<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Sun, Mar 15, 2015 at 4:08 PM, Rich Shepard <span dir="ltr"><<a href="mailto:rshepard@appl-ecosys.com" target="_blank">rshepard@appl-ecosys.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">On Sun, 15 Mar 2015, Andy Wickert wrote:<br>
<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
EXAMPLE 1:<span><br>
<br>
I want to present a time series of stream gage data. I would like a data<br>
table to have:<br>
<br>
time water_discharge_m3_s sediment_discharge_m3_s<br>
<br>
And to have an entire time series of values for a given grass vector<br>
category (i.e. vector point, in this case).<br>
</span></blockquote>
<br>
Andy,<br>
<br>
This is a typical database table. Each row needs a unique ID. What I do<br>
for all my environmental databases would be something like this:<br>
<br>
CREATE TABLE Discharges (<br>
site VARCHAR(30),<br>
sampdate DATE, -- or use TIMESTAMP to have date and time in a single<br>
samptime TIME, -- field.<br>
h20disch REAL,<br>
seddisc REAL,<br>
PRIMARY KEY (site, sampdate, samptime)<br>
)<br>
<br>
Then assign your points to the site column.<span><br>
<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
EXAMPLE 2:<br>
<br>
I have a series of data on sediment composition at a river site. For each<br>
point, I want to have a 2D data table with multiple values for:<br>
<br>
grain_size lithology<br>
</blockquote>
<br></span>
This would have a similar table structure. Columns (attributes) would<br>
include sediment sample ID (the table's primary key that refers to a table<br>
of sediment samples by location, date, and time), grain size, and<br>
lithography.<br>
<br>
From a statistical analytic point of view I would look at each sample as a<br>
composition and apply models suitable for compositional data analysie (CoDA)<br>
to them. CoDA was developed by geochemists and is appropriate for your data.<br>
<br>
HTH,<br>
<br>
Rich<span><font color="#888888"><br></font></span></blockquote><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><span><font color="#888888">
-- <br>
Richard B. Shepard, Ph.D.<br>
Applied Ecosystem Services, Inc. | Troutdale, OR 97060 USA<br>
<a href="http://www.appl-ecosys.com" target="_blank">www.appl-ecosys.com</a> Voice: <a href="tel:503-667-4517" value="+15036674517" target="_blank">503-667-4517</a> Fax: <a href="tel:503-667-8863" value="+15036678863" target="_blank">503-667-8863</a><br>
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</font></span></blockquote></div><br><div><div><br>Thanks Rich,<br><br></div>So to boil it down to the simplest
part of what you said, the key is just to have an ID column in the GRASS
table that links to a table in a database structure outside of GRASS?
Just to make sure that I was clear: the problem is how to include
multiple rows of data that all correspond to just one point in GIS (so
"grain size" with frequencies in each grain size class or "discharge"
with discharges at different times).<br></div><div><br></div><div>Best,<br></div><div><br></div>Andy <br><span><font color="#888888">
</font></span><br></div></div>