Hi,
Any csv with a wkt field will behave just like any shape file. Since we can’t
add a new field to a csv as it’s in read only mode, you have to export it to an
editable format like a virtual layer, dbf, or SpatiaLite and then create the
geometries.
Nicolas Cadieux
> Le 13 nov. 2020 à 09:24, Andreas Neumann <a.neum...@carto.net> a écrit :
>
>
> Hi Nicolas,
>
> 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.
>
> Andreas
>
> Am 13.11.20 um 15:22 schrieb Nicolas Cadieux:
>> Hi,
>> You can create a geometry from WKT if you have x and y fields using and
>> expression in the field calculator.
>> geom_from_wkt('POINT('||"x"||' '||"y"||')')
>>
>> https://en.wikipedia.org/wiki/Well-known_text_representation_of_geometry
>>
>> Nicolas Cadieux
>>
>>> Le 13 nov. 2020 à 09:07, Andreas Neumann <a.neum...@carto.net> a écrit :
>>>
>>>
>>> Hi
>>>
>>> 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.
>>>
>>> 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
>>> https://docs.qgis.org/testing/en/docs/user_manual/managing_data_source/create_layers.html#creating-virtual-layers
>>>
>>> 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.
>>>
>>> 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).
>>>
>>> Hope this helps you,
>>>
>>> Andreas
>>>
>>> Am 13.11.20 um 14:52 schrieb L.W.:
>>>> Does it works on Layers with no geometry?
>>>>
>>>> My layers do not have a geometry.
>>>>
>>>>
>>>>
>>>> Am 13.11.2020 um 11:56 schrieb Andreas Neumann:
>>>>> Yes, you need point data to start from, but then vectors can bei/are
>>>>> generated from the attributes you mentioned.
>>>>>
>>>>> Andreas
>>>>>
>>>>> Am 13.11.20 um 11:47 schrieb L.W.:
>>>>>> from the docs ...
>>>>>>
>>>>>> ****It can only be used to render point data****
>>>>>>
>>>>>> 12.2.2.2.6. The Vector Field Marker
>>>>>>
>>>>>> 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.
>>>>>>
>>>>>> The vector field is defined by attributes in the data, which can
>>>>>> represent the field either by:
>>>>>>
>>>>>> cartesian components (x and y components of the field)
>>>>>> or polar coordinates: in this case, attributes define Length and Angle.
>>>>>> The angle may be measured either clockwise from north, or
>>>>>> Counterclockwise from east, and may be either in degrees or radians.
>>>>>> or as height only 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.
>>>>>> The magnitude of field
>>>>>>
>>>>>>
>>>>>>
>>>>>> Am 13.11.2020 um 11:34 schrieb Andreas Neumann:
>>>>>>> Or even easier: use the "Vector Field Marker":
>>>>>>>
>>>>>>> https://docs.qgis.org/3.10/en/docs/user_manual/style_library/symbol_selector.html?#the-vector-field-marker
>>>>>>>
>>>>>>>
>>>>>>> Am 13.11.20 um 11:33 schrieb Andreas Neumann:
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> Yes - you can use Geometry Generators for that. Use the make_point()
>>>>>>>> and make_line() expressions for that.
>>>>>>>>
>>>>>>>> See
>>>>>>>> https://docs.qgis.org/3.10/en/docs/user_manual/style_library/symbol_selector.html?highlight=geometry%20generator#the-geometry-generator
>>>>>>>>
>>>>>>>> Greetings,
>>>>>>>> Andreas
>>>>>>>>
>>>>>>>> Am 13.11.20 um 11:26 schrieb L.W.:
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> is it possible to draw automatically a line between two points
>>>>>>>>> defined
>>>>>>>>> by 4 fields (x1,y1 - x2,y2) in an attributetable?
>>>>>>>>>
>>>>>>>>> but I do not want to add a line-layer based on this table nor want to
>>>>>>>>> draw the line by hand.
>>>>>>>>>
>>>>>>>>> thanks
>>>>>>>>>
>>>>>>>>> _______________________________________________
>>>>>>>>> Qgis-user mailing list
>>>>>>>>> Qgis-user@lists.osgeo.org
>>>>>>>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>>>>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>>>>> _______________________________________________
>>>>>>>> Qgis-user mailing list
>>>>>>>> Qgis-user@lists.osgeo.org
>>>>>>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>>>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>>>> _______________________________________________
>>>>>>> Qgis-user mailing list
>>>>>>> Qgis-user@lists.osgeo.org
>>>>>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> Qgis-user mailing list
>>>>>> Qgis-user@lists.osgeo.org
>>>>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Qgis-user mailing list
>>>>> Qgis-user@lists.osgeo.org
>>>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>
>>>>
>>>> _______________________________________________
>>>> Qgis-user mailing list
>>>> Qgis-user@lists.osgeo.org
>>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>> _______________________________________________
>>> Qgis-user mailing list
>>> Qgis-user@lists.osgeo.org
>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
_______________________________________________
Qgis-user mailing list
Qgis-user@lists.osgeo.org
List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
