Is it possible to convert a polygon to polyline in QGIS WITH the adjacent polygon IDs for each polyline segment? I know one can do this in ArcToolbox but need to find out how to do it in QGIS.
It was not clear to me if the question was about a single QGIS tool to do the tasks to [A] convert a polygon to polylines, and [B] return a measure to describe which polygon is adjacent to one another, all at once.
This is an ad-hoc response assuming the mentioned ArcTool is
Polygon Neighbors tool, hence about the task [B] only.
Polygon neighbors tool can work for cases of
Edge adjacent and
Node adjacent - polygons can be attached to each other at edges or at nodes:
(1) Edge adjacent relationships - YES, there is Shared polygon edges tool
Red polylines on the attached image (below) is an output of QGIS Processing Toolbox -
SAGA | Vector polygon tools | Shared polygon edges.
The associated attribute table is like below, which shows adjacent polygon IDs:
(2) Node adjacent polygons - Probably NOT
As shown in the above image, Polygon 1 and Polygon 6 share the part of their edges but not completely. ArcToolbox tool may report back this case as a
Node adjacent (please correct me if I am wrong). This is rejected by
QGIS - SAGA / Shared Polygon Edges tool.
If this meets your selection criteria (I mean, if it is how do you want them to be adjacent), this tool can be helpful.