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Re: [ferret_users] regression issue: one variable VS another variables

Hi David,
Sure, PLOT/VS/LINE  will just connect the dots in the order they appear in the variables, with no plot marker.
Instead of the last line in your example, substitute,

    yes? plot/vs/nolab/over/line p,qhat

Or, to be more accurate, if there's missing data, you want to plot p only where there are valid values of P and Q.  Look at the regression script

   yes? go/help regresst

and see that the variable pmasked is "p where p and q"

   yes? plot/vs/nolab/over/line pmasked,qhat


David Wang wrote:
Hi Yangxing,

Here is an example that you can reproduce:

yes? use "http://iridl.ldeo.columbia.edu/SOURCES/.Indices/.nino/.NCEP_OIv2/dods"
yes? sh d
     currently SET data sets:
    1> http://iridl.ldeo.columbia.edu/SOURCES/.Indices/.nino/.NCEP_OIv2/dods  (default)
 name     title                             I         J         K         L
 NINO12   NINO12                           ...       ...       ...       1:328
 NINO3    NINO3                            ...       ...       ...       1:328
 NINO34   NINO34                           ...       ...       ...       1:328
 NINO4    NINO4                            ...       ...       ...       1:328

yes? let p = nino3
yes? let q = nino34
yes? go regresst
yes? plot/vs p,q
yes? plot/vs/nolab/over/line/sym=dot p,qhat

OK, I admit it's not really a straight line, but a series of connected dots. Does anyone out there know if PLOT/VS can have no marker?


On Wed, Mar 18, 2009 at 1:19 PM, yangxing zheng <yangxingz@xxxxxxxxx> wrote:

 Thanks for help. But I am still not clear.

 My question is: sst, a function of time, is an independent variable. and u is a dependent variable, which is also a function of time. How can we make a line plot when u is regressed onto sst? Apparently sst as an independent variable is not originally monotonic, it has be reshaped, right?

 The FAQ indicates that regresst only describes how to regress a variable (a function of time) into the independent variable T, Am I right? For example, we can do regression sst vs T using regresst.jnl

 The attached figure is a scatter plot of u (in Y-coordinate) VS sst ( in X-coordinate). Can you explain more details for my case?


--- On Wed, 3/18/09, David Wang <climater@xxxxxxxxx> wrote:

> From: David Wang <climater@xxxxxxxxx>
> Subject: Re: [ferret_users] regression issue: one variable VS another variables
> To: "yangxing zheng" <yangxingz@xxxxxxxxx>
> Cc: ferret_users@xxxxxxxx
> Date: Wednesday, March 18, 2009, 8:29 AM
> Hi Yangxing,
> regresst.jnl is what you need. Please follow this FAQ:
> http://ferret.pmel.noaa.gov/FERRET_17sep07/FAQ/analysis/regressions.html
> It's the least square fit.
> HTH,
> D.
> On Tue, Mar 17, 2009 at 7:56 PM, yangxing zheng
> <yangxingz@xxxxxxxxx> wrote:
> > Hi,
> >
> >  I do have two variables like area averaged sst, and u
> (zonal winds) from l
> > = 1:100 (for simple case, sst and u only has one
> dimension of time)
> >
> >  we can make scatter plot
> >  plot/vs sst,u
> >
> >  Now I want to see how sensitive of u to sst, we
> usually plot a line that
> > describe the relationship between u and sst. How can
> we make it in ferret?
> >
> >  Attached is one example of scatter plot.
> >
> >   Thanks.
> >
> >   yx
> >
> >
> >
> --
> life grows, death doesn't. there is no dress rehearsal.


life grows, death doesn't. there is no dress rehearsal.

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