<div class="socmaildefaultfont" dir="ltr" style="font-family:Arial, Helvetica,
sans-serif;font-size:10pt" ><div dir="ltr" >Hello again!</div>
<div dir="ltr" > </div>
<div dir="ltr" >I'm writing to let you know about the availability of
<strong>HDF5-UDF 1.2</strong>. You probably remember it, but it doesn’t hurt to
state that the tool allows <strong>embedding routines written in C/C++, Python
or Lua on HDF5/NetCDF files</strong> in a way that such routines execute each
time the dataset is read.</div>
<div dir="ltr" > </div>
<div dir="ltr" >This new release comes with an exciting new feature: the
ability to <strong>output compounds and string datatypes</strong>. This means
that it's now possible to take a CSV file as input and dynamically generate
HDF5 compound datasets as output. And the best part is that it's quite easy to
do it, as the snippets below show.</div>
<div dir="ltr" > </div>
<div dir="ltr" >The new release is available on the project page at <a
href="https://github.com/lucasvr/hdf5-udf";
>https://github.com/lucasvr/hdf5-udf</a>. Feedback is welcome as usual!</div>
<div dir="ltr" > </div>
<div dir="ltr" >Best regards,</div>
<div dir="ltr" >Lucas</div>
<div dir="ltr" > </div>
<div dir="ltr" > </div>
<div dir="ltr" >
<div><strong>Snippet of albumlist.csv:</strong></div>
<div><pre><code class="hljs javascript" ><span class="hljs-built_in" >
Number</span>,Year,Album,Artist,Genre
<span class="hljs-number" > 1</span>,<span class="hljs-number"
>1967</span>,Sgt. Peppers Lonely Hearts Club Band,The Beatles,Rock
<span class="hljs-number" > 2</span>,<span class="hljs-number"
>1966</span>,Pet Sounds,The Beach Boys,Rock
<span class="hljs-number" > 3</span>,<span class="hljs-number"
>1966</span>,Revolver,The Beatles,Rock
</code></pre>
<div> </div>
<div><strong><code class="hljs javascript" ><span
style="font-family:Arial,Helvetica,sans-serif;" >User-Defined
Function:</span></code></strong></div>
<div><pre><code class="hljs python" ><span class="hljs-function" ><span
class="hljs-keyword" > def</span> <span class="hljs-title"
>dynamic_dataset</span><span class="hljs-params" >()</span>:</span>
udf_data = lib.getData(<span class="hljs-string" >"GreatestAlbums"</span>)
<span class="hljs-keyword" > with</span> open(<span class="hljs-string"
>"albumlist.csv"</span>) <span class="hljs-keyword" >as</span> f:
<span class="hljs-comment" ># Skip the header</span>
f.readline()
<span class="hljs-keyword" > for</span> i, line <span
class="hljs-keyword" >in</span> enumerate(f.readlines()):
<span class="hljs-comment" ># Split the line using "," as
separator</span> elements = [col.strip(<span class="hljs-string"
>"\n"</span>) <span class="hljs-keyword" >for</span> col <span
class="hljs-keyword" >in</span> line.split(<span class="hljs-string"
>","</span>)]
<span class="hljs-comment" ># Generate compound members
on-the-fly</span> udf_data[i].id = int(elements[<span
class="hljs-number" >0</span>])
udf_data[i].year = int(elements[<span class="hljs-number"
>1</span>])
lib.setString(udf_data[i].album, elements[<span
class="hljs-number" >2</span>])
lib.setString(udf_data[i].artist, elements[<span
class="hljs-number" >3</span>])
lib.setString(udf_data[i].genre, elements[<span
class="hljs-number" >4</span>])
</code></pre>
<div> </div>
<div><strong>Command to embed the User-Defined Function on the HDF5/NetCDF
file:</strong></div>
<div><pre><code class="hljs ruby" > $ hdf5-udf file.nc4 dynamic_dataset.py \
<span class="hljs-string"
>'GreatestAlbums:{id:int32,year:int16,album:string(40),artist:string,genre:string}:500'</span></code></pre>
<div> </div>
<div><strong>First few entries of the dynamically generated
dataset:</strong></div>
<div><pre><code class="hljs ruby" > $ h5dump -O -d /GreatestAlbums file.nc4
(<span class="hljs-number" >0</span>): {
<span class="hljs-number" >1</span>,
<span class="hljs-number" >1967</span>,
<span class="hljs-string" >"Sgt. Peppers Lonely Hearts Club
Band"</span>,
<span class="hljs-string" >"The Beatles"</span>,
<span class="hljs-string" >"Rock"</span> },
(<span class="hljs-number" >1</span>): {
<span class="hljs-number" >2</span>,
<span class="hljs-number" >1966</span>,
<span class="hljs-string" >"Pet Sounds"</span>,
<span class="hljs-string" >"The Beach Boys"</span>,
<span class="hljs-string" >"Rock"</span> },
(<span class="hljs-number" >2</span>): {
<span class="hljs-number" >3</span>,
<span class="hljs-number" >1966</span>,
<span class="hljs-string" >"Revolver"</span>,
<span class="hljs-string" >"The Beatles"</span>,
<span class="hljs-string" >"Rock"</span> },
...
</code></pre></div></div></div></div></div></div><BR>
