# Re: Dimensionality problem

From: Dennis Shea <shea_at_nyahnyahspammersnyahnyah>
Date: Thu Jul 07 2011 - 13:25:26 MDT

What do you mean by "unrealistic values" ?

No 'do loop'

I think you want is
wt = water(latitude|:,longitude|:,time|:)
rc = regCoef(x, wt )
print("rc: min="+min(rc)+" max="+max(rc) )

If the grid is rectilinear, add the following

rc!0 = "latitude" ; name dimensions
rc!1 = "longitude"
rc&latitude = water&latitude ; assign coordinate values
; to named dimensions
rc&longitude = water&longitude

rc@long_name = "regression coef"
printVarSummary(rc)

On 7/7/11 12:42 PM, Lizz Ultee wrote:
> Hi NCL-Talk,
> I have emailed with a related problem before, but I hope you will be able
> to help me with this. I was debating between regCoef and regline for a
> particular application; regline gives errors but regCoef returns
> unrealistic values. What I want to do is get a linear trend on some data
> that has dimensions time, latitude, and longitude--I only want the trend
> as it relates to time (getting secular trend of seasonally varying data).
> The relevant section of code is:
>
> water = in->water
> lat=in->latitude
> lat@units="degrees_north"
> lon=in->longitude
> lon@units="degrees_east"
> time=in->time
> wt = water(latitude|:,longitude|:,time|:) ; reorder
> variable
> ;************************************************
> ; create x and calculate the regression coefficient
> ; note regline works on one dimensional arrays.
> ;************************************************
> ; x = ispan(0,dimsizes(wt&time)-1,1)*1. ; I have this
> commented out currently, can be
> ;
> used
> only
> if
> wt
> is
> defined
> beforehand
> x = ispan(0, 381, 1)*1. ; the time dimension
> is of size 382 so this is equiv
>
> do latitude=-59.5, 89.5, 1
> do longitude=-179.5,179.5, 1
> ; wt = water(latitude|:,longitude|:,time|:) ; reorder
> variable inside do-loop?
> rc = regline(x,wt)
> rc!0 = "latitude"
> ; trying to assign dimensionality to rc
> rc!1 = "longitude"
> end do
> end do
>
>
>
> The error I get is:
> fatal:Number of dimensions in parameter (1) of (regline) is (3), (1)
> dimensions were expected
>
> But to my mind, using a do-loop should plug in pairs of constants in wt
> and thus make it 1-dimensional. I would like to have values on a lat/lon
> grid. Thanks in advance for any suggestions!
>
> Best,
> Lizz Ultee
>
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Received on Thu Jul 7 13:25:31 2011

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