[ncl-talk] Error number dimensions ttest funcion

[Adam Phillips]

Hi Noelia,
sX and sY should be the sample sizes, so I think you should change these
lines:
sX   = dimsizes (ave_ua_ncep)
sY = dimsizes(ave_ua_model)
to these lines:
sX   = dimsizes (ave_ua_ncep&time)
sY = dimsizes(ave_ua_model&time)

Alternatively, you could use the equiv_sample_size function:
https://www.ncl.ucar.edu/Document/Functions/Built-in/equiv_sample_size.shtml

If you have any further queries please respond only to the ncl-talk list.
Adam

On Wed, Nov 19, 2014 at 1:11 PM, Noelia otero <noeli1680 at gmail.com> wrote:

> Hi,
>
> I am having problems with the ttest function, the error is:
>
> fatal:ttest: If s1 is not a scalar, then it must have the same number of
> dimensions as ave1, var1, ave2, and var2
>
> I don't understand very much this error, I would like to ask you what I am
> missing here.
>
> This is a piece of the code:
>         ua_ncep = u_ncep->uwnd(1:42,1,:,:) ;select 925 level
>         ;Averages
>         ave_ua_ncep=dim_avg(ua_ncep(lat|:,lon|:,time|:))
>         ;Variances
>         Var_ua_ncep = dim_variance (ua_ncep(lat|:,lon|:,time|:))         ;
> calculate variances
>         ;Defining sizes
>         sX   = dimsizes (ave_ua_ncep)
>         ;Model
>         ua_model = uFiles[i]->ua(1:42,1,:,:)  ;plevel 1=925 plevel 9=200
>         ;Time averages
>         ave_ua_model=dim_avg(ua_model(lat|:,lon|:,time|:))
>         ;Variances
>         Var_ua_model = dim_variance (ua_model(lat|:,lon|:,time|:))    ;
> calculate   var.
>         sY=dimsizes(ave_ua_model)
>         iflag=False
>         ;Significance levels:
>    prob = ttest(ave_ua_ncep,Var_ua_ncep^2,sX,
> ave_ua_model,Var_ua_model^2,sY, iflag, False) ;using STD
>
> I also wanted to ask you, in this case, would it be necessary to use
> wgt_areaave
> <https://www.ncl.ucar.edu/Document/Functions/Built-in/wgt_areaave.shtml>?
>
> Many thanks in advance,
>
>
> Cheers,
>
>
> Noelia
>
>
>
>
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-- 
Adam Phillips
Associate Scientist,  Climate and Global Dynamics Division, NCAR
www.cgd.ucar.edu/staff/asphilli/   303-497-1726

<http://www.cgd.ucar.edu/staff/asphilli>
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