Re: [BUGS] BUG #13619: regression functions return Null

Oops!! My bad.. I did a reply and not a reply all...

Anyways Thanks David.. I knew this wasn't really a bug but could not figure
out where to post my questions. Let me just try the same in a different way
or do it differently as you explained and see if I can make it to work.

Thanks

On Tue, Sep 15, 2015 at 12:33 AM, David G. Johnston <
david(dot)g(dot)johnston(at)gmail(dot)com> wrote:

> Oh, and don't reply to people individually. I'm going to move this to
> -general with one last copy for -bugs even though it is not one.
>
> On Mon, Sep 14, 2015 at 3:01 PM, David G. Johnston <
> david(dot)g(dot)johnston(at)gmail(dot)com> wrote:
>
>> On Mon, Sep 14, 2015 at 2:55 PM, Biswadeep Banerjee <
>> biswadeep(dot)banerjee(at)actifio(dot)com> wrote:
>>
>>> Hi David,
>>> May be I gave a wrong example to explain my issue.
>>>
>>> Below is a sample query that I have been trying to get the slope and
>>> intercept. The inner query basically gives me the time vs capacity, ie. x
>>> and y data showing the actuals. Based on the x, y value, I calculate slope
>>> and intercept value, as in the outer query.
>>>
>>> But it looks like am back to your comment as it mentions I am asking for
>>> slope and intercept of a single point. Could you provide me some examples
>>> that I can use as a reference.
>>> As a reference, I am following similar example as in
>>> http://stackoverflow.com/questions/20490756/linear-regression-with-postgres
>>>
>>> select x, y, regr_slope(y,x), regr_intercept(y,x)
>>> from (
>>> ​/* doesn't matter */
>>>
>>> ) i
>>> group by x, y
>>> order by x asc, y asc
>>>
>>
>> ​You are grouping on (x, y)​
>>
>> ​ and then passing this single POINT into a function that requires
>> multiple points in order to calculate the slope and intercept of a LINE
>> (i.e., something requiring two points to describe) and are confused why it
>> is giving you NULL...
>>
>> ​I have answered your question - you are using the functions incorrectly.
>>
>> This is operator error, not a bug.
>>
>> You have already found a reasonably good example of how these functions
>> can be used. Given I have never used them myself I do not have anything
>> better to offer.
>>
>> David J.
>> ​
>> ​
>>
>
>

--

Best Regards,
Biswadeep Banerjee