From: Mary Haley <haley_at_nyahnyahspammersnyahnyah>

Date: Mon Apr 04 2011 - 08:24:59 MDT

Date: Mon Apr 04 2011 - 08:24:59 MDT

On Apr 1, 2011, at 10:26 AM, H.Dang wrote:

*> Hi Mary,
*

*>
*

*> Thanks for your kind explanation. So my current understanding is that "gsn_csm_xy (wks,ts&time,data,res)" is to plot 2 sets of data. :
*

*>
*

*> 1. ts vs. data(0,:)
*

*> 2. ts vs. data(1,:)
*

It's more like:

data(0,:) vs ts&time

data(1,:) vs ts&time

"data" is for the Y axis, and ts&time is the X axis. It's not plotting "ts", but the time coordinates associated with "ts".

What you are seeing in this figure is correct. If you were to print the ts&time values, you would see they go from 6113 to 9125, and this is what you see on the X axis.

The data(0,:) values go from 268.0111 to 271.0618, and the data(1,:) values (the line) go from 268.4577 to 270.5234.

The "x" array was simply used as input to "regline", which caculates the regression coefficient.

--Mary

*>
*

*> Based on http://www.ncl.ucar.edu/Applications/Scripts/scatter_4.ncl,
*

*>
*

*> x = ispan(0,dimsizes(ts)-1,1)*1.
*

*> ...
*

*> data(0,:) = ts
*

*> data(1,:) = rc*(x-rc@xave) + rc@yave
*

*> ...
*

*> res@xyMarkLineModes = (/"Markers","Lines"/) ; choose which have markers
*

*> ...
*

*> plot = gsn_csm_xy (wks,ts&time,data,res) ; create plot
*

*> end
*

*>
*

*> It firtly plots "ts vs data(0,:)=ts", which should be a line with slope 1. Then it will plot "ts vs data(1,:)=regression line". In both cases, ts is the x-axes, but this code corresponds to the figure http://www.ncl.ucar.edu/Applications/Images/scatter_4_lg.png
*

*>
*

*> Since this figure's x-axes is "time", I don't understand why the code is not like:
*

*>
*

*> plot = gsn_csm_xy (wks,x,data,res)
*

*>
*

*>
*

*> Cheers
*

*> Hongyan
*

*> On Fri, Apr 1, 2011 at 10:13 AM, Mary Haley <haley@ucar.edu> wrote:
*

*> On Mar 31, 2011, at 5:06 PM, H.Dang wrote:
*

*>
*

*>> Hi dear all,
*

*>>
*

*>> I have a question regarding a scatter plot example on NCL website:
*

*>>
*

*>> http://www.ncl.ucar.edu/Applications/Scripts/scatter_4.ncl
*

*>>
*

*>> The last 2 lines are:
*

*>>
*

*>> plot = gsn_csm_xy (wks,ts&time,data,res) ; create plot
*

*>> end
*

*>>
*

*>> The "&time" doesn't work in my NCL, but I can get plots simply use:
*

*>>
*

*>> plot = gsn_csm_xy (wks,ts,data,res) ; create plot
*

*>> end
*

*>>
*

*>> I'm not sure if it's okay if I do it this way.
*

*>
*

*> Dear Hongyan,
*

*>
*

*> It's okay to put "ts" there, as long as the dimensions of ts and data are correct, and that this is what you actually want to plot.
*

*> This call will simply put the "ts" values on your X axis and the "data" values on your Y axis.
*

*>
*

*>
*

*>> And is the x-axes is the pre-defined "x"?
*

*>>
*

*>> x = ispan(0,dimsizes(ts)-1,1)*1.
*

*>
*

*>
*

*> No, it should be set to the values of "ts". That is, the X values will span min(ts) to max(ts).
*

*>
*

*> If you had used:
*

*>
*

*> plot = gsn_csm_y(wks,data,res) ; Note, no "ts"
*

*>
*

*> Then "data" would be on your Y axis, and the x axis would be the "ispan" values as you defined above.
*

*>
*

*> --Mary
*

*>
*

*>>
*

*>> Thank you.
*

*>> --
*

*>> Cordially,
*

*>> Hongyan(ΊθΡγ)
*

*>> Tel: 1-519-8884567ext36667
*

*>>
*

*>>
*

*>> _______________________________________________
*

*>> ncl-talk mailing list
*

*>> List instructions, subscriber options, unsubscribe:
*

*>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
*

*>
*

*>
*

*>
*

*>
*

*> --
*

*> Cordially,
*

*> Hongyan(ΊθΡγ)
*

*> Tel: 1-519-8884567ext36667
*

*>
*

*>
*

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Received on Mon Apr 4 08:24:59 2011

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