Re: Built-in binning functions

On 16 July 2014 20:35, Pavel Stehule <pavel.stehule@gmail.com> wrote:
>
>
>
> 2014-07-16 10:04 GMT+02:00 Petr Jelinek <petr@2ndquadrant.com>:
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>> On 08/07/14 02:14, Tom Lane wrote:
>>>
>>> Petr Jelinek <petr@2ndquadrant.com> writes:
>>>>
>>>> here is a patch implementing varwidth_bucket (naming is up for
>>>> discussion) function which does binning with variable bucket width.
>>>
>>>
>>> I didn't see any discussion of the naming question in this thread.
>>> I'd like to propose that it should be just "width_bucket()"; we can
>>> easily determine which function is meant, considering that the
>>> SQL-spec variants don't take arrays and don't even have the same
>>> number of actual arguments.
>>
>>
>> I did mention in submission that the names are up for discussion, I am all
>> for naming it just width_bucket.
>
>
> I had this idea too - but I am not sure if it is good idea. A distance
> between ANSI SQL with_bucket and our enhancing is larger than in our
> implementation of "median" for example.
>
> I can live with both names, but current name I prefer.

Hmmm, not sure. Let's look around and think what words people use.

Transforms of this type are referred to as discretization in formal
literature and as binning in commong usage/statistical software.

width_bucket() seems to refer to an equal-width binning process. The
function being discussed here is a generic mechanism, the boundaries
of which could have been decided using equal-frequency or other
mechanisms. Using the word "width" in those contexts could be
confusing.

Given width_bucket() is already in use for SQL Standard function, I
agree it would be confusing to have same name for different parameter
profiles.

So I suggest that we use the more generic function name bin(), with a
second choice of discretize()  (though that seems annoyingly easy to
spell incorrectly)

Whatever we do, it seems clear we need a section in the manual to
describe Statistical Functions, including width_bucket(), whatever we
call this function and including the terms bin, binning, transform,
discretize and discretization to ensure those are easily searchable.

-- Simon Riggs                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services