From 8eb75f80351751b25b9c65c3eae81513b7a4e9dd Mon Sep 17 00:00:00 2001
From: Jerome Kelleher <jk@well.ox.ac.uk>
Date: Mon, 21 Oct 2024 22:35:10 +0100
Subject: [PATCH] Fix time-zero logic

---
 sc2ts/info.py | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/sc2ts/info.py b/sc2ts/info.py
index 257ed7c..d741f64 100644
--- a/sc2ts/info.py
+++ b/sc2ts/info.py
@@ -492,10 +492,8 @@ def _preprocess_nodes(self, show_progress):
         self.nodes_metadata = {}
         self.nodes_sample_group = collections.defaultdict(list)
         samples = ts.samples()
-        last_sample = ts.node(samples[-1])
 
-        self.nodes_date[last_sample.id] = last_sample.metadata["date"]
-        self.time_zero_as_date = self.nodes_date[last_sample.id]
+        self.time_zero_as_date = np.array([self.date], dtype="datetime64[D]")[0]
         self.earliest_pango_lineage = {}
         self.pango_lineage_samples = collections.defaultdict(list)