From bbe0d26f810647863c61ac5ea03cc2f055861b58 Mon Sep 17 00:00:00 2001
From: Lily Wang <lily@minium.com.au>
Date: Thu, 7 Nov 2019 01:59:44 +1100
Subject: [PATCH] guess zinc properly

---
 package/CHANGELOG                                   | 1 +
 package/MDAnalysis/topology/guessers.py             | 7 ++++++-
 testsuite/MDAnalysisTests/topology/test_guessers.py | 4 +++-
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/package/CHANGELOG b/package/CHANGELOG
index 12b67be1c2a..3a732996c23 100644
--- a/package/CHANGELOG
+++ b/package/CHANGELOG
@@ -24,6 +24,7 @@ Fixes
   * Chainreader and continuous option work correctly when readers work for more 
     than one format (Issue #2353)
   * PDBQTParser now gives icode TopologyAttrs (Issue #2361)
+  * Guess atom element with uppercase name
 
 Enhancements
   * Uniforms exception handling between Python 2.7 and Python 3: raised exceptions
diff --git a/package/MDAnalysis/topology/guessers.py b/package/MDAnalysis/topology/guessers.py
index cd61f61a0c5..495b8406273 100644
--- a/package/MDAnalysis/topology/guessers.py
+++ b/package/MDAnalysis/topology/guessers.py
@@ -134,11 +134,16 @@ def guess_atom_element(atomname):
     if atomname == '':
         return ''
     try:
-        return tables.atomelements[atomname]
+        return tables.atomelements[atomname.upper()]
     except KeyError:
         # strip symbols and numbers
         no_symbols = re.sub(SYMBOLS, '', atomname)
         name = re.sub(NUMBERS, '', no_symbols).upper()
+
+        # just in case
+        if name in tables.atomelements:
+            return tables.atomelements[name]
+
         while name:
             if name in tables.elements:
                 return name
diff --git a/testsuite/MDAnalysisTests/topology/test_guessers.py b/testsuite/MDAnalysisTests/topology/test_guessers.py
index cf7c69e8c1e..8b5e4fe08bc 100644
--- a/testsuite/MDAnalysisTests/topology/test_guessers.py
+++ b/testsuite/MDAnalysisTests/topology/test_guessers.py
@@ -89,7 +89,9 @@ def test_guess_atom_element_1H(self):
         ('3hg2', 'H'),
         ('OH-', 'O'),
         ('HO', 'H'),
-        ('he', 'H')
+        ('he', 'H'), 
+        ('zn', 'ZN'),
+        ('Ca2+', 'CA'),
     ))
     def test_guess_element_from_name(self, name, element):
         assert guessers.guess_atom_element(name) == element