Re: [ferret_users] Interpolation problem

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

Hi,
I read your question more closely and my answer was too simplistic. Your 
data has a whole batch of data at a single date, lon, lat, time, depth, 
then another bath at the same date, lon, lat and a new depth. (It would 
be helpful to describe your data in the message in addition to including 
it). So I think that's what you are doing with this mask.

Note that the mask you defined has a value of 1 for many repeated values 
near the start of the list. If you want to get the locations where depth 
changes, just something like this will work:

let mask = if dep[ddf] NE 0 then 1

but perhaps you have something else in mind. Assuming the mask picks out 
non-repeating values of dep, then continuing after the definitions in 
your script, I would do this:

let masked_dep = dep*mask
let masked_tem = tem*mask
let masked_sa = sa*mask

! Compress gaps out of these variables
let depths = compressk(masked_dep)
let temp = compressk(masked_tem)
let salt = compressk(masked_sa)

! Number of vaid data in the variable
let nz = `depths[z=@ngd]`

! The data are on the depth axis defined by the depth variable in the data:
define axis/z/units=meters zaxis_in = depths[k=1:`nz`]

let salt_in = salt[gz=zaxis_in@ASN]
let temp_in = temp[gz=zaxis_in@ASN]

! now define the axis you want, with increments of 0.5 meters
! Instead of zmax as defined, you'll want that value, rounded up to the 
next 0.5 meters.

let zmax = `depths[z=@max]`  ! want to round this up to the nearest 0.5
define axis/z=0:`zmax`:0.5/units=meters z05

! Regrid the input data to that axis.
! These commands could have /UNITS= and /TITLE= to define 
self-documenting variables.
! You could choose a different regridding transformation, such as @AVE.

let salinity = salt_in[gz=z05]
let temperature = temp_in[gz=z05]

On 12/4/2012 2:17 AM, Akshay Hegde wrote:
> Hi ! experts...
>
> I am trying to interpolate my data file....
>
> pls have a look on data file...
>
>
> I need temperature and salinity value with a bin size of 0.5 meter..
>
>
> define axis/z=1:377:1 zax
> define grid/z=zax mygrid
> columns/skip=1/delim="\t,\b"/type="numeric,numeric,numeric,numeric,numeric,numeric,numeric"/grid=mygrid 
> ctd001_ins1_04-08-07_1100.out
>
> let date =v1
> let time =v2
> let lon =v3
> let lat =v4
> let dep = v5
> let tem = v6
> let sa = v7
>
> let mask = if dep[z=@ddf] eq dep[z=@ddb]  then 1
> list mask, dep,tem,sa
>
> till here I could able to do...how can I get temp, sal value with bin 
> size of 0.5
>
>
> Thanks in advance...
>
>
> Akshay