<div dir="ltr"><div>Hi Richard,</div><div><br></div><div>First, mesh layer time step is
not supposed to be constant. Some dataset could have variable time
steps, so there is not ONE time step available for each mesh layer or
dataset group.</div><div><br></div><div>If you need one time step, you can deduced if by using one of these ways:</div><div>- QgsMeshLayer::datasetMetadata()
that will return the metadata of the dataset, this metadata contains
the method time() that will return the time of the dataset in hours from
the reference time</div><div>- QgsMeshLayer::datasetRelativeTime() that will return a QgsInteval that is the time of the dataset from the reference time</div><div>- QgsMeshLayer::datasetRelativeTimeInMilliseconds(), same but return in milliseconds.</div><div></div><div><br></div><div>By soustraction of two dataset, you will have a time step, and if your data has constant time step it will be THE time step.</div><div>The reference time is not needed in your case but it can be obtained through the meta data of the dataset group.<br></div><div><br></div><div>Or
you can also use your method with the temporalCapabilities that should
give the same results, but it is more related to the data provider, and I
would avoid using it as it could have some issues with dataset group
indexes. <br></div><div><br></div><div>Note that the temporalUnit() of
the temporal capabilities is not the unit of the time returned by the
layer, but it the the data provider must considerer to read the times
value. Default is hour for MDAL, but in certain case, when MDAL can't
know the time unit, the user specify this unit. <br></div><div><br></div><div>Hope this helps.</div><div><br></div><div>Regards.</div><font color="#888888"><div><br></div><div>Vincent</div></font></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">Le mer. 8 mars 2023 à 10:42, Richard Duivenvoorde via QGIS-User <<a href="mailto:qgis-user@lists.osgeo.org">qgis-user@lists.osgeo.org</a>> a écrit :<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Ok, found it. It is in the temporalCapabilities...<br>
<br>
So given a loaded netcdf/mesh with time.<br>
Easiest is the firstTimeStepDuration(i) of QgsMeshDataProviderTemporalCapabilities:<br>
<br>
>>> p = iface.activeLayer().dataProvider().temporalCapabilities()<br>
>>> p<br>
<qgis._core.QgsMeshDataProviderTemporalCapabilities object at 0x7fa958267e20><br>
>>> p.timeExtent()<br>
<QgsDateTimeRange:[2022-11-07T07:00:00Z, 2022-11-08T06:00:00Z]><br>
>>> p.temporalUnit()<br>
<TemporalUnit.Hours: 3> <<< ?????<br>
# datasetTime() Returns the relative time in milliseconds of the dataset<br>
>>> p.datasetTime(QgsMeshDatasetIndex(0,0))<br>
3600000<br>
>>> p.datasetTime(QgsMeshDatasetIndex(0,1))<br>
7200000<br>
>>> p.datasetTime(QgsMeshDatasetIndex(0,2))<br>
10800000<br>
# firstTimeStepDuration() Returns the duration of the first time step of the dataset group with index \a group<br>
# in milliseconds<br>
p.firstTimeStepDuration(0)<br>
3600000 == 3600 s = 1 hours<br>
p.firstTimeStepDuration(0)<br>
21600000 == 21600 s == 360 minute == 6 hours<br>
<br>
Only strange thing is that the temporalUnit() always returns 'hours', while the actual data time is relative in minutes...<br>
<br>
Regards,<br>
<br>
Richard Duivenvoorde<br>
<br>
On 3/8/23 10:46, Richard Duivenvoorde via QGIS-User wrote:<br>
> Hi,<br>
> <br>
> (trying here too, sorry for cross posting)<br>
> <br>
> When loading (temporal) Netcdf files (as MeshLayers), the 'timestep'<br>
> that you see in the Temporal Controller does not change.<br>
> <br>
> I had a look at the api, but could not find any indication of knowledge<br>
> by the QgsMeshLayer of the size of the timesteps of the data.<br>
> <br>
> Within netcdf's it is common to define the timesteps as something like:<br>
> "minutes since 2022-11-27 16:00:00.0Z"<br>
> then the first set has 0, and then the next one for example 60 for<br>
> hourly data or 10 for 10-minute data.<br>
> <br>
> Question: IS a temporal mesh layer aware of the timesteps used?<br>
> <br>
> Or if not: I seem not to be able to inspect the data array of the 'time'<br>
> dimension. Should/can I?<br>
> <br>
> IF so, we could we could deduct from the first 2 or 3 timesteps, the<br>
> size of the timestep.<br>
> <br>
> Anybody a hint or idea?<br>
> <br>
> Regards,<br>
> <br>
> Richard Duivenvoorde<br>
> <br>
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