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.g.johns...@gmail.com> wrote: > On Mon, Sep 14, 2015 at 2:55 PM, Biswadeep Banerjee < > biswadeep.baner...@actifio.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. > > >
