[postgis-tickets] [SCM] PostGIS branch master updated. 3.3.0alpha1-3-g75e2cdc5c
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- Log -----------------------------------------------------------------
commit 75e2cdc5cbc05205a47bbb6bf2be96b84ca55c9c
Author: Martin Davis <mtnclimb at gmail.com>
Date: Sun May 22 10:47:56 2022 -0700
Improve doc for ST_LineMerge
diff --git a/doc/html/image_src/Makefile.in b/doc/html/image_src/Makefile.in
index bb8ea0d47..175685c2e 100644
--- a/doc/html/image_src/Makefile.in
+++ b/doc/html/image_src/Makefile.in
@@ -102,6 +102,8 @@ IMAGES= \
../images/st_linecrossingdirection04.png \
../images/st_line_interpolate_point01.png \
../images/st_line_interpolate_points01.png \
+ ../images/st_linemerge01.png \
+ ../images/st_linemerge02.png \
../images/st_line_substring01.png \
../images/st_locatebetween01.png \
../images/st_longestline01.png \
diff --git a/doc/html/image_src/st_linemerge01.wkt b/doc/html/image_src/st_linemerge01.wkt
new file mode 100644
index 000000000..d9fc0eb3b
--- /dev/null
+++ b/doc/html/image_src/st_linemerge01.wkt
@@ -0,0 +1,2 @@
+ArgA-arrow;MULTILINESTRING((10 160, 60 120), (120 140, 60 120), (120 140, 180 120))
+Result-endpoints;LINESTRING(10 60, 60 20, 120 40, 180 20)
diff --git a/doc/html/image_src/st_linemerge02.wkt b/doc/html/image_src/st_linemerge02.wkt
new file mode 100644
index 000000000..e6c960e7f
--- /dev/null
+++ b/doc/html/image_src/st_linemerge02.wkt
@@ -0,0 +1,2 @@
+ArgA-arrow;MULTILINESTRING((10 160, 60 120), (120 140, 60 120), (120 140, 180 120), (100 180, 120 140))
+Result-endpoints;MULTILINESTRING((10 60, 60 20, 120 40), (120 40, 180 20), (100 80, 120 40))
diff --git a/doc/reference_processing.xml b/doc/reference_processing.xml
index db32d5fd9..bd5135038 100644
--- a/doc/reference_processing.xml
+++ b/doc/reference_processing.xml
@@ -1193,35 +1193,68 @@ FROM test;
<title>Description</title>
<para>Returns a LineString or MultiLineString formed by joining together
- the constituent line work of a MultiLineString.
+ the line elements of a MultiLineString.
Lines are joined at their endpoints at 2-way intersections.
Lines are not joined across intersections of 3-way or greater degree.
</para>
- <note><para>Only use with MultiLineString/LineStrings. If you pass a Polygon or GeometryCollection into this function, it
- returns an empty GeometryCollection</para></note>
+ <note><para>Only use with MultiLineString/LineStrings. Other geometry types
+ return an empty GeometryCollection</para></note>
<para>Performed by the GEOS module.</para>
<para>Availability: 1.1.0</para>
- <warning><para>This function will strip the M dimension.</para></warning>
+ <warning><para>This function strips the M dimension.</para></warning>
</refsection>
<refsection>
<title>Examples</title>
+ <para>
+ <informalfigure>
+ <mediaobject>
+ <imageobject>
+ <imagedata fileref="images/st_linemerge01.png" />
+ </imageobject>
+ <caption>
+ <para>Merging lines with different orientation.
+ </para>
+ </caption>
+ </mediaobject>
+ </informalfigure>
+ </para>
<programlisting>SELECT ST_AsText(ST_LineMerge(
-'MULTILINESTRING((-29 -27,-30 -29.7,-36 -31,-45 -33),(-45 -33,-46 -32))'
+'MULTILINESTRING((10 160, 60 120), (120 140, 60 120), (120 140, 180 120))'
));
-st_astext
---------------------------------------------------------------------------------------------------
-LINESTRING(-29 -27,-30 -29.7,-36 -31,-45 -33,-46 -32)
+--------------------------------------------
+ LINESTRING(10 160,60 120,120 140,180 120)
</programlisting>
+
+ <para>
+ <informalfigure>
+ <mediaobject>
+ <imageobject>
+ <imagedata fileref="images/st_linemerge02.png" />
+ </imageobject>
+
+ <caption>
+ <para>Lines are not merged across intersections with degree > 2.
+ </para>
+ </caption>
+ </mediaobject>
+ </informalfigure>
+ </para>
+ <programlisting>SELECT ST_AsText(ST_LineMerge(
+'MULTILINESTRING((10 160, 60 120), (120 140, 60 120), (120 140, 180 120), (100 180, 120 140))'
+ ));
+--------------------------------------------
+ MULTILINESTRING((10 160,60 120,120 140),(100 180,120 140),(120 140,180 120))
+</programlisting>
+
<para>If merging is not possible due to non-touching lines,
the original MultiLineString is returned.</para>
<programlisting>
SELECT ST_AsText(ST_LineMerge(
'MULTILINESTRING((-29 -27,-30 -29.7,-36 -31,-45 -33),(-45.2 -33.2,-46 -32))'
));
-st_astext
----------------
MULTILINESTRING((-45.2 -33.2,-46 -32),(-29 -27,-30 -29.7,-36 -31,-45 -33))
</programlisting>
@@ -1230,7 +1263,6 @@ MULTILINESTRING((-45.2 -33.2,-46 -32),(-29 -27,-30 -29.7,-36 -31,-45 -33))
SELECT ST_AsText(ST_LineMerge(
'MULTILINESTRING((-29 -27 11,-30 -29.7 10,-36 -31 5,-45 -33 6), (-29 -27 12,-30 -29.7 5), (-45 -33 1,-46 -32 11))'
));
-st_astext
--------------------------------------------------------------------------------------------------
LINESTRING Z (-30 -29.7 5,-29 -27 11,-30 -29.7 10,-36 -31 5,-45 -33 1,-46 -32 11)
</programlisting>
-----------------------------------------------------------------------
Summary of changes:
doc/html/image_src/Makefile.in | 2 ++
doc/html/image_src/st_linemerge01.wkt | 2 ++
doc/html/image_src/st_linemerge02.wkt | 2 ++
doc/reference_processing.xml | 52 ++++++++++++++++++++++++++++-------
4 files changed, 48 insertions(+), 10 deletions(-)
create mode 100644 doc/html/image_src/st_linemerge01.wkt
create mode 100644 doc/html/image_src/st_linemerge02.wkt
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