Re: incorrect plotting of polymarkers

On Nov 26, 2012, at 3:05 PM, Kantave Greene wrote:

> Hi Mary
> I tried executing what you suggested but it returns, " Loop end must be
> scalar, can't execute loop"

Hi Kantave,

My apologies, there's an error in the code I sent you. I should have used "lat" and "lon" and not "lat2d" and "lon2d". The "lat" and "lon" are what you read off the GRB file.

Also, you already had nlat set, so remove the line:

>> nlat = dimsizes(lat)

which is wrong anyway.

> I am assuming:
> 1. that lat2d /lon2d are the variables to which grb lat/lon are read into?

Yes, but I had typed the variable names wrong. You called them "lat" and "lon".

> 2. lat_pts/lon_pts are new arrays of size nlat?

Yes, the "new" command creates new arrays given a size and a type.

But I had that wrong (not my greatest day, yesterday!) They were
supposed to be arrays of the same size as lat_s and lon_s, because
these are the lat/lon values you want to plot the closest locations of:

npts = dimsizes(lat_s) ; should be 9
lat_pts = new(npts,typeof(lat_s))
lon_pts = new(npts,typeof(lon_s))

> 3. lat_pts(k) and lon_pts(k) are 1D arrays of indices?

No, lat_pts and lon_pts are 1D arrays of lat/lon values. You must pass lat/lon values
to gsn_add_polymarker, not indexes.

You used "getind_latlon2d" to get the index values of the lat/lon locations that were closest to some set of desired lat/lon values (lat_s/lon_s):

nm = getind_latlon2d (lat,lon, lat_s, lon_s)

nm is now a 2D array dimensioned 9 x 2, where you had 9 values in lat_s/lon_s, and the 2nd (rightmost) dimension gives you your lat /lon indexes.

I then used the nm array to collect the 9 lat/lon pairs, and put them into 1D arrays called lat_pts and lon_pts. This is what you should pass to gsn_add_polymarker.

--Mary

> Based on the script i submitted I was plotting an array of lat/lon
> indices called lat_markers and lon_markers which were derived from the
> loop/ function getind_latlon2d.
> Are you saying that the way I was associating the indices to the lat/lon
> was incorrect and that is why I should use the loop you provided?
>
> On 11/26/2012 3:25 PM, Mary Haley wrote:
>> I think you want to do this:
>>
>> nlat = dimsizes(lat)
>> lat_pts = new(nlat,typeof(lat2d))
>> lon_pts = new(nlat,typeof(lon2d))
>> do k=0,nlat-1
>> n = nm(k,0)
>> m = nm(k,1)
>> lat_pts(k) = lat2d(n,m)
>> lon_pts(k) = lon2d(n,m)
>> end do
>>
>> dum = gsn_add_polymarker(wks,map,lon_pts,lat_pts, mres)
>>
>>
>> On Nov 26, 2012, at 10:57 AM, Kantave Greene wrote:
>>
>>> Hello
>>>> I am having a problem with polymarkers being plotting incorrectly on a lambert conformal map although there indices are valid and correct. The attached image is the output from the script.
>>>> Based on the user specified lat/lon, getind_latlon2d returns the indices which polymarker then plots. Using the following statement:
>>>> print(n+" "+m+" "+lat(n,m)+" "+lon(n,m))
>>>> I confirmed that the indices are returning the nearest lat/lon to the indices.
>>>> Can you help me get the script to plot the indices correctly?
>>>>
>>>> Please find attached a copy of the code and output file I am using. Thanks for all your help.
>>>>
>>> --
>>> Kantave Greene
>>> Instructor
>>> Meteorology Department
>>> Jackson State University
>>> P.O. Box 17660
>>> Jackson, MS 39217
>>> (601) 979-1293
>>>
>>> <plot_polygon.ncl><polygon_orig.ps>_______________________________________________
>>> ncl-talk mailing list
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>>
>
> --
> Kantave Greene
> Instructor
> Meteorology Department
> Jackson State University
> P.O. Box 17660
> Jackson, MS 39217
> (601) 979-1293
>
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> ncl-talk mailing list
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Received on Tue Nov 27 09:30:22 2012