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On Wed, May 1, 2024 at 11: 03 PM Adrian Croucher <a. croucher@ auckland. ac. nz> wrote: hi Matt & all, I just had a query from one of my users which prompted me to see if any progress had been made on the issue below - using PETSc to get
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<div dir="ltr"><div dir="ltr">On Wed, May 1, 2024 at 11:03 PM Adrian Croucher <<a href="mailto:a.croucher@auckland.ac.nz">a.croucher@auckland.ac.nz</a>> wrote:<br></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><u></u>
<div>
<p>hi Matt & all,</p>
<p>I just had a query from one of my users which prompted me to see
if any progress had been made on the issue below - using PETSc to
get the number of time steps in an HDF5 file.</p>
<p>I can't see anything new in PETSc on this - I did try using
PetscViewerHDF5ReadSizes() to see if that would do it, but it
seems it doesn't. If I use that on the "time" dataset it just
returns 1.</p>
<p></p></div></blockquote><div>Sorry about the delay. I had lost track of this. Can you look at branch</div><div><br></div><div> knepley/feature-hdf5-seq-len</div><div><br></div><div>I have not made a test yet, but if this works for you, I will make a test and merge it in.</div><div><br></div><div> Thanks!</div><div><br></div><div> Matt <br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><p>Regards, Adrian<br>
</p>
<div>On 11/10/21 2:08 pm, Adrian Croucher
wrote:<br>
</div>
<blockquote type="cite">
<div>On 10/11/21 11:59 AM, Matthew Knepley
wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div dir="ltr">On Sun, Oct 10, 2021 at 6:51 PM Adrian Croucher
<<a href="mailto:a.croucher@auckland.ac.nz" target="_blank">a.croucher@auckland.ac.nz</a>>
wrote:<br>
</div>
<div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">hi<br>
<br>
Is there any way to query the PETSc HDF5 viewer to find
the number of <br>
time steps in the file?<br>
<br>
A common use case I have is that an HDF5 file from a
previous simulation <br>
is used to get initial conditions for a subsequent run.
The most common <br>
thing you want to do is restart from the last set of
results in the <br>
previous output. To do that you need to know how many time
steps there <br>
are, so you can set the output index to be the last one.<br>
<br>
I thought maybe I could just query the size of the "time"
dataset, but I <br>
can't even see any obvious way to do that using the viewer
functions.<br>
</blockquote>
<div><br>
</div>
<div>There is nothing in there that does it right now. Do
you know how to do it in HDF5?</div>
<div>If so, I can put it in. Otherwise, I will have to learn
more HDF5 :)</div>
</div>
</div>
</blockquote>
<br>
<p>I haven't actually tried this myself but it looks like what you
do is:</p>
<p>1) get the dataspace for the dataset (in our case the "time"
dataset):</p>
<p>hid_t dspace = H5Dget_space(dset);</p>
<p>2) Get the dimensions of the dataspace:<br>
</p>
<p>const int ndims = 1;<br>
</p>
<p>hsize_t dims[ndims];<br>
H5Sget_simple_extent_dims(dspace, dims, NULL);</p>
<p>The first element of dims should be the number of time steps.
Here I've assumed the number of dimensions of the time dataset
is 1. In general you can instead query the rank of the dataspace
using H5Sget_simple_extent_ndims() to get the rank ndims.</p>
<p>Regards, Adrian<br>
</p>
</blockquote>
<pre cols="72">--
Dr Adrian Croucher
Senior Research Fellow
Department of Engineering Science
Waipapa Taumata Rau / University of Auckland, New Zealand
email: <a href="mailto:a.croucher@auckland.ac.nz" target="_blank">a.croucher@auckland.ac.nz</a>
tel: +64 (0)9 923 4611</pre>
</div>
</blockquote></div><br clear="all"><div><br></div><span class="gmail_signature_prefix">-- </span><br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div>What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br>-- Norbert Wiener</div><div><br></div><div><a href="https://urldefense.us/v3/__http://www.cse.buffalo.edu/*knepley/__;fg!!G_uCfscf7eWS!eWw8ZyC03JCY81KS4nuvF6OwPoyRvldIwdZsw_6BlM1OLpJ4cucgOSJ6wetJu-YCCDUSYq0ZI_4rgriZqJYl$" target="_blank">https://www.cse.buffalo.edu/~knepley/</a><br></div></div></div></div></div></div></div></div>