QGIS is a user-friendly, cross-platform GIS application licensed under the GNU General Public License.

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54 views

Copy parts from several attribute tables in shapefiles?

I have several shapefiles from which I wish to take parts from their attributes tables to make a new attributes table. Is this possible without destroying the original attributes table? I have ...
3
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1answer
32 views

QGIS: Plot a layer given with Longitudes [0 360] to [-180 180]

I have a world map in correct Longitudes from -180° to 180°. Additionally, I have a shapefile of data from South America, which shows at 290° instead of -70°. How can I reproject it using QGIS?
3
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1answer
36 views

Changing attribute values in a memory layer

I'm trying to change attribute values in a memory layer. My memory layer is defined in this way: pro.addAttributes([QgsField("nom", QVariant.String), QgsField("valeur", QVariant.Int)]) I made ...
2
votes
1answer
131 views

Highest DEM pixel in polygon

I'm working with QGIS and have a big DEM raster layer with height information and a vector layer with many polygons, representing 1 x 1 degree tiles. Now I want to find for every polygon the highest ...
2
votes
1answer
51 views

Clip in QGIS 2.4.0 resulting in empty output files

I'm seeing the same problem to Clip or Intersection tool - QGIS giving empty files trying to use the Clip tool since upgrading to QGIS 2.4.0, but have not been able to fix the problem based on the ...
2
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1answer
14 views

QGIS raster clip error: Cutline not of polygon type

I have a raster file and want to clip it, but I'm getting this error: "ERROR: Cutline not of polygon type" what does this error mean and how can I resolve it?
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0answers
29 views

Vector layers without geometry in QGIS?

Using QGIS, I have set up a couple of automated layer additions via the toolbar. After adding geometry in each respective layer (point, lineString, polygon) and saving changes to the layers, the added ...
2
votes
0answers
59 views

Exporting spatialite view to shapefile from QGIS modifies the original data types

We have a spatialite .sqlite database where we have views which are nicely rendered by QGis, with all the symbols and everything!! There are integer fields on the view which are based on fields of ...
2
votes
1answer
49 views

Calculate EVI From Landsat 8 in QGIS [closed]

I have calculated atmospherically corrected reflectance values for Landsat 8. From that, I am getting correct values of NDVI in QGIS, but for EVI I am not getting the correct values. For some images ...
2
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0answers
21 views

Align & Sum Grids in Python

I have two grids. One, call it A, is 4320x2160 cells and spans the whole globe. The other, call it B is 8640x3432 and spans the circumference of the globe, but is clipped toward mid-latitudes. Both ...
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2answers
34 views

QGIS Convert Polygon M to polygon

I have been using Argis 10.1 and been able to convert polygon m to polygon shapefiles. I would like to do this with QGIS but I am having difficulty in finding the correct tool to do so. Please Help
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0answers
66 views

I cannot install QGIS 2.4 on my Windows 7, 64 bit machine

I am running Windows 7, 64 bit and cannot install QGIS 2.4 after several days of trying. I have also tried downloading 2.2 with no avail. I keep getting this error: The text of the error is: ...
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0answers
25 views

QGIS crashes when trying to display features form MySQL

I import shapefiles into MySQL using the following command: ogr2ogr -f MySQL MySQL:GIS,host=localhost,user=root,password=root /home/user/Public/myshape.shp -nln Shape_table -update -overwrite -lco ...
2
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3answers
52 views

How to display a table with more than one geometry column in QGIS?

In PostGIS, it is possible to use addgeometrycolumn more than once on the same table. Example: I have one table "scenes" with many attributes, and 2 geometry columns: the_geom1 and the_geom2. select ...
1
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1answer
58 views

QGIS Relation Manager

I have a PostgreSQL database with a one-to-many relationship. Here is a reduced example: CREATE TABLE buildings.building ( objectid serial NOT NULL, building_no character varying(40) NOT NULL, ...
1
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2answers
53 views

QGis 2.4 - Python 2.7 PyQT4.Qtcore.QStringList Import failed

I receive an import error when trying to import QStringList from the Qgis Python console (or when loading a custom plugin). from PyQt4.QtCore import QStringList Traceback (most recent call last): ...
1
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1answer
18 views

How to set QGIS options in standalone pyqgis application

I have a standalone application which uses the QGS api to view and query map layers. One layer is a WMS-C layer which automatically caches tiles which is great. I want to also activate a setting which ...
2
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0answers
20 views

access point layer representation in qgis with pyqgis

I am exporting the style of a categorized point layer with qgis: unfortunately my code only extract the size of the symbol in the definition of the properties of the layer but not the ...
3
votes
3answers
204 views

How to export polygon coordinates to CSV (not WKT)?

I am new to QGIS, and I am now trying to export polygon coordinates from a shape file to a csv file, but so far all my attempts have failed. I have found numerous questions and answers about this, but ...
3
votes
0answers
34 views

How to export data from sql server into shapefile in the decimal format in QGIS 2.4?

The last couple of days, I have been working on exporting data from SQL to a shapefile in QGIS 2.4. While converting into a shapefile, the data type changes automatically from Float to Integer in the ...
3
votes
1answer
33 views

How can units be defined in QGIS for the Rasterize tool?

I am using QGIS 2.4 (Chugiak) via the kyngchaos build for OS-X. My question is--when using the Rasterize tool to convert a point vector layer to a raster and using the "Raster resolution in map units ...
1
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1answer
24 views

How to add dashed line in QGIS print composer

I want to display two maps in the print composer: a main one, and another showing a zoomed in section of the main map. I've drawn a rectangle over the original region and want to add two dashed lines ...
2
votes
1answer
50 views

How to find and replace a singe word in a string?

How do i find and replace a single word of a string? e.g. Calle Iparraguirre to Iparraguirre I've tried: replace( 'Calle\\s', 'Calle\\s', '') replace( "name",'calle','') and all combinations ...
1
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1answer
35 views

Coordinate System changes after reprojection

I have changed the projections of some Natural Earth Shapefile to "WGS 84/Pseduo Mercator", that works fine (after cutting out the artic), but now the co ordinates of the shapefile are all out of ...
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0answers
26 views

How to set a defined distance between nodes to digitize in qgis?

Using QGIS (by now I have the 2.4 version) I would like to set some parameter (I don't know if such exists) that would impose a definite or maximal distance between nodes when digitizing a polyline or ...
1
vote
1answer
21 views

PyQgis Message Bar Woes [closed]

Having a bit of trouble with the basics of getting the (awesomely discreet) new user prompt/warning to properly display. Here is the (troubled) code I am using: self.iface ... ...
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0answers
76 views

Many problems with QGIS processing

I'm having a lot of problems with QGIS processor. Most of the algorithms show me this QGIS log error: La fuente de datos no es válida. (Data source not valid) This happens with SAGA and GRASS ...
0
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1answer
47 views

PyQGis - Working with Spatialite

I wrote a Vector layer to a spatialite file/db using the dedicated API tool, using valid driver names supported formats by OGR. When connecting to that db, I can't retrieve properly the geometry ...
2
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0answers
25 views

Is it possible to drag&drop line precisely 6 meters to right or left?

I use Quantum GIS 2.2.0 Valmiera I have a polyline layer. I can drag&drop polyline nodes by using "Node Tool". Is it possible to drag&drop line precisely 6 meters to right or left?
0
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0answers
15 views

Adding attributes to a hexagonal grid generated with MMQGIS

I generated a hexagonal grid with MMQGIS, and I need to add some attributes to each hexagon. Is there a convenient way to do this or I have to work with the dbf file? In that case, what is the meanign ...
2
votes
1answer
31 views

A way to transform by special epsg-code

In my country, we have a special epsg-code for transformation (#4649). In the definition ...
1
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1answer
45 views

Shapefile not projecting correctly [duplicate]

I am still new to this, so I apologise if I don't make a lot of sense! I am using QGIS 2.4.0 Chugiak. I am working on a project set to the GDA94/MGA Zone 50 coordinate system with 'on the fly ...
3
votes
1answer
81 views

Where can I find information about the development history of QGIS?

I know very little about early versions of QGIS (far far away from now..) and i'm feeling curious :-) I am looking for various information about the past of QGIS, including: Do you know in what ...
1
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0answers
29 views

Way to split and create buffer space between polygons in QGIS or ArcMap

After performing a feature extraction of rooftops, some of my buildings have been joined together as one polygon. I want to split these large polygons so that each new division is only covering one ...
3
votes
0answers
32 views

Looking for a QGIS solution to make aerial imagery ArcSDE compatiable

Would like to avoid having to use 3d Analyst and use free raster tools in QGIS or elsewhere to make aerial rasters ArcSDE compatible. This 18 page work flow is what I am trying to use. Any suggestions ...
1
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0answers
13 views

Vector Layer Symbol (ism) properties?

I would like to streamline the render of a polygon grid vector layer as a simple line (no fill) via Python coding. I am I bit confused by the implementation referenced by the API. Is it possible to ...
1
vote
1answer
23 views

How to test for multiple map items in Composer using python?

I am building a QGIS plugin and I need to check for multiple maps items in Composer that works on all platforms. Currently I am getting the first map in the composition using the code below, but ...
0
votes
0answers
21 views

Grass extension from within OSGeo QGIS

It is not clear to me how the connection between GRASS and QGIS works. I am aware about GRASS plugin, GRASS tools in processing toolbox and GRASS GUI which comes with OSGeo installation. By default I ...
3
votes
1answer
93 views

Benchmarking QGIS and ArcGIS for Desktop speed for “significant buffer on very large shapefiles”?

I am a newcomer to the world of GIS. I realized that QGIS was relatively similar to ArcGIS for Desktop. I would like to know if the two programs are comparable in terms of computational speed. For ...
4
votes
1answer
108 views

QGIS 2.2 - possible to do a JOINS from the Action list?

I have a set of layers that need to be joined (Layer Properties > Joins) to one specific layer. The reason for this is that I will be updating and adding new layers into my project and would like a ...
2
votes
2answers
50 views

Is it possible to decrease detail level (decrease file size) in Spatialite OSM export?

I currently use Spatialite exports from OSM data (together with Google maps like styles by Underdark) which are very useful for me as the files are easily portable with the project and I do not need ...
3
votes
2answers
89 views

How to set the Identify Feature tool in QGIS 2.4?

The Identify Results window does not appear when using the identify feature tool in QGIS 2.4. I guess there's a check box somewhere I need to check/uncheck, but the settings of the tool changed ...
1
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0answers
26 views

How to export data from sql database in the decimal format in QGIS?

Currently I am working with QGIS and fetching data from SQL server and export it in the format of shapefile in QGIS. While importing the data from sql server attribute table showing data with ...
1
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0answers
22 views

Compiling QGIS for Slackware (Slak 14)?

I use a Slak 14 box and tried to install QGIS on it. the compile process goes on for 30 minutes or so (dual Xeon 3.2 ghz) and then I get the errors below. Says the compiler doesn't work. Have had no ...
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0answers
25 views

How to make crs transformation of a QgsVectorLayer?

I need to transform QgsVectorLayers in python from one crs into another crs. By googling I found the following solution ...
3
votes
3answers
79 views

How to count polygons in multipart features?

I'm trying to count the number of polygons in a multipart feature. My aim is to have a 'count' attribute to quantify fragmentation of multipart land parcels. I've looked at the field calculator and ...
1
vote
1answer
41 views

How to automatically connect point [closed]

I have to draw all the rows connecting the 2 edges with a line. It's not so hard to it manually, but it takes a lot of time. Is there a way to connect the two edges of the rows automatically? For ...
3
votes
1answer
33 views

Why is the SelectionChanged signal triggered every time i click on the layer?

i'm making some experiments with the SelectionChanged signal of a QgsVectorLayer. i try this piece of code : curLayer.selectionChanged.connect(self.test) and "test" print a warning message. The ...
1
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0answers
33 views

How to programmatically interrupt QGIS initialization and startup

I'm wondering how to interrupt the initialization of QGIS 2.0 on Windows XP before start up. I've put a dialog in one of my plugins that shows up on start up. However, I'd like to make a quit button ...
2
votes
0answers
44 views

Saving/Loading QGIS style .qml and avoid specified symbology

Is it possible to save QGIS styles without the symbology style? This may seem like a strange question, but I am trying to automatically set the ValueMap widget under layer properties via a plugin for ...