i not doing anything advanced, at least it shouldnt be. i
have a county wide, line roads dataset and county wide building points
dataset. all i want to do is clip both vectors back to the same
extent. basically i just want the features either clipped to the
boundary of a polygon i built, or even just select overlapping ones,
and write them to a new file.<br>
<br>
i may be missing the concept of this, "features need a category number
in order to be extracted. does d.what.vect show cat numbers for your
points?"<br>
<br>
d.what.vect shows catagory numbers for the building points. I'm
not sure i understand what the category has to do with v.select.<br>
<br>
<a href="http://v.info">v.info</a> clipper does show boundaries and centroids and area (and
islands?!?) i recently modified the clipper polygon box,
and it seems that the centroid is outside the box now. i'll put
it in and give it another whirl.<br>
<br>
thanks for the help! <br><br><div><span class="gmail_quote">On 6/22/06, <b class="gmail_sendername">Hamish</b> <<a href="mailto:hamish_nospam@yahoo.com">hamish_nospam@yahoo.com</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
> i'm using v.select as such:<br>><br>> v.select ainput=buildings atype=point alayer=1 binput=clipper<br>> btype=area blayer=1 outpout=buildclip operator=overlap<br>><br>> where buildings are a point, with layer 1 (verified through QGIS)
<br>> where clipper is a polygon that is the bounds i want to pull the<br>> building points from. the odd thing about this dataset, is that when<br>> i go to load in QGIS, there are two layer options, layer 0 which is
<br>> polygon and layer 1 which is line.<br>><br>> i cant specify blayer=0 in this function or it says must be 1 or<br>> greater.<br>><br>> is there a way to put the polygon layer on layer 1? i can only think
<br>> this might be why there's a problem. I still dont really grasp the<br>> layers concept very well. i understand it has to do with linking<br>> features to a database, but why does it put different features on
<br>> different layers?<br>><br>> the output i get is a file with no data in it.<br><br><br>I don't think QGIS layers == GRASS layers.<br><br>Unless you are doing something advanced, usually grass vector layer is 1
<br>and you can forget about that.<br><br>"<a href="http://v.info">v.info</a> clipper" show boundaries + centroids or lines?<br><br>features need a category number in order to be extracted. does<br>d.what.vect show cat numbers for your points?
<br><br>v.select works well and should be pretty simple, so don't give up.<br><br><br>Hamish<br></blockquote></div><br>