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I have a road network (line layer). I am trying to get list of coordinates (Lat,Long) from road network in the form of geometry LINESTRING as shown below. However, I am only getting two coordinates as shown in second figure.

enter image description here

What I have tried:

lyr = iface.activeLayer()
fl = ['lat','lon'] #Add these fields before executing code

with edit(lyr):
    for f in lyr.getFeatures():
        p = f.geometry().centroid().asPoint()
        _=f.setAttribute(f.fields().indexFromName(fl[0]), p.y())
        _=f.setAttribute(f.fields().indexFromName(fl[1]), p.x())
        _=lyr.updateFeature(f)

enter image description here

Case Msee
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    Well, since you're returning the centroid of the line, it's no surprise you only get point coordinates. – Erik Sep 21 '20 at 12:59
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    You use centroid's coordinates. – Kadir Şahbaz Sep 21 '20 at 13:00
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    I am not sure if I understand what you try to achieve, but I think the '.asWkt()' function would be helpful:

    for f in lyr.getFeatures(): print(f.aswkt())

     – Sam Sep 21 '20 at 13:01
  • @Erik. What is the best way to extract coordinates(Lat,Long) from line layer? – Case Msee Sep 21 '20 at 13:15
  • @KadirŞahbaz. What are the other options please? – Case Msee Sep 21 '20 at 13:15
  • @Sam. Instead of print, can we save Wkt()' function coordinates in the line layer? – Case Msee Sep 21 '20 at 13:17
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    @CaseMsee You mean to store it as an attribute? sure! I recently used this question to edit a feature's attributes. You can create a new string attribute and edit it with the value of "f.geometry().asWkt()" – Sam Sep 21 '20 at 13:24

1 Answers1

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First, add a field (name: geometry, type: string, length: 1000 keep it long). Then use the following script:

lyr = iface.activeLayer()

with edit(lyr):
    for f in lyr.getFeatures():
        f["geometry"] = f.geometry().asWkt()
        lyr.updateFeature(f)
Kadir Şahbaz
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    Great answer. The only thing is: the above code produces MULTILINESTRING geometry in the attribute table. Is it possible to convert MULTILINESTRING to LINESTRING as shown in first image of question? – Case Msee Sep 21 '20 at 13:32
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    Your layer probably contains multilinestrings. Use Convert geometry type tool in Processing Toolbox to convert to Linestring before. – Kadir Şahbaz Sep 21 '20 at 13:37
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    Thank you. This is what I was thingking. Is it possible to plot MULTILINESTRING coordinates in the QGIS? Mapping XY coordinates are simple but I was wondering about MULTILINESTRING coordinates – Case Msee Sep 21 '20 at 13:38
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    You can ask another question about it. QuickWKT plugin may help. I don't understand what exactly you mean. – Kadir Şahbaz Sep 21 '20 at 13:42
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    Only an advice: I wrote the same but instead "geometry" I wrote 'geometry' and it has worked! – Paulo Matias Montecinos Medel Dec 15 '22 at 08:42
  • @PauloMatiasMontecinosMedel Typically, either single or double quotes can be used interchangeably in Python. – Kadir Şahbaz Dec 15 '22 at 12:45