Re: [ferret_users] z range (z=zz:zzz) doesn't limit the plotting within the range

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

Hi,
Yes, there are a number of subtle things about grids and regions in Ferret.  Generally the mindset is about working with the data as if it spans the grid cells. For instance an average of a variable over z=0:900 would include a contribution from a partial grid box up to the value of 900.

A mask like you suggest would definitely do the job.  Here's another way to define it, using the 'event' transformation.


  yes? let zcoords = z[gz=var]
  yes? let zmask = if zcoords[z=@EVNT:900] eq 0 then 1

On 3/6/2018 7:45 PM, Ryo Furue wrote:

Hi Ansley,

Thank you, thank you.

On Wed, Mar 7, 2018 at 2:43 AM, Ansley C. Manke <ansley.b.manke@xxxxxxxx> wrote:

The VECTOR/Y= /Z=  qualifiers are used to choose the subset of the data that will be sent to the plotting command. With this dataset, the coordinate value of the grid box that contains z=900 is 915.4, so the subset of data that you've requested includes data at z=289, 320, ..., 915.4. 

I'm surprised!   So, the Z= qualifier and the range like VAR[Z=0:900] choose the gridpoints by the grid boxes!  I thought the range chooses the gridpoints within the range.

That is subtle.

What's the most general way to choose gridpoints within the range.  Perhaps

   let var_new = if z[gz=var] ge 0  and z[gz=var] le 900 then var

?

Regards,

Ryo