From cbb44a2352549f6a28e125c841014bf2f4b441dd Mon Sep 17 00:00:00 2001
From: Janosh Riebesell <janosh.riebesell@gmail.com>
Date: Fri, 17 Nov 2023 12:26:53 -0800
Subject: [PATCH] fix PhononDosPlotter.get_plot only ax.set_ylim if relevant_y
 is non-empty

---
 pymatgen/core/units.py     | 24 ++++++++++++------------
 pymatgen/phonon/plotter.py |  3 ++-
 2 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/pymatgen/core/units.py b/pymatgen/core/units.py
index 94dc97fab8f..6cb3492e71c 100644
--- a/pymatgen/core/units.py
+++ b/pymatgen/core/units.py
@@ -207,10 +207,10 @@ def __pow__(self, i):
     def __iter__(self):
         return iter(self._unit)
 
-    def __getitem__(self, i):
+    def __getitem__(self, i) -> int:
         return self._unit[i]
 
-    def __len__(self):
+    def __len__(self) -> int:
         return len(self._unit)
 
     def __repr__(self):
@@ -254,16 +254,16 @@ def get_conversion_factor(self, new_unit):
         Args:
             new_unit: The new unit.
         """
-        uo_base, ofactor = self.as_base_units
-        un_base, nfactor = Unit(new_unit).as_base_units
-        units_new = sorted(un_base.items(), key=lambda d: _UNAME2UTYPE[d[0]])
-        units_old = sorted(uo_base.items(), key=lambda d: _UNAME2UTYPE[d[0]])
-        factor = ofactor / nfactor
-        for uo, un in zip(units_old, units_new):
-            if uo[1] != un[1]:
-                raise UnitError(f"Units {uo} and {un} are not compatible!")
-            c = ALL_UNITS[_UNAME2UTYPE[uo[0]]]
-            factor *= (c[uo[0]] / c[un[0]]) ** uo[1]
+        old_base, old_factor = self.as_base_units
+        new_base, new_factor = Unit(new_unit).as_base_units
+        units_new = sorted(new_base.items(), key=lambda d: _UNAME2UTYPE[d[0]])
+        units_old = sorted(old_base.items(), key=lambda d: _UNAME2UTYPE[d[0]])
+        factor = old_factor / new_factor
+        for old, new in zip(units_old, units_new):
+            if old[1] != new[1]:
+                raise UnitError(f"Units {old} and {new} are not compatible!")
+            c = ALL_UNITS[_UNAME2UTYPE[old[0]]]
+            factor *= (c[old[0]] / c[new[0]]) ** old[1]
         return factor
 
 
diff --git a/pymatgen/phonon/plotter.py b/pymatgen/phonon/plotter.py
index 9daa2d617b8..b032632cfde 100644
--- a/pymatgen/phonon/plotter.py
+++ b/pymatgen/phonon/plotter.py
@@ -191,7 +191,8 @@ def get_plot(
         else:
             _xlim = ax.set_xlim()
             relevant_y = [p[1] for p in all_pts if _xlim[0] < p[0] < _xlim[1]]
-            ax.set_ylim((min(relevant_y), max(relevant_y)))
+            if len(relevant_y) > 0:
+                ax.set_ylim((min(relevant_y), max(relevant_y)))
 
         ylim = ax.set_ylim()
         ax.plot([0, 0], ylim, "k--", linewidth=2)