Thanks, Doug.<div><br></div><div>That's exactly correct, in one case I'm missing a sample which should have been at 23:59.999998. I was trying to avoid crossing day boundaries because I understood that was more intensive processing on the DMC end. My process for stitching together traces can handle overlap, so the brute force method would be to just request to 00:00:01 the next day. I'd like to know if there is a more efficient way.</div>
<div><br clear="all"> -- John<br>
<br><br><div class="gmail_quote">On Thu, Jan 26, 2012 at 5:19 PM, Doug Neuhauser <span dir="ltr"><<a href="mailto:doug@seismo.berkeley.edu">doug@seismo.berkeley.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
One suggestion (which unfortunately changes the IRIS web service<br>
time specification) is for time intervals to be half-open invervals,<br>
represented in math notation as<br>
[time1, time2)<br>
This means the time interval where time t >= time1 and t < time2.<br>
<br>
I believe that all IRIS services currently defined a closed interval<br>
[time1, time2] which means the time interval where<br>
time t >= time1 and <= time2.<br>
<br>
Closed intervals make it very hard to request a series of<br>
requests whose results can be concatenated to generate a<br>
contiguous timeseries with no overlap. For day requests,<br>
2 request for:<br>
2007-03-03T00:00:00.0000 to 2007-03-04T00:00:00.0000<br>
2007-03-04T00:00:00.0000 to 2007-03-05T00:00:00.0000<br>
will contains 2 copies of a sample whose timestamp is 2007-03-04T00:00:00.0000<br>
However, if the requests are open intervals, you will never miss a sample or<br>
get a duplicate sample at a request boundary.<br>
<br>
If you are missing 1 sample at a day boundary, it could be that you are missing a<br>
sample timestamped between 59.999 and 00.000 seconds. If you are missing<br>
more than one sample, there is either a timetear (or gap) in the timeseries,<br>
or there is a problem with the IRIS web service.<br>
<br>
- Doug N<div><div class="h5"><br>
<br>
On 1/25/12 10:24 PM, John D. West wrote:<br>
</div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5">
Hi.<br>
<br>
I'm retrieving continuous data using bulkdataselect, one day at a time. A typical request line might look like "TA X16A -- BHZ 2007-03-30T00:00:00 2007-03-30T23:59:59.999"<br>
<br>
Using this method, I occasionally miss one or two samples at the day boundaries. I'm under the impression that the DMC internals make it more efficient to request on day boundaries. How do you recommend I do this to keep the data continuous and not miss samples at the day boundaries?<br>
<br>
Thanks!<br>
<br>
-- John<br>
<br>
<br></div></div>
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<br>
<br>
-- <br>
Doug Neuhauser University of California, Berkeley<br>
<a href="mailto:doug@seismo.berkeley.edu" target="_blank">doug@seismo.berkeley.edu</a> Berkeley Seismological Laboratory<br>
Office: 510-642-0931 215 McCone Hall # 4760<br>
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