Re: [ferret_users] transect wrong direction of label

["Ansley C. Manke" <ansley.b.manke@xxxxxxxx>]

Hi Marco,

Is the axis originally defined with units of longitude? It might be 
enough to just redefine the axis, rather than defining a new axis and 
regridding:

   set axis/units=degrees_east translon

Then the axis should be defined as a modulo longitude axis, as long as 
the entire range of values is no more than 360 degrees, and the plots 
and other calculations, such as making expressions with other longitude 
axis, should work fine.

-Ansley

On 2/10/2017 8:49 AM, Marco van Hulten wrote:
> Hello,
>
> I am plotting a roughly zonal transect from ORCA2 gridded data.
> The x-coordinate is negative everywhere and monotonically increasing.
> When I do the plot, I get labels like
>
>      150°E  140°E  130°E
>
> but it should be
>
>      150°W  140°W  130°W
>
> or I would also settle for the equivalent
>
>     -150°E -140°E -130°E
>
>
> This is the setup:
>
> yes? list/i=1:3 TransLon,TransLat
>               X: 0.5 to 3.5
>   Column  2: TRANSLAT is TRANS_LAT[D=COORDS_GP16.CSV]
>         TRANSLON  TRANSLAT
> 1   / 1:  -152.0  -10.50
> 2   / 2:  -150.0  -10.25
> 3   / 3:  -147.5  -10.77
>
> yes? define axis/X/units=degrees_east MyAxis=TransLon
> yes? let TrOnTransect = Reshape( Tr_sampled, X[GX=MyAxis] + Z[GZ=Tr[d=1]] )
> yes? shade TrOnTransect
>
> I was able to replace E for W by using units=degrees_west, but I
> couldn't change it back: it would still display °W.  That is my goal,
> but the problem seems that axis definitions are sometimes persistent or
> something.  I can, e.g., also not cancel an axis when it is used by a
> grid.  Could that be the reason?
>
> Furthermore, I do not understand why MyAxis is always labeled with
> positive numbers, even though the TransLon elements are negative.
>
> Marco