Re: [ferret_users] How to grab time info?

2011/3/18 Ansley Manke <Ansley.B.Manke@xxxxxxxx>

Hi -
You can assign a time to a variable that has no time axis by adding a variable with value zero defined at that time. Using your one-point time axis,

define axis/t="`t[g=swh,l=$1],return=tend`":"`t[g=swh,l=$1],return=tend`":1 time
let timestamp = 0* t[gt=time]

let var_with_time = var + timestamp

Ansley

On 3/18/2011 7:49 AM, Szymon Roziewski wrote:
Dear Hein,
Thank you for your help.
I tried out your solution but it doesn't work. I mean this chunk of code
let swh_smooth_with_time = swh_smooth[gt=swh]
this one works fine
`t[g=swh,l=$1],return=tend`

I would expect the time information to still be here when you do
"list swh". Is that correct?

this time information are stuck there (in swh).

I tried this approach by defining a new grid with time axis but it also doesn't work which looks odd for me.

let swh_smooth_t = scat2gridgauss_xy(xp[i=1:`npts`],yp[i=1:`npts`],dp[i=1:`npts`],x[g=grid_xfine_yfine],y[g=grid_xfine_yfine],xscale,yscale,cutoff,0)

define axis/t="`t[g=swh,l=$1],return=tend`":"`t[g=swh,l=$1],return=tend`":1 time
DEFINE AXIS/X=-5.666666667:5.25:0.010416667/unit=degree xfine
DEFINE AXIS/Y=-2.0:10.0:0.010416667/unit=degree yfine !1/8
DEFINE GRID/x=xfine/y=yfine/t=time grid_xfine_yfine1

let swh_smooth = swh_smooth_t[gxy=grid_xfine_yfine1,gt=time]

and also I checked

let swh_smooth = swh_smooth_t[gxyt=grid_xfine_yfine1]

Then I tested

define axis/t="`t[g=swh,l=$1],return=tend`":"`t[g=swh,l=$1],return=tend`":1 time2
let swh_smooth = swh_smooth_t[gt=time2]

which also doesn't work.

But I worked around this problem by that chunk of code as dr Hein wrote

let label_time = SUBSTRING("`t[g=swh,l=$1],return=tend`",0,17)
LABEL/NOUSER 1.1 `($ppl$ylen)+0.5` 0 0 .14 `label_time`

But I have no idea what to try out in case of changing time axis or grid.

If someone would like to have a look at this file it is in address: http://153.19.141.166/wam_2011031800.nc.tar.bz2 .

and needed part of script

DEFINE AXIS/X=-5.666666667:5.25:0.083333333/unit=degree xlon;\
DEFINE AXIS/Y=-2.0:10.0:0.083333333/unit=degree ylat;\
DEFINE GRID/x=xlon/y=ylat grid_xlon_xlat;\
DEFINE AXIS/X=-5.666666667:5.25:0.010416667/unit=degree xfine;\
DEFINE AXIS/Y=-2.0:10.0:0.010416667/unit=degree yfine !1/8;\
DEFINE GRID/x=xfine/y=yfine grid_xfine_yfine;\

let hstmp = hs[d=4]
let swh = hstmp[i=1:132,j=1:145,k=0,l=$1]
let xpts = xsequence(0*swh+x[g=swh])
let ypts = xsequence(0*swh+y[g=swh])
let datapts = xsequence(swh)
let xscale=0.1
let yscale=0.1
let cutoff=2
let xp = compressi(xpts)
let yp = compressi(ypts)
let dp = compressi(datapts)
let npts = dp[i=@ngd]
let swh_smooth_t = scat2gridgauss_xy(xp[i=1:`npts`],yp[i=1:`npts`],dp[i=1:`npts`],x[g=grid_xfine_yfine],y[g=grid_xfine_yfine],xscale,yscale,cutoff,0)

kind regards,
Szymon Roziewski

2011/3/17 Hein Zelle <hein.zelle@xxxxxxxxxxxxx>

Hi Szymon,

> How can I grab the time label e.g. when I do the command
> let swh = hstmp[i=1:132,j=1:145,k=0,l=$1] I loose information about the time
> (i.e. 16-Jan-2011 01:00)

I would expect the time information to still be here when you do
"list swh". Is that correct?

> and then when I smooth
> let swh_smooth =
> scat2gridgauss_xy(xp[i=1:`npts`],yp[i=1:`npts`],dp[i=1:`npts`],x[g=grid_xfine_yfine],y[g=grid_xfine_yfine],xscale,yscale,cutoff,0)
> set var/title = "Significant Wave Height [m]" swh_smooth

You've removed the time information here, because you're not defining a
grid with a time axis for the new variable. Try re-assigning a time
axis to variable swh_smooth, for example

let swh_smooth_with_time = swh_smooth[gt=swh]

You may have to define a new time axis with only 1 time step.
Alternatively, to plot a label you can use

`t[g=swh,l=$1],return=tend`

which gives you the formatted date/time string.

Kind regards,
Hein

--

Dr. Hein Zelle
Advisor Meteorology & Oceanography

Tel: +31 (0)527-242299
Fax: +31 (0)527-242016
Email: hein.zelle@xxxxxxxxxxxxx
Web: www.bmtargoss.com

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Z wyrazami szacunku,
Szymon Roziewski