From 1784757f13dc035fcbc9ded001a315c27c01c086 Mon Sep 17 00:00:00 2001
From: Justus Winter <teythoon@avior.uberspace.de>
Date: Mon, 4 May 2020 13:38:55 +0200
Subject: [PATCH] Remove species that no longer have any organisms.

Fixes #19.
---
 src/population.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/population.rs b/src/population.rs
index c18bd2b..14f79f3 100644
--- a/src/population.rs
+++ b/src/population.rs
@@ -172,6 +172,9 @@ impl Population {
                 self.species.push(new_specie.unwrap());
             }
         }
+
+        // Remove species that no longer have any organisms.
+        self.species.retain(|s| ! s.organisms.is_empty());
     }
 
     fn create_organisms(&mut self, population_size: usize) {