From b7d0b067fbbc6a953f11f29bf2d8f5f02e0ae262 Mon Sep 17 00:00:00 2001
From: Cade Duckworth <104414304+cadeduckworth@users.noreply.github.com>
Date: Mon, 27 Mar 2023 12:22:59 -0500
Subject: [PATCH] Periodic Angle Padding (#242)

* fix #241
* add .copy(deep=True) method for dataframe augmentation to avoid pandas potentially loosing changes
  to a df due to working on a copy after indexing
* update CHANGES
* note: Tests pass as before so no functional code changes but more robust code
---
 CHANGES                      | 2 ++
 mdpow/workflows/dihedrals.py | 6 +++---
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/CHANGES b/CHANGES
index dee0e09f..613ff8c5 100644
--- a/CHANGES
+++ b/CHANGES
@@ -30,6 +30,8 @@ Enhancements
 
 Fixes
 
+* for mdpow.workflows.dihedrals.periodic_angle() implement .copy(deep=True)
+  to explicitly make a copy DataFrame of the data for angle padding (#242)
 * fix rcoulomb in CHARMM energy minimization MDP template file (PR #210)
 * fix ensemble.EnsembleAnalysis.check_groups_from_common_ensemble (#212)
 
diff --git a/mdpow/workflows/dihedrals.py b/mdpow/workflows/dihedrals.py
index a9ae5036..63b4d6a1 100644
--- a/mdpow/workflows/dihedrals.py
+++ b/mdpow/workflows/dihedrals.py
@@ -418,11 +418,11 @@ def periodic_angle(df, padding=45):
 
     '''
 
-    df1 = df[df.dihedral > 180 - padding]
+    df1 = df[df.dihedral > 180 - padding].copy(deep=True)
     df1.dihedral -= 360
-    df2 = df[df.dihedral < -180 + padding]
+    df2 = df[df.dihedral < -180 + padding].copy(deep=True)
     df2.dihedral += 360
-    df_aug = pd.concat([df1, df, df2]).reset_index()
+    df_aug = pd.concat([df1, df, df2]).reset_index(drop=True)
 
     return df_aug