From b525b026a250ae416a0d8299f9d8dc65720f2609 Mon Sep 17 00:00:00 2001
From: Peter Chang <40067028+JyChang012@users.noreply.github.com>
Date: Sat, 16 Jul 2022 22:26:53 -0400
Subject: [PATCH] Fix bug in flattening list of lists. (#32)

---
 src/rsdiv/evaluation/diversity_metrics.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/rsdiv/evaluation/diversity_metrics.py b/src/rsdiv/evaluation/diversity_metrics.py
index 68dc1cb..91f2440 100644
--- a/src/rsdiv/evaluation/diversity_metrics.py
+++ b/src/rsdiv/evaluation/diversity_metrics.py
@@ -15,7 +15,8 @@ class DiversityMetrics:
     def _get_histogram(
         items: Union[Iterable[Hashable], Iterable[Sequence[Hashable]]],
     ) -> np.ndarray:
-        if isinstance(next(iter(items)), Sequence):
+        first_element = next(iter(items))
+        if isinstance(first_element, Sequence) and not isinstance(first_element, str):
             items = chain(*items)
         flatten_items = list(items)
         return np.asarray(pd.Series(flatten_items).value_counts())
@@ -80,7 +81,8 @@ def get_lorenz_curve(
     def get_distribution(
         cls, items: Union[Iterable[Hashable], Iterable[Sequence[Hashable]]]
     ) -> pd.DataFrame:
-        if isinstance(next(iter(items)), Sequence):
+        first_element = next(iter(items))
+        if isinstance(first_element, Sequence) and not isinstance(first_element, str):
             items = chain(*items)
         counter: pd.DataFrame = pd.DataFrame(Counter(items).most_common())
         counter.columns = pd.Index(["category", "percentage"])