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Re: [ferret_users] time substitution question

Hi Ghansham,
This question was asked in another unrelated thread. It's always best to start new threads for each new topic. I thought I'd split it off into a new topic.

On 2/24/2014 5:40 PM, Ghansham Sangar wrote:

hi sir

thanks a lot for informative mail.
regarding substitution stuff, i gave a count variable like this
where timedim is 1 in size.
the data range of this variable is 0 to 1023. I have another variable TIR_TEMP which is 1 dimensional of size 1024. I want to use TIR dara values to index into TIR_TEMP values to create a TIR_TEMP 3d variable

I still don't know if I understand what you mean about indexing into another variable. Here are a couple of possibly related topics that may get you started.

1) You can define an axis from the data in a variable. If TIR_TEMP represents time in known units since some date, then this would looks like

   yes? define axis/t/t0="time string"/units="time units"  tax = TIR_TEMP

Then, if the time coordinate variable of your TIR[timedim][dimx][dimy] has the same time origin and units as the axis "tax", you can

   yes? let tir_on_tax = tir[gt=tax]

and the variable will be defined on axis "tax", with data only at that time step. This is a regridding operation, so you could choose any of the different regridding transformations.

2) Look up "conformability" in the Users Guide Index. This is about working with variables on different-dimensioned grids and combining them in an expression.

3) Have a look at the topic "timestamp". Do you want to start with a set of snapshots in XY, give each one a time stamp so that each becomes a timestep on a common T axis, and then assemble them into an XYT dataset?


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