[ncl-talk] Swapped x, y coordinates of shapefile?

[Rick Brownrigg]

Hi,

Yes, there have been reports of this with NCL v6.6.2 as distributed via
conda (does that describe your circumstances?)  I don't know the root cause
nor am I in a position to investigate. However, as a kludge, you can
certainly swap the shapefile's x/y coordinates in any of a number of ways,
perhaps something like:
     myShpFile = addfile(....)
     ...
     theActualXCoord = myShpFile->y   ; Swap X/Y to fix known bug...
     theActualYCoord = myShpFile->x

Hope that helps...
Rick

On Mon, Jan 25, 2021 at 3:30 PM Holman, Kathleen D via ncl-talk <
ncl-talk at mailman.ucar.edu> wrote:

> Hello,
>
> I am trying to use the shapefile_mask_data() function to mask
> precipitation data (time, lat, lon) using boundaries defined in a
> shapefile, subs_buff_mod.shp.  When I plot the shapefile in ArcGIS, the
> spatial extent appears correct (see screenshot).  This basin is in
> Colorado, so the latitude extent should be between 40 and 40.5 north, while
> the longitude extent should be between -106 and -105 east.  Unfortunately,
> the mask function continues to produce missing values, and I *think* the
> reason for this is because the x and y coordinates of the shapefile are
> getting swapped when I import the shapefile into NCL.  Here is a snippet of
> text from the print_shapefile_info() command.  The latitude and longitude
> ranges are swapped from what they should be for Colorado, but again, the
> shapefile properly plots in ArcGIS.  Can I swap the coordinates somehow?
> Any idea where this happening or how to remedy this?
>
> (0)
> ======================================================================
> (0)     Filename: "../GIS/subs_buff_mod.shp"
> (0)        Geometry type: polygon
> (0)        # of features: 8
> *(0)        Min/max lat:   -105.82/-105.45*
> *(0)        Min/max lon:     40.23/  40.50*
> (0)        Variable names and their types:
> (0)            geometry : integer
> (0)            segments : integer
> (0)            x : double
> (0)            y : double
> (0)            Shape_Leng : double
> (0)            Shape_Area : double
> (0)            HydroID : int64
> (0)            Name : string
> (0)            BUFF_DIST : double
> (0)            ORIG_FID : int64
> (0)
> ======================================================================
>
> Here are the min/max values of the latitude and longitude coordinates
> associated with the precipitation data.
>
> (0)     latitude (degrees_north) : min=36.532672   max=50.232124
> (0)
> (0)     longitude (degrees_east) : min=-114.7339440000123
> max=-90.00160000003234
>
>
>
>
> Thank you,
>
> Katie Holman, PhD
> Meteorologist
> Technical Service Center
> Bureau of Reclamation
> 303-445-2571
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