<div dir="ltr"><div>Ok, this is somehow what I did. With QChainage plugin, no need to create new fields and csv table. It directly creates the point geometry layer corresponding to xat(0)/yat(0) and xat(-1)/yat(-1) with $id field, when well setting.<br></div>I also assume that what I was trying to do directly within the line layer field calculator is not (yet) possible.<br><div><br>Thanks.<br><br><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">2015-01-15 15:54 GMT+01:00 Enrico Ferreguti <span dir="ltr"><<a href="mailto:enricofer@gmail.com" target="_blank">enricofer@gmail.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_extra">Ok. so i would proceed degrading line geometry to point geometry creating two X and Y fields in the original table with xat(0) and yat(0) functions. I would add a featureid field with $id function for a following join. Then I would export everything in cvs and import back with "Add Delimited Text Layer" creatin geometry from X and Y fields.<br></div><div class="gmail_extra">From the the degraded new table is now possible to apply geomnearest function joining the added fields with featureid field. <br></div><div class="gmail_extra">...a bit tricky but it should work.<br><br></div><div class="gmail_extra">Regards<br></div><div><div class="h5"><div class="gmail_extra"><br><br></div><div class="gmail_extra"><br><br><div class="gmail_quote">2015-01-15 14:25 GMT+01:00 Junior Delaz <span dir="ltr"><<a href="mailto:delazj@gmail.com" target="_blank">delazj@gmail.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div><div><div><div>Thanks Enrico for your reply and for the plugin.<br><br>I was aware of RefFunctions and has already used it for relational questions. And I agree with Jean that such functions (and others of your plugins) might be core functions. I've moreover reported a feature request to improve usability of all this <a href="https://hub.qgis.org/issues/11680" target="_blank">#11680</a>.<br></div>And I tried it again this time. but the main problem is I don't want to retrieve field value of the nearest point to my line geometry. I want to retrieve field value of the nearest point <b>to the first vertex</b> of my line geometry. While using just geomnearest, i'll get only the nearest point to the whole line. It may be the point at the beginning or the one at the end of the line, I can't know. <br></div>What I did is to create a point file containing my vertices and then use refFunctions to get the nearest station ID. <br><br>But, isn't it possible to do the request without the step of creating new point file? Using in the condition "being nearest to the geomfromWKT('POINT (xat(0) yat(0)) ') of line feature"?<br></div><div>How can I write in the field calculator of a line layer such function : dbquery ('mypointlayer', 'pointID', 'the condition is to be the nearest point to the first vertex of the line')? Or dbvalue? Is it possible to combine reference functions with others?<br><br>And more generally, are Reference functions conditions intended to be only internal to the target layer or can I use values/fields from the source layer? If latter, how can I refer to the source layer in the expression?<br></div><div><br></div><div>Thanks<br></div><br></div></div><div><div><div class="gmail_extra"><br><div class="gmail_quote">2015-01-15 12:05 GMT+01:00 Tijan49 <span dir="ltr"><<a href="mailto:tijan49@yahoo.fr" target="_blank">tijan49@yahoo.fr</a>></span>:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<div>Hi, <br>
I knew about those functions a few weeks ago, and I was really
happy about that, because it is a lack in the basic function.<br>
For I, those new functions should really be in the core project in
the next release ...<br>
Thanks to all the programmers.<br>
Jean<br>
<br>
Le 15/01/2015 11:59, Enrico Ferreguti a écrit :<br>
</div>
<blockquote type="cite"><div><div>
<div dir="ltr">
<div>
<div>
<div>You can use refFunctions (<a href="http://plugins.qgis.org/plugins/refFunctions/" target="_blank">http://plugins.qgis.org/plugins/refFunctions/</a>)
plugin that extends Field Calculator with a new Reference
group.<br>
</div>
Within this group you will find a geomnearest and a
geomdistance function that can help you.<br>
</div>
<br>
</div>
<div>copy and paste from helper screen:<br>
<br>
<span>geomnearest
function</span>
<p style="margin:0px;text-indent:0px"><span style="font-family:"arial,sans-serif";color:rgb(0,0,0)"><br>
Retrieve target field value from the nearest target
feature in target layer </span></p>
<p style="margin:12px 0px;text-indent:0px;background-color:rgb(246,246,246)"><span>Syntax</span><span style="font-family:"arial,sans-serif";color:rgb(0,0,0)"> </span></p>
<p style="margin:12px 0px;text-indent:0px"><span style="font-family:"arial,sans-serif";color:rgb(0,0,0)">geomnearest(</span><span style="font-family:"arial,sans-serif";font-style:italic;color:rgb(0,0,0)">targetLayer,targetField</span><span style="font-family:"arial,sans-serif";color:rgb(0,0,0)">) </span></p>
<p style="margin:12px 0px;text-indent:0px;background-color:rgb(246,246,246)"><span>Arguments</span><span style="font-family:"arial,sans-serif";color:rgb(0,0,0)"> </span></p>
<p style="margin:12px 0px;text-indent:0px"><span style="font-family:"arial,sans-serif";font-style:italic;color:rgb(0,0,0)">targetLayer</span><span style="font-family:"arial,sans-serif";color:rgb(0,0,0)"> → the
name of a currently loaded layer, for example 'myLayer'.<br>
</span><span style="font-family:"arial,sans-serif";font-style:italic;color:rgb(0,0,0)">targetField</span><span style="font-family:"arial,sans-serif";color:rgb(0,0,0)"> → a
field in target layer we want as result when source
feature is within target feature, for example 'myField'. <br>
If targetField is equal to '$geometry' The WKT geometry of
targetFeature willbe retrieved. If otherwise is equal to
'$distance' the calculated distance between source and
target features will be returned<br>
</span><span style="font-family:"arial,sans-serif";font-style:italic;color:rgb(0,0,0)">Number
of feature tested is limited to 100000 to avoid time
wasting loops</span><span style="font-family:"arial,sans-serif";color:rgb(0,0,0)">
</span></p>
<p style="margin:12px 0px;text-indent:0px;background-color:rgb(246,246,246)"><span>Example</span><span style="font-family:"arial,sans-serif";color:rgb(0,0,0)"> </span></p>
<p style="margin:12px 0px;text-indent:0px"><span style="font-family:"arial,sans-serif";color:rgb(0,0,0)">geomnearest('targetLayer','TargetField')
<br>
geomnearest('targetLayer','$geometry') <br>
geomnearest('targetLayer','$distance') </span></p>
<br>
</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">2015-01-15 11:19 GMT+01:00 Junior Delaz
<span dir="ltr"><<a href="mailto:delazj@gmail.com" target="_blank">delazj@gmail.com</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="ltr">
<div>
<div>
<div>
<div>
<div>Hi all,<br>
<br>
</div>
I have two shapefiles : a line one (called
"section") and a point one (called "station")
shapefiles.<br>
</div>
The line shapefiles has fields like ID_section,
ID_first, ID_last<br>
</div>
The point file has an ID_station.<br>
</div>
<div>All these define a kind of network where a section
begins on a station and ends up at another station.<br>
</div>
<div>What I need to do is to fill :<br>
- section ID_first field with the ID_station of the
station that is the closest to the beginning of the
section<br>
- and section ID_last field with the ID_station of the
closest station to the end of the line.<br>
</div>
<div><br>
I can obtain this result while combining many analysis
tools and plugins (QChainage, Spatial_Join...). I know
how I can do it. There might be a way with processing
tools and if somebody has an idea, I'll be glad to
know it however.<br>
<br>
</div>
<div>But what I'm really wondering is if it isn't
directly possible to fill these fields in the Field
calculator using all the nice functions we have.
Indeed, QGIS 2.6 and RefFunctions plugin give
relational fonctions to retrieve values on a specific
layer according to its fields, features values or
localisation.<br>
</div>
<div>I tried many combinations with db_query,
geomnearest, geomRedef, xat/yat, buffer, geometry,
within , attribute (not all at the same time :) )....
I'm pretty sure it's possible but I can't find. And I
don't want to lose all my hair...<br>
</div>
<div><br>
</div>
<div>Does anybody know how I can retrieve in a line
shapefile's field the value of the point feature that
is the closest to the first vertex of this line,
within the field calculator?<br>
</div>
<br>
</div>
Thanks ...<br>
</div>
</blockquote>
</div>
<br>
</div>
<br>
<fieldset></fieldset>
<br>
</div></div><pre>_______________________________________________
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</div>
</blockquote></div><br></div>
</div></div></blockquote></div><br></div></div></div></div>
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