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On 02/04/2012 09:48 AM, Johannes Radinger wrote:
<blockquote cite="mid:A8B78F65-A35C-4A92-B9E2-532D9BA0B409@gmx.at"
type="cite">Hi,<br>
<div>
<div>Am 03.02.2012 um 17:30 schrieb Micha Silver:</div>
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<div bidimailui-detected-decoding-type="UTF-8"
text="#000000" bgcolor="#ffffff" style="direction: ltr;"><tt>On
02/03/2012 01:57 PM, Johannes Radinger wrote:</tt>
<blockquote cite="mid:20120203115723.291550@gmx.net"
type="cite">
<pre wrap=""><tt>Hello,
While working on a vectorfile (lines) with 46000 entries in sqlite in GRASS
some questions popped up:
1) Somehow my cat column is double precision instead of integer...Can it be transformed into an integer within GRASS GIS to do some v.select operations with it? If yes, how exactly?
</tt></pre>
</blockquote>
<tt><br>
Converting the values to integer can be done with the
sqlite CAST(cat AS integer). But that probably won't
help. THe column itself needs to be integer type, so I
think you need to make a new cat column and populate it
with integer values:<br>
Using sqlite:<br>
sqlite> alter table <your vector> add column
cat2 integer;<br>
sqlite> update <your vector> set cat2=CAST(cat
AS integer);<br>
</tt></div>
</span></blockquote>
<div><br>
</div>
Thank you for that, but what should I use to call sqlite
commands? Can that be done inside GRASS, is there any tool? Or
should that be </div>
<div>done from any sqlite-management software or from any command
line programm (GRASS console? Mac Terminal?)</div>
<div><br>
</div>
</blockquote>
<br>
Just run: sqlite3 <your grass sqlite db> from the command
line, or any of the sqlite management programs. The Mozilla firefox
sqlite manager is a nice one...<br>
<blockquote cite="mid:A8B78F65-A35C-4A92-B9E2-532D9BA0B409@gmx.at"
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<blockquote cite="mid:20120203115723.291550@gmx.net"
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<pre wrap=""><tt>
2) Is it possible to change the order of the columns in the attribute table?
</tt></pre>
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<tt><br>
In sqlite you can't change the order of the columns, so
you'll need to create a new table ordered the way you
want, then juggle the table names so that the grass
vector "sees" the new reordered table.<br>
Suppose, after the first question above you have a
vector with columns: <br>
cat double, label text, value double, cat2 integer<br>
and you want the reordered table to be: <br>
label, value, cat (the new integer one)<br>
</tt></div>
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<div><br>
</div>
<div>Of course it is not necessary to change the order for
database calls etc. It would just be interesting when I look
into the attribute</div>
<div>table of a vector within GRASS I have to scroll to the very
far rigtht side to get to e.g. my vector name label which is
not that comfortable</div>
<div>for a quick view... Therefore a quick sort (drag and drop)
within the GRASS GUI would be of nice but not necessary of
course...</div>
<div><br>
</div>
<br>
</div>
</blockquote>
<br>
Yes, Moritz explained this quite well with th3 columns="..." option
to v.db.select.<br>
<br>
<blockquote cite="mid:A8B78F65-A35C-4A92-B9E2-532D9BA0B409@gmx.at"
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then:<br>
<br>
sqlite> CREATE TABLE tmp (label text, value double,
cat integer);<br>
sqlite> INSERT INTO tmp (label, value, cat) SELECT
label, value, cat2 FROM <your_vector>;<br>
sqlite> ALTER TABLE <your_vector> RENAME TO
vector_bak;<br>
sqlite> ALTER TABLE tmp RENAME TO
<your_vector>;<br>
<br>
HTH,<br>
Micha<br>
<br>
</tt>
<blockquote cite="mid:20120203115723.291550@gmx.net"
type="cite">
<pre wrap=""><tt>
I am working on GRASS GIS 6.5SVN on Mac OSX.
Best regards,
Johannes
</tt></pre>
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</tt></div>
<tt><br>
</tt>
<pre class="moz-signature" cols="72"><tt>--
Micha Silver
GIS Consultant, Arava Development Co.
<a moz-do-not-send="true" class="moz-txt-link-freetext" href="http://www.surfaces.co.il/">http://www.surfaces.co.il</a></tt></pre>
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<p><br>
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<br>
<pre class="moz-signature" cols="72">--
Micha Silver
GIS Consultant, Arava Development Co.
<a class="moz-txt-link-freetext" href="http://www.surfaces.co.il">http://www.surfaces.co.il</a></pre>
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