0
votes
1answer
15 views

QGIS 2.2 - expression string builder to ignore NULL values

Simply put, I would like to create a rule-based filter whereby you add 2 columns together and you get a certain colour as a result. However, some fields in Column_1 may be NULL and those exact same ...
0
votes
0answers
22 views

How to intersect more than 2 layers in QGIS

I have a dozen layers, some intersecting with others. Using the Intersect tool only allows 2 layers at a time but can you add extra layers to find where it intersects? Even if it's 3 layers as shown ...
0
votes
0answers
12 views

Layer offset issue in QGIS 2.0.1

I have two loaded WMS layer and want to change their position relative to each other. First, I tried to use Layer class and write some kind of plugin, but I can't find any method that allow to change ...
1
vote
0answers
10 views

Can QGIS2 refresh layers without the need to reclassify each layer individually?

I have a set of layers which I'd like to have refreshed each time I open QGIS2.2.0 (Windows 7). Each of 14 layers (polygons) is linked via a join to a csv file with no geometry. The layer displays a ...
0
votes
0answers
10 views

In QGIS Process Modeller, is it possible to automatically run a function on several layers without listing all combinations?

Trying to develop a Model which includes finding any intersections between layers and then merging them all into a single layer. I have 12 layers in total, it's not really efficient to list all the ...
0
votes
0answers
11 views

Can a joined-layer have its attribute changed depending on what layers are selected/deselected?

Using QGIS, I have a polygon-grid layer which covers everything, Layer_All joined with 2 other grid layers: Layer_1 and Layer_2, both of which intersect at various points. I would like Layer_All to ...
1
vote
1answer
66 views

QGIS/PostGIS layer styles

I've made a plugin asking for login credentials to a DB. Once logged in, the plugin is loading some layers from the DB. In the DB there are both admin and "normal" users. I've saved two styles to the ...
0
votes
1answer
29 views

Displaying QGIS layer after loading with Python

I'm successfully loading several layers with Python, but can only get to see them in the map window if I manually zoom to extent afterwards. Once the last layer is loaded I call zoom to extent in the ...
0
votes
1answer
55 views

Layer relations via Python

Is it possible to, through Python, to create the relations that it's possible to create in Layers/Properties/Fields/Relations, and if so how? I first thought these were saved in the styles, but that ...
0
votes
1answer
44 views

How to disable “Simplify geometry” via Python?

After I've loaded a layer from a table in my db I'd like to disable the 'Simplify geometry' (found in Layers/Properties/Rendering) programatically using Python. I've tried several versions of ...
1
vote
1answer
53 views

How can I copy columns from layer 1 to layer 2?

I have two layers, the first layer is pipe: that has some fields (column) title like : length, id, material. Also I have another layer that is empty (without any fields). How can I copy fields ...
2
votes
1answer
41 views

How to select only polygons that overlap with another layer?

I have two shapefile layers created from different thresholds from a predictive model (Pink=80; Yellow=95). Is there a way to create a new layer of only those pink polygons that contain yellow ...
0
votes
0answers
51 views

How to activate edit tools

I have opened a project I worked on earlier on another machine, but the edit tools are not active, so i cant turn on editing to change a layer. What is the reason for them to be gray, and how can i ...
0
votes
1answer
80 views

Code works on python console in QGIS but same doesn't work in stand alone script

I'm trying map rendering with stand alone script, so I have small script which works fine in python console provided QGIS, however when I run same code in stand-alone script it executes without error, ...
1
vote
2answers
40 views

Using Qt Designer to Create a Form in QGIS that can search for a specific point in a layer

Good Day! I would like to ask if you can create a form in Qt Designer to create a form that can search for a point on the map using data that the user will provide such as the Name. I am currently ...
0
votes
0answers
20 views

Show the paths but not roadsides and driveways in the line layer

I want to display paths in the woods but the paths are all in One (line) layer that contains all roadsides, pavements, drivvays, but also paths, tractor road and other relevant roads in, and up to the ...
1
vote
1answer
47 views

QGIS Quickly switching overlapping raster images

I'm new to QGIS, and haven't used arcGIS in about 5 years, however I've just seen someone using arcGIS and was able to quickly switch between overlapping rasters when checking registration. The top ...
4
votes
0answers
63 views

How can I modify layer order with the QGIS python API

Typically, after a new_layer = addRasterLayer(...) that inserts new_layer before the active layer, I'd like to move it to the top of the table of contents. How to do it? I use an existing QGIS ...
0
votes
0answers
31 views

Crash when editing a layer and when saving in QGIS

When I edit the layers, and its small changes like adding a name (or make it appear in the map), QGIS very often crashes (like for every third or fourth or fifth edit, seldom gets past ten edits ...
1
vote
2answers
60 views

How to avoid “Handle bad layers” message when using QGIS Flowmapper plugin?

In QGIS, if I close a project and try to open it a few days later I often get a message that says "Handle bad layers". This is very frustrating because when I open the project various layers will have ...
0
votes
2answers
68 views

Show only some buildings

How do I show only some buildings? I only need to show 3 cabins in the forrest, but not every house in the whole village around, and the city close by. Maybe some of the symbol buildings in the city ...
3
votes
2answers
153 views

Show alternating contour lines

Is it possible to show only every other counture line? And how do you do that? (Im new to QGIS Lisboa 1.8.0, but even newer to QGIS Dufour 2.0.1, but have used ArcGIS a bit a while ago, and also ...
0
votes
1answer
32 views

Calculate best area with overlaying multiple layers buffer shapes

I am using QGis and I have a set of 20 layers with buffers. I'm interested in where they overlap most and I want to create a single layer that shows which are the places where they overlap most and ...
0
votes
1answer
42 views

Graduated colouring Voronoi polygons? (QGis)

I've got a huge database of depth points for the whole Irish sea which I'd like to be a nice smooth surface, or at least have a depth value associated with the entire area (i.e. include the ...
0
votes
0answers
37 views

QGIS 2.0.1: Changing layer properties with python console

I'm working on a plugin that will aim to ensure that the following steps either "transparent" to the user with one click :   Creating a table with predefined fields Record in this table in postgis, ...
0
votes
0answers
57 views

how do I add attribute features to an attribute table which already exists?

Using Verson 2.0, downloaded as normal. I have an ESRI shapefile of my road map for 2006. I have a paper map of roads for 1969. I want to see what roads have been built between 1969 and 2006 (none ...
2
votes
1answer
172 views

how to fix greyed out edit button

I created a QGIS map, which I was able to edit (right click on layer and select toggle edit, or use button in tool bar). Having returned to work on the plan, most layers now have this button greyed ...
1
vote
0answers
81 views

How to add a MSSQL spatial layer using Python?

I'm having difficulty adding a MSSQL spatial data layer using Python. The database is password protected, and I can add the layer without any problems using the built in feature, but I can't make it ...
0
votes
1answer
157 views

How to zoom to the extent of Qgsvectolayer qgis?

Anyone know how to zoom to the extent of a Vectorlayer in qgis using python plugin?
1
vote
0answers
44 views

qgis 1.8.0 crash when starting qthread

I am trying to update a vector layer attribute table using QThread. i connect a pushbutton click with a slot to start the thread: def EGSupdateAttributeTable(self): AttUpdateEGSThread = ...
0
votes
0answers
65 views

how can i read an attribute value from qgsfeature?

How can i read an attribute value from qgsfeature ? i am trying to update some attribute using other and i have to read value from attribute in the qgsfeature . my source code: provider = ...
0
votes
0answers
32 views

What is the action name in qgsinterface for the deselect feature from all the layer tool?

I want to add the deselect feature from all the layer tool in the toolbar when the qgis user start editing a vector layer. anyone know what is the name of this action in qgis api 1.8?
1
vote
1answer
125 views

How to activate a layer in QGIS layers legend

How can I activate a layer in qgis map legend automatically using python code . I am using qgis.utils.iface.setActiveLayer(self.theLayerToEdit) but the layer is still not checked in the maplegend. ...
1
vote
1answer
97 views

How to convert format and CRS of many shapefiles to kml (or csv, json..)?

I tried to use QGIS to transform shp files in kml and to translate the CRS to use in a google maps application. My problem is that I have a lot of shp files that i can open in a bulk manner by drag ...
2
votes
1answer
70 views

Can I Turn Off or Remove Map Layers in QGIS Print Composer

The title pretty much says it all. I have a base map in QGIS that I am using with several Print Composers. In one of the Print Composers, I don't want one of the layers to show up. Is there any way ...
1
vote
0answers
33 views

How to search for layers in the layers panel?

I have QGIS projects with a lot of layers. Sometime it's difficult to find a layer into Layers Panel. How to search it?
4
votes
1answer
55 views

QGIS 2 bold Layer names?

I am currently working with QGIS 2.0 in an Ubuntu environment. I have a quite large project with many different layers and layer-groups. By default the layernames are in bold fonts and the groups are ...
0
votes
1answer
160 views

How to set style in the database (QGIS)

Is it possible to set style layers in the database? (QGIS) [MySQL database] I would like to set and share my style to other users when they open the layer it's still as my style. Thank you
1
vote
2answers
63 views

Error adding a delimited text layer

Im working with QGIS 1.8.0 and I have been trying to upload a delimited text layer but keep getting the following error : The layer ...
2
votes
1answer
73 views

Unable to change the layer unit in QGIS

I have been working with QGIS for 2 weeks and I got the hang of it now. The problem now is I cannot calculate the area of a created polygon. Because the layer unit is not changing to meters. When ...
0
votes
1answer
121 views

Error 'Invalid geography. Antipodal edge…' with Postgis

I have a table in postgis like this CREATE TABLE locations (id int, name VARCHAR(255), pos geography(POINT, 4326)); with a couple of points. E.G. INSERT INTO locations (name, pos) VALUES ...
0
votes
0answers
90 views

How to create a Layer from a list of points in PyQgis

I`ve developed an algorithm that generated an two dimensional array with points. Each subList of this array must be displayed as an polygon on the map view, and the recently created Vectors should be ...
0
votes
1answer
84 views

Deleted layers still appear while loading project QGIS 1.8

I'm working on a project where I digitized a few maps (georeferenced) and I also added a couple of csv files. I deleted the raster and cvs layers after I included them into the project as shapefiles ...
0
votes
0answers
45 views

Is there a way to create read-only layers?

I have a project in QGIS with several views loaded from a postgis-database. Editing and creating new objects in these layers won't work (because they are views) and it would be easier if the user ...
0
votes
1answer
98 views

how to make transparent layers with Google earth layer?

with your help, i solved most of my problems, but here is another one - i guess, a smaller issue... I managed to get Google earth layer, but when I add my GPS gpx files, are all hidden under the ...
0
votes
0answers
96 views

QGIS layers not adding properly

using QGIS 1.8.0 lisboa on windows 7 pc adding vector layers and they are not adding properly they don't show up in the layers list but they are there when I happen to merge the the layers ...
1
vote
1answer
84 views

How to sum the values for bins with the same location?

I have two maps in csv form, each has a latitude, longitude, and value column. Since not all the positions in one map are in another map, is there any way in QGIS to display a new map which only shows ...
0
votes
0answers
41 views

How can I import layers into a database?

According to the QGIS User Guide (release 1.8.0, page 203/204) I only have to drag a layer from the QGIS Browser to the DB Manager. But for me this does not work.
0
votes
1answer
275 views

QGIS python - reference a layer in the table of contents

I'm trying to create a plugin for QGIS using python, But need some help. I want to 1.Zoom to a layer and 2. make the layer visible(switch off or on). But I have managed to zoom to an active layer by ...
1
vote
1answer
95 views

Rendering order of layers in QGis libraries

I am using the QGis libraries in a external Qt App. When adding vector and raster layers (in any order) to the QgsMapLayerRegistry instance, it somehow sorts the layers so that the vector layers is ...