Tagged Questions

0
votes
0answers
22 views

How to change value of an Line edit dynamically

I create a form in QT4 and compile with pyuic4. it create an form.py I want to modify the value of the line edit dynamiclly with code. I put this code in the form.py but never happen: ...
0
votes
1answer
50 views

Make many lines in one layer (Python)

I what to create many lines with this code: v_layer = QgsVectorLayer("LineString", "cable", "memory") pr = v_layer.dataProvider() seg = QgsFeature() ...
0
votes
1answer
92 views

How can I create a line with three points with Python in QGIS?

I'm new to Python and I'm having some dificulties. I want to create a simple layer with a line in the console of QGIS with Python. How can I do that?
-1
votes
1answer
84 views

QGIS and Python - create line with multiple points in postgis

How can I create a line, with Python functions, with many points that are records in Postgis? Thank you
0
votes
1answer
72 views

In QGIS can I show just the lines in a Postgis query? How can I do that?

I have three tables in Postgresql, each table with one layer of lines. I want to show the path of an initial line to another final. Is it possible executing a SQL query? Thanks My three tables are ...
0
votes
1answer
85 views

Problems using v.split in SEXTANTE toolbox to split lines

I got this error： Or don't click "open output file after running algorithm", but there is no new shapefile created on my desktop. How to solve this problem and split lines at a specified distance？ ...
3
votes
1answer
133 views

How to split line at a specified distance and getting coordinates of start and end points of each line segment？

I tried v.split in GRASS： and my notebook ran a lot of time but showed this error：bad allocation, then I click "OK", and got nothing. Are there other ways to split lines？and I hope to get 2 new ...
0
votes
0answers
30 views

How to determine if a line is within a polygon or if it exceeds the polygon boundaries?

So I have a polygon layer and a line layer and a point layer... Each line goes to the centroid of 1 polygon, some of those lines come from within the same polygon, some come from outside of that ...
2
votes
1answer
97 views

How does Flow Mapper Plugin work?

I downloaded the Flowmapper plugin for Qgis and I can't seem to find any information on how it is supposed to work... Also the text seems to cut-off and not fully showing for the input fields so I'm ...
3
votes
1answer
264 views

How do I find vector line bearing in QGIS or GRASS?

How can one extract the bearings from a set of lines in a vector file? I'm trying to find the bearings of several straight vector line segments (simplified contour lines, actually) and can't figure ...
4
votes
1answer
90 views

How change border line to no pen with python console?

From Python console I load a shapefile with qgis.utils.iface.addVectorLayer. How I can remove border lines (change to no pen) in the active layer?
1
vote
2answers
120 views

Selecting lines occupying identical positions in MapInfo or QGIS

I have two shapefiles from a client, one is their entire network (complete with unique IDs) and another a selection I need. However the selection file does not have unique IDs but the entire one does. ...
2
votes
1answer
84 views

Sum line length with clip intersect? [closed]

SELECT sum(st_length(st_intersection(POLY.geom, LINE.geom))) AS sum_line_length... Is this function OK to calculate the sum of lines length? Wonder if it do the clip line where one line go from one ...
13
votes
2answers
289 views

How can I merge/collapse nearby and parallel road lines (eg. a dual-carriageway) into one single line?

I have a shapefile from OSM which contains all the roads within a city. Larger roads (like dual-carriageways) seem to have 2 parallel lines. I'd like to collapse / combine those into 1 line so I can ...
7
votes
2answers
490 views

Elevation profile 10 km each side of a line

How can I get an elevation profile for a band of terrain? The highest elevation within 10 km (on each side of the defined line) should be taken into account. I hope my question is clear. Thank you ...
6
votes
1answer
161 views

QGIS line style

I found the latest QGIS has a great tool to create complex styles, however looks like one small but very useful thing is missing, or I can't find it. I'm trying to create a line style something like ...
1
vote
0answers
117 views

Creating points along lines? [duplicate]

Possible Duplicate: How to create a point along a line given distance How to create equidistant points in QGIS? I have some road survey data and each line has an individual value and ...
5
votes
0answers
99 views

Moving points onto lines (~neighborhood)

I do have two vector layer, of which one is a point layer based on "events" by remote sensing and the second one is a line layer from local research. In my case these are earthquakes and tectonic ...
2
votes
0answers
50 views

Strange line appearing

I have this line in my project's layer which i cant make disappear: I hope you can see it. In QGIS is much more visible. An it also appears on the print composer. Any suggestions would be very ...
3
votes
0answers
79 views

Why doesn't Polygonizer copy the line ids to my polygonized shapefile?

I am trying to convert a line shapefile into a polygon shapefile using Polygonizer plugin, and when my new polygons are created all the cells in my id field are "Null", although I have clicked "copy ...
3
votes
1answer
120 views

How to create a line with start and end points which are in another layer in QGIS?

In my map, there are lots of points in layer A. I want to make a line layer B and I want to make start & end points of lines snapping to points in layer A manually. Can I use points of layer A as ...
6
votes
1answer
363 views

How to connect places (points) without crossing lines?

I have two sets of data. One with placemarks represented by blue dots in image below, and another set of geographic data with lines represented by grey lines. 1) For the first point in drawing, I'm ...
5
votes
4answers
209 views

How to avoid holes in polygons from lines?

I am trying to convert a dataset of lines that contains the coast of New Zealand into a big polygon. However using the vector -> geometry tools -> lines to polygon command in Quantum GIS results in a ...
3
votes
3answers
366 views

Finding centrelines from polygons?

I was wondering if there is a way to create centre lines from polygons in QGIS? I have a polygon layer, but ideally need the centrelines as a separate file. Thanks, Alan
4
votes
2answers
318 views

How to find isolated geometry/attributes in road network?

I have a road network with paved/unpaved status in attribute table. This road network don't must contain isolated paved geometry. There are any solutions find isolated geometry in GIS software ...
2
votes
1answer
524 views

Basic User Questions: Tracing a Border in QGIS

The project: I'm plotting a dilapidated cemetery, I'm using GPS waypoint data to plot the headstones in QGIS. The map I'm making is to show the orientation of the graves, and who is in them. I ...
1
vote
1answer
366 views

Splitting lines at a specified distance

Does exist some plugin with it is possible to Splitting lines at a specified distance in Qgis?
4
votes
1answer
575 views

Is there a way to automatically snap loose points of lines to close by vertices with Quantum GIS?

I have a vector layer of lines that were drawn with the snapping option off. I need to have them snapped but, there are hundreds of lines. Is there any solution to do this automatically or ...
3
votes
2answers
757 views

Workflow for creating line features between two coordinate pairs in QGIS

I have a table of stream reaches with xy coordinates for their respective tops and bottoms. I'd like to convert the table to a feature, using the xy coordinates as the endpoints of the line. Any ...