<div dir="ltr">I've issued a pull request that fixes this issue:<div><br></div><div><a href="https://bitbucket.org/yt_analysis/yt/pull-requests/2051/create-the-index-before-calling-derived/diff">https://bitbucket.org/yt_analysis/yt/pull-requests/2051/create-the-index-before-calling-derived/diff</a><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Mar 18, 2016 at 2:58 PM, Daniel Fenn <span dir="ltr"><<a href="mailto:dsfenn@gmail.com" target="_blank">dsfenn@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Ah, that worked!<div><br></div><div>Thanks!</div><div><br></div><div>Dan</div></div><div class="HOEnZb"><div class="h5"><div class="gmail_extra"><br><div class="gmail_quote">2016-03-18 15:55 GMT-04:00 Matthew Turk <span dir="ltr"><<a href="mailto:matthewturk@gmail.com" target="_blank">matthewturk@gmail.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi Dan,<br>
<br>
Can you try doing:<br>
<br>
ds.index<br>
<br>
right after ds=yt.load ?  If that fixes it, then I think the solution<br>
will be to make sure the fields have been instantiated before any<br>
quantities get called.<br>
<div><div><br>
On Fri, Mar 18, 2016 at 2:52 PM, Daniel Fenn <<a href="mailto:dsfenn@gmail.com" target="_blank">dsfenn@gmail.com</a>> wrote:<br>
> Hi,<br>
><br>
> I'm trying to calculate the center of mass of my FLASH dataset using the<br>
> following:<br>
><br>
> import yt<br>
> ds = yt.load("path/to/file")<br>
> ad = ds.all_data()<br>
> print ad.quantities.center_of_mass()<br>
><br>
> However, the last line throws the error: 'FLASHDataset' object has no<br>
> attribute 'field_info' .<br>
><br>
> As a test, I ran<br>
><br>
> ds.field_info["flash", "temp"]<br>
><br>
> which gives the same error.<br>
><br>
> Can anyone give me any advice on what's going on and how to get past this<br>
> error?<br>
><br>
> Thanks,<br>
><br>
> Dan<br>
><br>
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