amueller · 2016-02-19T20:56:43Z

should be fixed. I have no opinion re x[0] vs x0, The second has less "noise" I guess?

jakevdp · 2016-02-20T02:43:37Z

I would prefer x0 vs x[0], because it's half the number of characters and leads to easier-to-read variable names.

amueller · 2016-02-22T18:50:13Z

appveyor failure due to #4914.
@jakevdp @jnothman +1?

jakevdp · 2016-02-22T22:49:20Z

+1 for merge

jnothman · 2016-02-23T00:04:12Z

+1

yenchenlin · 2016-02-23T11:56:54Z

sklearn/preprocessing/data.py

+
+        Returns
+        -------
+        output_feature_names : list of string, length n_output_features


Just a nitpick here:
Maybe there should be a "." in the end of this line?

conventionally not.

Oh I see.
So this line:
https://github.com/amueller/scikit-learn/blob/poly_feature_names/sklearn/preprocessing/data.py#L1586
ends with a "." because it's a new sentence used to describe output?

Yes, it is description, not type.

amueller · 2016-02-24T22:08:30Z

should be good now.

jakevdp · 2016-02-24T22:10:30Z

Once tests pass I'd say we can merge

jakevdp · 2016-02-25T19:54:56Z

Thanks @amueller!

[MRG+2] add get_feature_names to PolynomialFeatures

amueller force-pushed the poly_feature_names branch from 48eb9e7 to 30e591e Compare February 16, 2016 21:17

jnothman reviewed Feb 16, 2016
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jakevdp reviewed Feb 16, 2016
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amueller force-pushed the poly_feature_names branch from 30e591e to ec4d92d Compare February 17, 2016 00:09

amueller force-pushed the poly_feature_names branch from ec4d92d to bff115c Compare February 17, 2016 00:17

jnothman reviewed Feb 17, 2016
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maniteja123 mentioned this pull request Feb 17, 2016

ENH: Add feature_names_ property to PolynomialFeatures #6216

Closed

amueller added 2 commits February 19, 2016 15:52

add get_feature_names to PolynomialFeatures

3fa684d

fix PolynomialFeatures.powers_ in python 0.16.1

ddc1740

amueller force-pushed the poly_feature_names branch from bff115c to ddc1740 Compare February 19, 2016 20:53

don't do ^1

897f8b6

amueller force-pushed the poly_feature_names branch from 9a11f46 to 897f8b6 Compare February 22, 2016 20:09

jnothman mentioned this pull request Feb 22, 2016

Pipeline object does not have a get_feature_names method - intentional? #6421

Closed

jnothman changed the title ~~[MRG] add get_feature_names to PolynomialFeatures~~ [MRG+2] add get_feature_names to PolynomialFeatures Feb 23, 2016

This was referenced Feb 23, 2016

RFC generalised Pipeline.get_feature_names #6424

Closed

Transformative get_feature_names for various transformers #6425

Closed

yenchenlin reviewed Feb 23, 2016
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fixed doc for powers, added test

8fb928d

jakevdp added a commit that referenced this pull request Feb 25, 2016

Merge pull request #6372 from amueller/poly_feature_names

7895d38

[MRG+2] add get_feature_names to PolynomialFeatures

jakevdp merged commit 7895d38 into scikit-learn:master Feb 25, 2016

amueller deleted the poly_feature_names branch May 19, 2017 20:24

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[MRG+2] add get_feature_names to PolynomialFeatures #6372

[MRG+2] add get_feature_names to PolynomialFeatures #6372

amueller commented Feb 16, 2016

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[MRG+2] add get_feature_names to PolynomialFeatures #6372

[MRG+2] add get_feature_names to PolynomialFeatures #6372

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