OK, I have been rereading the scoring codebase (which it becoming
frighteningly complicated), and it seems that the reason that we really
need this check is that the scores can multipled by "-1".
Maybe we should have a "try/except" where the multiplication happens, and
raise a meaningful error only if that multiplication fails.
I still haven't managed to fit this codebase in my head right, so I am
not sure how viable my suggestion would be. Anyhow, this is why we need
this check.
Gaël
On Mon, Feb 03, 2014 at 11:55:17AM -0800, Faraz Mirzaei wrote:
> Thanks Andy. I'll wait for your input (and will check the bug reports myself
> as
> well), before creating a new PR.
> In the mean time, I wonder why you would even need to do a type checking here?
> As far as I know, Python strongly encourages duck typing. Why not remove the
> type checking altogether and just let the exception "bubble up" when the duck
> cannot quack (i.e., when the score function output cannot be used by the
> respective caller)?
> As for cross_val_score being used in GridSearchCV, I quickly skimmed through
> the code and it doesn't look like it's being used there. Can someone else
> confirm as well?
> Thanks!
> Faraz
> On Sun, Feb 2, 2014 at 1:38 PM, Andy <t3k...@gmail.com> wrote:
> On 01/31/2014 09:50 AM, Gael Varoquaux wrote:
> >> if not isinstance(score, numbers.Number):
> >> raise ValueError("scoring must return a number, got %s (%s)"
> >> " instead." % (str(score), type(score)))
> > I am not opposed to making this check more relaxed: we could add an 'or
> > (isinstance(score, np.ndarray) and score.dtype.kind in ('i', 'f'))'.
> > PR welcomed
> > G
> This has come up before. I am not 100% what the trouble was. I put this
> in there as a bug fix.
> There was a PR, not sure where it went.
> cross_val_score is not called by GridSearchCV, right?
> I'll try to find out what I was thinking....
> Andy
>
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