# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1417102161 -3600
# Node ID 9d5fb143d88bc0c196afce85a1492a7513fb066e
# Parent  875956967918ab99a97a0683b0b76a447084bdd4
Added functions to arrange periods in a grid/table layout.

diff -r 875956967918 -r 9d5fb143d88b imiptools/period.py
--- a/imiptools/period.py	Tue Nov 25 23:14:03 2014 +0100
+++ b/imiptools/period.py	Thu Nov 27 16:29:21 2014 +0100
@@ -78,4 +78,70 @@
     else:
         return False
 
+# Period layout.
+
+def get_scale(l):
+
+    """
+    Return an ordered time scale from the given list 'l' of tuples, with the
+    first two elements of each tuple being start and end times.
+    """
+
+    scale = {}
+
+    for t in l:
+        start, end = t[:2]
+
+        # Add a point and this event to the starting list.
+
+        if not scale.has_key(start):
+            scale[start] = [], []
+        scale[start][0].append(t)
+
+        # Add a point and this event to the ending list.
+
+        if not scale.has_key(end):
+            scale[end] = [], []
+        scale[end][1].append(t)
+
+    scale = scale.items()
+    scale.sort()
+    return scale
+
+def get_slots(l):
+
+    """
+    Return an ordered list of time slots from the given list 'l' of tuples, with
+    the first two elements of each tuple being start and end times.
+
+    Each slot is a tuple containing a point in time for the start of the slot,
+    together with a list of parallel event tuples, each tuple containing the
+    original details of an event.
+    """
+
+    slots = []
+    active = []
+
+    for point, (starting, ending) in get_scale(l):
+
+        # Discard all active events ending at or before this start time.
+
+        for t in ending:
+            i = active.index(t)
+            active[i] = None
+
+        for t in starting:
+            try:
+                i = active.index(None)
+                active[i] = t
+            except ValueError:
+                active.append(t)
+
+        while active and active[-1] is None:
+            active.pop()
+
+        slots.append((point, active[:]))
+
+    return slots
+
 # vim: tabstop=4 expandtab shiftwidth=4