Implement len() for event.Photons class.

1 files changed, 3 insertions, 0 deletions

diff --git a/event.py b/event.py
index ed64b63..f611edb 100644
--- a/event.py
+++ b/event.py
@@ -42,6 +42,9 @@ class Photons(object):
         flags = np.concatenate((self.flags, other.flags))
         return Photons(pos, dir, pol, wavelengths, t, last_hit_triangles, flags)
 
+    def __len__(self):
+        return len(self.pos)
+
 class Channels(object):
     def __init__(self, hit, t, q, flags=None):
         self.hit = hit