# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1508001043 -7200
# Node ID cadb986c2dec16692e0bf563b06eaf1352b5badc
# Parent  644b7e2590595de06a964a3c949465d0d0fad573
Added a function that identifies overlapping periods within a collection.

diff -r 644b7e259059 -r cadb986c2dec imiptools/period.py
--- a/imiptools/period.py	Sat Oct 14 19:10:09 2017 +0200
+++ b/imiptools/period.py	Sat Oct 14 19:10:43 2017 +0200
@@ -408,6 +408,31 @@
     overlapping.sort()
     return overlapping
 
+def get_overlapping_members(periods):
+
+    "Return members of the 'periods' collection that overlap with others."
+
+    if not periods:
+        return []
+
+    l = periods[:]
+    l.sort()
+
+    overlapping = []
+
+    last = l[0]
+    last_added = None
+
+    for p in l[1:]:
+        if p.get_start_point() < last.get_end_point():
+            if last_added != last:
+                overlapping.append(last)
+            overlapping.append(p)
+            last_added = p
+        last = p
+
+    return overlapping
+
 # Period layout.
 
 def get_scale(periods, tzid, view_period=None):