QGIS » QGIS Application

In the meantime, select the vector layer then open the QGis python console and run:

iface = qgis.utils.iface; vl = iface.activeLayer(); iface.addVectorLayer(vl.source(), vl.name() + "_clone", vl.providerType())

You can also create a little plugin using the previous snippet.

Sorry, I've misunderstood the subject. The previous code adds to the map the same sublayer.

It's difficult to do it using a one-line python script like the previous one, but if you know the sublayer name you can just replace vl.source() with vl.source().split("|")[0] + "|layername=my_sublayer_name" where my_sublayer_name is the name of your sublayer.

I already found several past feature requests which weren't processed or where the relevance of the topic didn't get clear enough.
#1483
#3554
Working with complex datasets nearly always requires building views for different aspects of the underlying data.
Having to add the same dataset through the file wizard all the time is a tedious task when you need multiple of these views (e.g. queries, different labeling, colors etc)

Use case: I have 13 groups of monitoring plots, where i have to produce overview maps of. For this, i need as basis a point, line and area layer which i then query for the group-id and put those layers in a group within the TOC for quick on/off of the features.

Having the possibility to quickly duplicate the original set for performing queries and changing additional setting would be a real helper.
Shouldn't mention it, but in ArcGIS, this is a basic feature for a long time (right-click action on layer in TOC to duplicate it).

Coding python scripts themselves is beyond average users abilities i fear...

Olivier redlead wrote:

Often you want to display one Shapefile with several layers (example : for the shapefile LandUse.shp, show column "land_use_current" on one layer, and "land_use_projet" on another layer)

Am I missing something here? I thought a shapefile could only contain a single layer...
Do you mean you want to display different labels depending on the contents of different columns? This is possible with the new expression based labelling, but they will all be formatted the same. If you want to format them differently, then you need rule-based labelling, and there is already a ticket open for that.
Or do you mean you want to run several queries on the layer, based on different columns, and use different symbols for each one? This is possible with the rule-based renderer.

Bernd Vogelgesang wrote:

put those layers in a group within the TOC for quick on/off of the features.

Ah, OK. That's the use case.
Yes, I've found myself wanting to toggle the visibility of features per rule when using the rule based renderer. As long as that isn't possible then I'm sure plenty of people would appreciate a "duplicate layer" plugin.

Should this be merged with #1483?
N.B. copy and paste (#1483) would be slightly better than duplicate, as you could paste into a different QGIS project.

The duplicate layer button/option on the right click menu would be a great addition.

A slight extension of this would be to enable you to add a layer for each value in a column of a dataset.

For example, say I have a table with land uses (say 10 different types), and I want to create a separate layer with each land use in it. At the moment you would have to add the layer 10 number of times, and then do right click > query 10 times. A simple way to add a layer for each category in the land use type column would save a lot of time in this case.

Alexander Bruy wrote:

Implemented in c11df1aa79

great addition Alexander! Thanks!