Questions tagged [qgis-3]

for questions specific to the 3.x series of QGIS.

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2
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0answers
12 views

Sharing classes and methods code among processing scripts

I am writing a set of processing scripts for seismic data acquisition (2D and 3D) planning and geometry processing. They are very crude scripts (I'm not a developer) that performs the tasks I meant ...
2
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1answer
58 views

How to display the correct unit of measure in PyQgis?

Within a plugin I am developing I select features and for each line feature selected I get the feature distance using: distance.measureLength(feature.geometry()) I also get the total length at the ...
1
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0answers
51 views

How to retrieve text from a QLineEdit in a tabifyDockWidget

I've write a plugin that calls a tool when a certain push button in my tabifyDockWidget is clicked. When the comboBox button is clicked it works perfectly carring the comboBox.currentText() to the ...
2
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1answer
48 views

Why does QGIS convert IntegerLists into something strange and how do I process these in PyQGIS?

I have GeoJSON data which has an integer list and I'd like to query that list in QGIS via GUI (select by expression, visualization) and probably later with PyQGIS. The problem is that QGIS recognizes ...
5
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3answers
221 views

PyQGIS using selected layer from a combobox

With PyQGIS 3, I defined a comboBox to list layers from a QGIS project. I want to use the selected one to execute a treatment. I tried comboBox.currentData() class but it doesn't seem to be the good ...
1
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0answers
38 views

Rotating vector grid in QGIS 3.10 vs 3.8

Just wondering if anyone else has had an issue with vector rotation via the advanced editing tools in 3.10? I have a vertical grid overlaying Vancouver Island that I had tried to rotate using the ...
5
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3answers
96 views

Making curved stroke shape of polygon

I have a lot of polygons representing Forest land use type. Is it possible to style these polygons in such a way like on this picture? Example polygon I have now: So the polygon doesn't have edges, ...
2
votes
1answer
36 views

Setting label colour based on a field value?

I have created a shapefile with lines which I use to place labels exactly where I want them relative to map features. The shapefile has a field for the name that will appear as the label and also a ...
2
votes
1answer
26 views

pyqgis create layer from a list of points

I am working with pyqgis in QGIS3 and i want to create a point layer from an intersection beetween a point and a polygon layer. I can identify wich points intersects my polygon layer but i can't use ...
1
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0answers
14 views

Add python modules so scriptrunner will find them for QGIS on Mac

I am using QGIS 3.10, and Mac OS 10.(14 & 15) This issue relates to recent versions of QGIS for the Mac that are distributed as .dmg. These versions of QGIS bundle their chosen version of Python ...
4
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1answer
97 views

Processing toolbox not working in QGIS 3.4.13

The processing toolbox stopped working in the previous QGIS 3 ltr version I had installed. Now installed 3.4.13 but processing toolbox still not working. I've tried changing the GRASS path without ...
4
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1answer
48 views

How to edit a processing tool in QGIS

Is it possible to make a copy of a tool from the Processing Toolbox in QGIS and make edits to it? As an example, I would like to make a copy of the Import geotagged photos tool and then edit the code ...
1
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0answers
64 views

Linear extrapolation of points using QGIS

I am currently working with hurricane data from NOAA’s IBTrACS. Each gathered data point is separated by three hours. The points and lines can be found in two different data sets on the IBTrACS ...
3
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1answer
38 views

Create rotated point grid inside polygon

I want to create a rotated grid inside a polygon using a starting point and a rotation angle. I have started with the python script found here. I have altered the original script to accommodate ...
1
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0answers
49 views

Determining if layer is visible using PyQGIS

I am working on a plugin 'Stripchartdrawer' current commit https://github.com/sickel/qgisstripchart/tree/ba3afd7184e33331b5af38111e91dbb9b6a2d1c0. One of the features in this plugin is to be able to ...
0
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0answers
35 views

Downloading QGIS for Mac OS?

My mac is too old to install the latest OS which seems to be required for the QGIS complete package. I want to use QGIS 3.4 for Mac OS x 10.11 (El capitan). Is there a download available for this?
1
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0answers
15 views

Missing some polygons while clipping

I keep on missing some polygons while clipping a gdb file with a circle (shape file). I guess it comes from the "invalid geometry" error I get but do not know how to get rid of it.
1
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1answer
37 views

Set size of points independent from map scale

In ArcGIS the size of a point feature is constant independent from the map scale. In QGIS when I zoom in the point get smaller and when I zoom out they get bigger. How can I fix the point size? What ...
3
votes
1answer
100 views

Change text of individual labels

When I have vector layer with several objects and label them, can I change the text of individual labels? I have tried the labeling tools and the tool change label but the field with the label text is ...
0
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1answer
71 views

Separate overlapping labels

I have many point features in close distance to each other and when I label them, the labels overlap. Is there a way that QGIS automatically seperates the lapels from each other and resolves the ...
0
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2answers
107 views

Apply external choropleths in QGIS 3

I have a large number of cloropeths stored in SLD and QML formats. QGis is unable to apply any of those, there is no option in the GUI for SLD, whereas it fails to apply QML files correctly. Is there ...
3
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0answers
28 views

PyQGIS Layout - Change Image Source QGIS 3

Looking for a solution to loop through existing layouts in a QGIS 3.6 document and change a source of an image. The image is the same in each of the layouts. What I have is: from qgis.core import ...
9
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1answer
139 views

Creating vector (with lines/polygons) from raster based on paper map in QGIS

For a task I have several maps created with GIS that look like the following: I am mainly interested in the colored zones that aren't roads (red) or rivers (blue) and would like to turn these into ...
5
votes
1answer
60 views

Matching legend symbology with data driven symbology?

I am tightly bound to a client's CI and fortunately, the data I am working with comes with RGB values in the attribute table. Perfect for data-driven symbology. But how can I (easily) manage to make ...
0
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0answers
13 views

Adding raster Data from Geodatabase to QGIS [duplicate]

I have raster data in a geodatabase and want to open them with QGIS. When I navigate with QGIS to the Geodatabase I get to this window. Unfortunately, I can't open These atx and GDBTABLX files and I ...
7
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1answer
266 views

Debugging QGIS from Visual Studio

I try setup a QGIS debug environment under Windows10 64bit. I followed the instrictions given at https://github.com/qgis/QGIS/blob/master/INSTALL#L423 I also had a look at https://www.shaeffer.co/...
2
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0answers
25 views

How to apply paint effects with PyQGIS?

I would like to apply an inverted polygon style, including opacity and inner shadow using PyQGIS. So far, everything works except for the inner shadow effect. I found in the QGIS API that there is a ...
1
vote
1answer
34 views

Count subset of points in polygons

Being an SQL-noob, I found a working solution to generate a virtual layer with counts of points in the polygons of another layer, inspired by this https://gis.stackexchange.com/a/54680 SELECT ...
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0answers
41 views

QGIS Error with Merging rasters

I'm using QGIS 3.8 with grass . I have 3 rasters that are located far from each other and I would like to merge them into one raster layer. I managed to merge 2 of them but the third one makes ...
2
votes
0answers
44 views

Snapping line layer to line layer

I'm working on a project where I need to snap an existing line layer to a different line layer. These lines represent streams and rivers. I'm working within QGIS Maderia 3.4 LTR. I've tried using the ...
3
votes
1answer
61 views

Return field as array from any map layer in QGIS expressions

In QGIS 3.8 It's obvious in the expression builder how to reference a layer or how to get a feature from a layer but not how to return a whole field from a layer. What expression will return a field ...
2
votes
0answers
47 views

Error while exporting geometry to CSV with MMQGIS

I am importing a DIVA-GIS shapefile into QGIS. It has a lot of polygons on it. My aim is to group different groups of polygons together and dissolve their internal boundaries so that I end up with ...
2
votes
1answer
28 views

Adjusting brightness/contrast for XYZ Tile Data

Is there a way to adjust brightness and contrast for XYZ tile data in QGIS 3.4? Specifically, I'd like to adjust the settings for the Google Imagery Hybrid XYZ tile. I'm running QGIS on Windows 10.
3
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0answers
41 views

“Bring All to Front” is missing in QGIS 3

I am using QGIS 3.4 and 3.10 and a plugin's window ends up hiding behind the canvas. In QGIS 2.10 I had the option "Bring All to Front" to bring all windows to front. Is there an alternative for it ...
2
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0answers
33 views

System couldn't find given path while running v.split

I'm trying to run the Grass Tool v.split and get the following error message: the grayed outline in German translate to "The System couldn't find the given path" The .exe-files of the grass Tools ...
2
votes
1answer
66 views

Maximum and mean value is different in Python than QGIS 3.6

I read a Landsat-8 TIFF file using Python Rasterio to compute the max and mean using the following code: path = "LC08_L1TP_115036_20181025_20181031_01_T1_B7.TIF" test = rasterio.open(path).read() ...
1
vote
1answer
22 views

Tool for adding raster values to vector z axis

In ArcGIS, there is a tool called "Interpolate Shape" which takes a vector layer and underneath a raster. Then it adds the raster grid values to the vectors z-coordinates. Is there a tool in QGIS ...
3
votes
2answers
53 views

Set default style for QGIS Composer Items

When creating a Composer Layout in QGIS, it is useful to add multiple items such as text boxes, shapes and arrows. Once I have formatted an item (eg an arrow line) is it possible to set it as a ...
2
votes
1answer
35 views

Creating a Line feature in PyQGIS QGIS 3.x

In QGIS GUI, a line feature is created from this icon 1.jpg How to Create a line with a fixed distance from a vector layer in python console. This my example: from qgis.core import * from qgis....
2
votes
1answer
56 views

How to connect a QgsMaptool with a widget pushButton

I've write this QgsMaptool above and it works great in python console imports... class obsCreator(QgsMapToolEmitPoint): def __init__(self, iface): self.iface = iface self.canvas ...
5
votes
1answer
85 views

Rule-based labeling with optional second field

I need to label some polygons with 2 fields using only one label: The first being a field in the attribute table named "Bio-Code" the second one being optional if a cell in the field "BBT-Code" is ...
1
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0answers
39 views

QGIS wrong measurments on Google satellite images

I am new to QGIS but I understand the basic principles. I'm working with QGIS 3.8.3 on OpenSUSE Tumbleweed Linux using the KDE environment. Still trying to figure out QGIS, I'm opening a brand new ...
2
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0answers
31 views

Using Python code from QGIS 3.x Graphical Modeler in console?

I want to use "Join Attribute by Location (summary)" processing algorithm in Python console of QGIS 3.10. After design my algorithm process (join sum of field name "abc" form layer 2 (point layer) to ...
6
votes
1answer
247 views

Extracting features with equal field value using graphical modeler of QGIS

Is it possible to automate the following procedure with graphical modeler in qgis 3.4 or is it easier to perform such action with a python script using PyQGIS? Identify a feature (a line) in a vector ...
2
votes
1answer
48 views

Zooming to specific layer using PyQGIS

Using PyQGIS with QGIS 3, I am trying to zoom in a specific layer but I have not succeeded. He tried several answers but it doesn't work for me. Either it gives me a mistake or it does nothing to me ...
0
votes
2answers
62 views

Which versions of python3 can we use with current QGIS3 version

Mac OS 10.04, QGIS 3.10. I have been a way from QGIS for a while and I am now setting up a "new" Mac and having my usual battle with python. Great to see that we now have signed package for QGIS but ...
4
votes
1answer
40 views

Interpolation with Breaklines- How to Apply Breaklines as Surface Discontinuties

I can't seem to get Breaklines to behave as defined here with the QGIS 3 (3.10 today) built-in Interpolation (TIN or IDW) . In my case I am preparing a subsurface structure map with geologic faults (...
0
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1answer
52 views

Designing small letters under words in QGIS

I want to design small letters under words in QGIS when I designed the labels (attach picture). Is there any way to do it?
2
votes
1answer
48 views

Designing text in QGIS

I want to write cubic meters in QGIS 3, I searched a lot but I didn't find any instructions. Is there a way to write cubic meters as m³?
1
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0answers
48 views

How to fill a field with comboBox.currentText()

Basically, I want to create a widget plugin (QGIS 3.x) in which any user can choose a standard text from a combo box and, after press a ok button, enable a layer for editing and calls the add feature ...