From 6ffdd2611d53f5a6811e445d5b07182af163ea23 Mon Sep 17 00:00:00 2001
From: Chris Leaman <ckleaman@gmail.com>
Date: Mon, 4 Mar 2019 15:41:19 +1100
Subject: [PATCH] Allow crossing to return empty list if all values are masked

---
 src/utils.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/utils.py b/src/utils.py
index f5b8067..772de7b 100644
--- a/src/utils.py
+++ b/src/utils.py
@@ -23,6 +23,10 @@ def crossings(profile_x, profile_z, constant_z):
     profile_z = np.array(profile_z)[valid]
     profile_x = np.array(profile_x)[valid]
 
+    # Return empty list if mask removes all values
+    if profile_x.size == 0:
+        return []
+
     # Normalize the 'signal' to zero.
     # Use np.subtract rather than a list comprehension for performance reasons
     z = np.subtract(profile_z, constant_z)