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Thanks to both Leyan and Nathan for their contribution, but it would
be really nice if someone could shed light on the workings and
efficacy of using<br>
<pre wrap=""><b>Vector->Analysis Tools->Sum Line Lengths</b></pre>
Thanks,<br>
Zoltan<br>
<br>
<br>
On 2012/06/20 12:37, Nathan Woodrow wrote:
<blockquote
cite="mid:CAAi8Yg-0rYtE1r2gz4YKF1_xj+NyYJen+_ckSoTDOG8wqTL8Zw@mail.gmail.com"
type="cite">
<pre wrap="">You can use the method that I outline here:
<a class="moz-txt-link-freetext" href="http://woostuff.wordpress.com/2011/02/23/total-length-of-selected-objects-qgis-via-python/">http://woostuff.wordpress.com/2011/02/23/total-length-of-selected-objects-qgis-via-python/</a>
- Nathan
On Wed, Jun 20, 2012 at 8:14 PM, Zoltan Szecsei <a class="moz-txt-link-rfc2396E" href="mailto:zoltans@geograph.co.za"><zoltans@geograph.co.za></a> wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Hi,
I've opened a DGN file of contours, and would like to calculate the sum of
the lengths of all the contours.
<b>Using Vector->Analysis Tools->Sum Line Lengths</b> is totally counter intuitive
(OK, for me!).
Why do I have to have a polygon in order to sum line lengths - In SHAPE file
methodology those geometries are even in separate files!
And then to create a new poly layer in order to see the calculated value
seems kind of arb.
Is the polygon perimeter also added to the calculated length?
If said polygon is purely for creating a selection subset of the
line-lengths to be summed, then why not use the selection tool instead?
When querying an individual line, its length is shown as a derived field. If
there was a way to put derived fields into the attribute tables, then at
least that column could be summed.
Anyway, it seems like I have missed the point of summing line lengths in
this way, so please can someone enlighten me why this methodology is useful.
Thanks & regards,
Zoltan
</pre>
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</blockquote>
<br>
<pre class="moz-signature" cols="72">--
===========================================
Zoltan Szecsei PrGISc [PGP0031]
Geograph (Pty) Ltd.
P.O. Box 7, Muizenberg 7950, South Africa.
65 Main Road, Muizenberg 7945
Western Cape, South Africa.
34° 6'16.35"S 18°28'5.62"E
Tel: +27-21-7884897 Mobile: +27-83-6004028
Fax: +27-86-6115323 <a class="moz-txt-link-abbreviated" href="http://www.geograph.co.za">www.geograph.co.za</a>
===========================================</pre>
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