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<p>I tried a lot ...</p>
<p>I have a point-layer, I put this code in symbol -> single
symbol -> geometrygenerator<br>
</p>
<p>What is wrong?<br>
</p>
<p><br>
</p>
<p>geom_to_wkt<br>
(<br>
make_line<br>
(<br>
make_point<br>
(<br>
5826542.703128459,<br>
797907.3304607988<br>
),<br>
make_point<br>
(<br>
5827473.536854242,<br>
796987.0074038045<br>
),<br>
make_point<br>
(<br>
5827167.893279332,<br>
795128.2317764781<br>
),<br>
make_point<br>
(<br>
5826835.7783904355,<br>
793227.8583700341<br>
)<br>
)<br>
)<br>
<br>
</p>
<div class="moz-cite-prefix">Am 13.11.2020 um 15:24 schrieb Andreas
Neumann:<br>
</div>
<blockquote type="cite"
cite="mid:8aacb7b7-3d1d-cedd-7b71-fe0781da9496@carto.net">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<p>Hi Nicolas,<br>
</p>
<p>Yes - but that doesn't magically turn a "non geometry" table
into a "geometry table" - as far as I know. So you probably need
to create a "Virtual Layer" and create the geometry similar to
what you propose.<br>
</p>
<p>Andreas<br>
</p>
<div class="moz-cite-prefix">Am 13.11.20 um 15:22 schrieb Nicolas
Cadieux:<br>
</div>
<blockquote type="cite"
cite="mid:E3F9A1DC-1A61-4A25-82DC-BA85EE92CCF8@gmail.com">
<meta http-equiv="content-type" content="text/html;
charset=UTF-8">
Hi,
<div>You can create a geometry from WKT if you have x and y
fields using and expression in the field calculator.</div>
<div>
<pre style="color: var(--highlight-color); -webkit-text-size-adjust: auto; margin-top: 0px; margin-bottom: 0px; padding: 12px; border: 0px; font-family: Consolas, Menlo, Monaco, "Lucida Console", "Liberation Mono", "DejaVu Sans Mono", "Bitstream Vera Sans Mono", "Courier New", monospace, sans-serif; font-stretch: inherit; line-height: 1.30769231; font-size: 13px; vertical-align: baseline; box-sizing: inherit; width: auto; max-height: 600px; overflow: auto; border-top-left-radius: 5px; border-top-right-radius: 5px; border-bottom-right-radius: 5px; border-bottom-left-radius: 5px; word-wrap: normal;"><code style="margin: 0px; padding: 0px; border: 0px; font-family: Consolas, Menlo, Monaco, "Lucida Console", "Liberation Mono", "DejaVu Sans Mono", "Bitstream Vera Sans Mono", "Courier New", monospace, sans-serif; font-style: inherit; font-variant-caps: inherit; font-stretch: inherit; line-height: inherit; vertical-align: baseline; box-sizing: inherit; white-space: inherit; color: var(--black-800); border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px;">geom_from_wkt('POINT('||"x"||' '||"y"||')')</code></pre>
<div><br>
</div>
<div><a
href="https://en.wikipedia.org/wiki/Well-known_text_representation_of_geometry"
moz-do-not-send="true">https://en.wikipedia.org/wiki/Well-known_text_representation_of_geometry</a></div>
<div><br>
</div>
<div dir="ltr">Nicolas Cadieux</div>
<div dir="ltr"><br>
<blockquote type="cite">Le 13 nov. 2020 à 09:07, Andreas
Neumann <a class="moz-txt-link-rfc2396E"
href="mailto:a.neumann@carto.net" moz-do-not-send="true"><a.neumann@carto.net></a>
a écrit :<br>
<br>
</blockquote>
</div>
<blockquote type="cite">
<div dir="ltr">
<meta http-equiv="Content-Type" content="text/html;
charset=UTF-8">
<p>Hi</p>
<p>Neither GeometryGenerators nor Vector Field Markers
work on tables without geometry, unfortunately. You
didn't inform us, that you don't have geometry in your
table.<br>
</p>
<p>You can, however, create a "Virtual Layer" and write
some SQL to create a geometry from your attributes: menu
"Layer" --> "Create Layer" --> "New Virtual Layer"
- where you can use your existing tables and create a
new geometry column with SQL. See <a
class="moz-txt-link-freetext"
href="https://docs.qgis.org/testing/en/docs/user_manual/managing_data_source/create_layers.html#creating-virtual-layers"
moz-do-not-send="true">https://docs.qgis.org/testing/en/docs/user_manual/managing_data_source/create_layers.html#creating-virtual-layers</a></p>
<p>Or, if your table is a CSV file, then you can assign
attribute columns to a point geometry and then just hide
the point rendering if you don't need it.<br>
</p>
<p>This is an unfortunate limitation of QGIS, that there
is no "easy" way to add a geometry column to table that
doesn't have geometry (or if it is possible, then I
don't know it).</p>
<p>Hope this helps you,</p>
<p>Andreas<br>
</p>
<div class="moz-cite-prefix">Am 13.11.20 um 14:52 schrieb
L.W.:<br>
</div>
<blockquote type="cite"
cite="mid:7f9befd5-d44c-8aec-7036-71461c7964e2@gmx.de">
<meta http-equiv="Content-Type" content="text/html;
charset=UTF-8">
<p>Does it works on Layers with no geometry?</p>
<p>My layers do not have a geometry.</p>
<p><br>
</p>
<div class="moz-cite-prefix">Am 13.11.2020 um 11:56
schrieb Andreas Neumann:<br>
</div>
<blockquote type="cite"
cite="mid:80d2b9f3-0896-999d-a5ab-17ad4573d522@carto.net">
<meta http-equiv="Content-Type" content="text/html;
charset=UTF-8">
<p>Yes, you need point data to start from, but then
vectors can bei/are generated from the attributes
you mentioned.</p>
<p>Andreas<br>
</p>
<div class="moz-cite-prefix">Am 13.11.20 um 11:47
schrieb L.W.:<br>
</div>
<blockquote type="cite"
cite="mid:cd1f5b7c-4703-530f-d5b7-b51caa5632d5@gmx.de">
<meta http-equiv="Content-Type" content="text/html;
charset=UTF-8">
<p>from the docs ...</p>
<p>****It can only be used to render point data****</p>
<h4 style="box-sizing: border-box; margin-top: 0px;
font-weight: 700; font-family: "Roboto
Slab", ff-tisa-web-pro, Georgia, Arial,
sans-serif; font-size: 18.4px; color: rgb(64, 64,
64); font-style: normal; font-variant-ligatures:
normal; font-variant-caps: normal; letter-spacing:
normal; orphans: 2; text-align: start;
text-indent: 0px; text-transform: none;
white-space: normal; widows: 2; word-spacing: 0px;
-webkit-text-stroke-width: 0px; background-color:
rgb(252, 252, 252); text-decoration-style:
initial; text-decoration-color: initial;"><a
class="toc-backref"
href="https://docs.qgis.org/3.10/en/docs/user_manual/style_library/symbol_selector.html?#id15"
style="box-sizing: border-box; color: rgb(64,
64, 64); text-decoration: none; cursor: pointer;
outline-width: 0px !important; user-select: auto
!important;" moz-do-not-send="true"><span
class="section-number" style="box-sizing:
border-box;">12.2.2.2.6.<span> </span></span>The
Vector Field Marker</a></h4>
<p class="" style="box-sizing: border-box;
line-height: 24px; font-size: 16px; margin: 0px
0px 24px; color: rgb(64, 64, 64); font-family:
Lato, proxima-nova, "Helvetica Neue",
Arial, sans-serif; font-style: normal;
font-variant-ligatures: normal; font-variant-caps:
normal; font-weight: 400; letter-spacing: normal;
orphans: 2; text-align: start; text-indent: 0px;
text-transform: none; white-space: normal; widows:
2; word-spacing: 0px; -webkit-text-stroke-width:
0px; background-color: rgb(252, 252, 252);
text-decoration-style: initial;
text-decoration-color: initial;">The vector field
marker is used to display vector field data such
as earth deformation, tidal flows, and the like.
It displays the vectors as lines (preferably
arrows) that are scaled and oriented according to
selected attributes of data points. ****It can
only be used to render point data****; line and
polygon layers are not drawn by this symbology.</p>
<p style="box-sizing: border-box; line-height: 24px;
font-size: 16px; margin: 0px 0px 24px; color:
rgb(64, 64, 64); font-family: Lato, proxima-nova,
"Helvetica Neue", Arial, sans-serif;
font-style: normal; font-variant-ligatures:
normal; font-variant-caps: normal; font-weight:
400; letter-spacing: normal; orphans: 2;
text-align: start; text-indent: 0px;
text-transform: none; white-space: normal; widows:
2; word-spacing: 0px; -webkit-text-stroke-width:
0px; background-color: rgb(252, 252, 252);
text-decoration-style: initial;
text-decoration-color: initial;">The vector field
is defined by attributes in the data, which can
represent the field either by:</p>
<ul class="simple" style="box-sizing: border-box;
margin: 0px 0px 24px; padding: 0px; list-style:
disc; line-height: 24px; color: rgb(64, 64, 64);
font-family: Lato, proxima-nova, "Helvetica
Neue", Arial, sans-serif; font-size: 16px;
font-style: normal; font-variant-ligatures:
normal; font-variant-caps: normal; font-weight:
400; letter-spacing: normal; orphans: 2;
text-align: start; text-indent: 0px;
text-transform: none; white-space: normal; widows:
2; word-spacing: 0px; -webkit-text-stroke-width:
0px; background-color: rgb(252, 252, 252);
text-decoration-style: initial;
text-decoration-color: initial;">
<li style="box-sizing: border-box; list-style:
disc; margin-left: 24px;">
<p style="box-sizing: border-box; line-height:
24px; font-size: 16px; margin: 0px;"><strong
style="box-sizing: border-box; font-weight:
700;">cartesian</strong><span> </span>components
(<code class="docutils literal notranslate"
style="box-sizing: border-box; font-family:
SFMono-Regular, Menlo, Monaco, Consolas,
"Liberation Mono", "Courier
New", Courier, monospace; font-size:
12px; white-space: nowrap; max-width: 100%;
background: rgb(255, 255, 255); border: 1px
solid rgb(225, 228, 229); padding: 2px 5px;
color: rgb(231, 76, 60); overflow-x: auto;"><span
class="pre" style="box-sizing:
border-box;">x</span></code><span> </span>and<span> </span><code
class="docutils literal notranslate"
style="box-sizing: border-box; font-family:
SFMono-Regular, Menlo, Monaco, Consolas,
"Liberation Mono", "Courier
New", Courier, monospace; font-size:
12px; white-space: nowrap; max-width: 100%;
background: rgb(255, 255, 255); border: 1px
solid rgb(225, 228, 229); padding: 2px 5px;
color: rgb(231, 76, 60); overflow-x: auto;"><span
class="pre" style="box-sizing:
border-box;">y</span></code><span> </span>components
of the field)</p>
</li>
<li style="box-sizing: border-box; list-style:
disc; margin-left: 24px;">
<p style="box-sizing: border-box; line-height:
24px; font-size: 16px; margin: 0px;">or<span> </span><strong
style="box-sizing: border-box; font-weight:
700;">polar</strong><span> </span>coordinates:
in this case, attributes define<span> </span><code
class="docutils literal notranslate"
style="box-sizing: border-box; font-family:
SFMono-Regular, Menlo, Monaco, Consolas,
"Liberation Mono", "Courier
New", Courier, monospace; font-size:
12px; white-space: nowrap; max-width: 100%;
background: rgb(255, 255, 255); border: 1px
solid rgb(225, 228, 229); padding: 2px 5px;
color: rgb(231, 76, 60); overflow-x: auto;"><span
class="pre" style="box-sizing:
border-box;">Length</span></code><span> </span>and<span> </span><code
class="docutils literal notranslate"
style="box-sizing: border-box; font-family:
SFMono-Regular, Menlo, Monaco, Consolas,
"Liberation Mono", "Courier
New", Courier, monospace; font-size:
12px; white-space: nowrap; max-width: 100%;
background: rgb(255, 255, 255); border: 1px
solid rgb(225, 228, 229); padding: 2px 5px;
color: rgb(231, 76, 60); overflow-x: auto;"><span
class="pre" style="box-sizing:
border-box;">Angle</span></code>. The
angle may be measured either clockwise from
north, or Counterclockwise from east, and may
be either in degrees or radians.</p>
</li>
<li style="box-sizing: border-box; list-style:
disc; margin-left: 24px;">
<p style="box-sizing: border-box; line-height:
24px; font-size: 16px; margin: 0px;">or as<span> </span><strong
style="box-sizing: border-box; font-weight:
700;">height only</strong><span> </span>data,
which displays a vertical arrow scaled using
an attribute of the data. This is appropriate
for displaying the vertical component of
deformation, for example.</p>
</li>
</ul>
<p style="box-sizing: border-box; line-height: 24px;
font-size: 16px; margin: 0px 0px 24px; color:
rgb(64, 64, 64); font-family: Lato, proxima-nova,
"Helvetica Neue", Arial, sans-serif;
font-style: normal; font-variant-ligatures:
normal; font-variant-caps: normal; font-weight:
400; letter-spacing: normal; orphans: 2;
text-align: start; text-indent: 0px;
text-transform: none; white-space: normal; widows:
2; word-spacing: 0px; -webkit-text-stroke-width:
0px; background-color: rgb(252, 252, 252);
text-decoration-style: initial;
text-decoration-color: initial;">The magnitude of
field</p>
<p style="box-sizing: border-box; line-height: 24px;
font-size: 16px; margin: 0px 0px 24px; color:
rgb(64, 64, 64); font-family: Lato, proxima-nova,
"Helvetica Neue", Arial, sans-serif;
font-style: normal; font-variant-ligatures:
normal; font-variant-caps: normal; font-weight:
400; letter-spacing: normal; orphans: 2;
text-align: start; text-indent: 0px;
text-transform: none; white-space: normal; widows:
2; word-spacing: 0px; -webkit-text-stroke-width:
0px; background-color: rgb(252, 252, 252);
text-decoration-style: initial;
text-decoration-color: initial;"><br>
</p>
<div class="moz-cite-prefix">Am 13.11.2020 um 11:34
schrieb Andreas Neumann:<br>
</div>
<blockquote type="cite"
cite="mid:9d5955ce-6f3b-14ba-b27c-5f409d3382cd@carto.net">Or
even easier: use the "Vector Field Marker": <br>
<br>
<a class="moz-txt-link-freetext"
href="https://docs.qgis.org/3.10/en/docs/user_manual/style_library/symbol_selector.html?#the-vector-field-marker"
moz-do-not-send="true">https://docs.qgis.org/3.10/en/docs/user_manual/style_library/symbol_selector.html?#the-vector-field-marker</a>
<br>
<br>
Am 13.11.20 um 11:33 schrieb Andreas Neumann: <br>
<blockquote type="cite">Hi, <br>
<br>
Yes - you can use Geometry Generators for that.
Use the make_point() and make_line() expressions
for that. <br>
<br>
See <a class="moz-txt-link-freetext"
href="https://docs.qgis.org/3.10/en/docs/user_manual/style_library/symbol_selector.html?highlight=geometry%20generator#the-geometry-generator"
moz-do-not-send="true">https://docs.qgis.org/3.10/en/docs/user_manual/style_library/symbol_selector.html?highlight=geometry%20generator#the-geometry-generator</a><br>
<br>
Greetings, <br>
Andreas <br>
<br>
Am 13.11.20 um 11:26 schrieb L.W.: <br>
<blockquote type="cite">Hi, <br>
<br>
is it possible to draw automatically a line
between two points defined <br>
by 4 fields (x1,y1 - x2,y2) in an
attributetable? <br>
<br>
but I do not want to add a line-layer based on
this table nor want to <br>
draw the line by hand. <br>
<br>
thanks <br>
<br>
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