Bug report #7980

"Merge connected lines..." doesn't work well

Added by Aren Cambre over 10 years ago. Updated over 10 years ago.

Assignee:Larry Shaffer
Affected QGIS version:master Regression?:No
Operating System:Windows 7 x64 Easy fix?:No
Pull Request or Patch supplied:No Resolution:
Crashes QGIS or corrupts data:No Copied to github as #:16837


The two attached images show two versions of the same view. In one, Merge connected lines to avoid duplicate labels is checked. In the other, it is not checked. Even when checked, there are still a whole lot of label needing merging.

merge_connected_lines.png (399 KB) Aren Cambre, 2013-06-02 07:32 PM

no_merge_connected_lines.png (444 KB) Aren Cambre, 2013-06-02 07:32 PM

detailed_roads.png (114 KB) Aren Cambre, 2013-06-02 07:42 PM


#1 Updated by Aren Cambre over 10 years ago

The plot thickens. The feature may technically be working as intended. See attached. Turns out I have way more in this map in addition to the road's centerline! It's OK to close if someone else agrees with me.

#2 Updated by Giovanni Manghi over 10 years ago

  • Assignee set to Larry Shaffer

are you using the latest master?

#3 Updated by Aren Cambre over 10 years ago

Title bar says 24bffbf.

#4 Updated by Larry Shaffer over 10 years ago

Hi Aren,

So have you been able to verify if it is a bug or not?

Generally, if that function appears to not work right, it may be because adjacent to-be-merged lines do not actually share a point. Not sure if that is exactly how the underlying merge function works, but I don't think it adds to any geometry to fill gaps, i.e. more labels would show up.

#5 Updated by Aren Cambre over 10 years ago

Per the attached file detailed_roads.png, there are in fact multiple parallel-ish lines with the same label (mainlanes, access roads, ramps, etc. of a freeway).

What I wanted was for all of these parallelish lines' labels to be merged, too. I think I was expecting functionality that would actually be a feature request, not a problem with the current feature.

#6 Updated by Larry Shaffer over 10 years ago

  • Status changed from Open to Rejected

I'm not sure such functionality (merging of lines that lie within a specific distance of one another) will ever be implemented as a labeling option.

Seems like some preprocessing of your data with another utility first might be in order, or limiting labeling to just one feature class or feature attribute by using 'Show label' and setting a data defined field or expression. Using a field with 'Show label' allows you to use the Show/hide label' map canvas tool as well (not active with a defined expression) for manually showing/hiding labels (see the tool's tool tip).

I am setting the issue to 'rejected' because that's the only relevant option. Please reopen if you notice a bug with that merge function.

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