h5md-user
[Top][All Lists]

## Re: [h5md-user] proposal 100 - update

 From: Felix Höfling Subject: Re: [h5md-user] proposal 100 - update Date: Tue, 16 Jun 2015 11:13:16 +0200 User-agent: Opera Mail/12.16 (Linux)

```
```
```Hi all,

On Mon, Jun 01, 2015 at 10:01:06PM +0200, Pierre de Buyl wrote:
```
```On Mon, Jun 01, 2015 at 03:54:16PM -0400, Peter Colberg wrote:
> On Fri, May 29, 2015 at 08:46:56AM +0200, Pierre de Buyl wrote:
```
> > But, in another likely usage, imagine that step is not linear and that
```> > time[i]=step[i]*DT for all values of i.
> >
```
> > My "new" extension is that if you have a non-scalar dataset for "step" and a
```> > scalar dataset for "time", you can compute the value in time as
> > time[i]=step[i]*time
>
> If time depends on step, I would suggest this scheme:
>
>   \-- step[Inf]
>   |    +-- timestep: Float[]
>   \-- value[Inf, …]
>
> However, to keep things simple, I would not favour this extension. If
> one already goes through the trouble of writing the variable-length
> step dataset, it is not much more work to write the time dataset using
> the same datatype and dataspace.

```
It is more about writing less data than convenience per se. I don't see this as
```a "must have" though.
```
```
Any other opinion on this?

```
As a reminder, I propose that step[Inf] and time[] (that is, a scalar dataset) allows one to evaluate the time at index i as (step[i]+step.offset*time[]).
```
P

```
```
I think the correct formula reads:
time[i] = time.offset + (step[i] - step.offset) * time[]

```
The benefit of such an extension to the proposal is really small, so I would drop it. I think that most situations are covered by the following to scenarios:
```
```
i) for "rare" sampling (only at a few steps) it is most straightforward to write step and time explicitly, as it is in 1.0.
```
```
ii) for more frequent, regular sampling, the proposal offers the calculation of the sampling time from the array index, the increment (scalar dataset "time") and the offset (attribute time.offset)
```
Pierre, is their a specific application which motivates your suggestion?

Felix

```