From 7ad311bbb737036b1553d7b80fda7e276d4b87f6 Mon Sep 17 00:00:00 2001
From: heath <alexander.t.heath@gmail.com>
Date: Tue, 9 Apr 2019 10:37:58 -0400
Subject: [PATCH] Implemented dropna bug fix for plt.hist

---
 seaborn/axisgrid.py            | 9 +++++++++
 seaborn/tests/test_axisgrid.py | 7 +++++++
 2 files changed, 16 insertions(+)

diff --git a/seaborn/axisgrid.py b/seaborn/axisgrid.py
index 6caf66b38a..8b518e2833 100644
--- a/seaborn/axisgrid.py
+++ b/seaborn/axisgrid.py
@@ -1273,6 +1273,9 @@ def __init__(self, data, hue=None, hue_order=None, palette=None,
         self.axes = axes
         self.data = data
 
+        # Save dropna variable to dictate filtering steps when plotting
+        self._dropna = dropna
+
         # Save what we are going to do with the diagonal
         self.diag_sharey = diag_sharey
         self.diag_axes = None
@@ -1391,6 +1394,12 @@ def map_diag(self, func, **kwargs):
                 except KeyError:
                     data_k = np.array([])
 
+                if self._dropna:
+                    data_k = utils.remove_na(data_k)
+                else:
+                    if np.sum(np.isnan(data_k), axis=0).sum() > 0:
+                        raise ValueError("Cannot plot histograms for data containing NAs. Please filter out NAs or pass `dropna=True`.")
+
                 if fixed_color is None:
                     color = self.palette[k]
                 else:
diff --git a/seaborn/tests/test_axisgrid.py b/seaborn/tests/test_axisgrid.py
index c7e182424b..d4736406ef 100644
--- a/seaborn/tests/test_axisgrid.py
+++ b/seaborn/tests/test_axisgrid.py
@@ -924,6 +924,13 @@ def test_map_diag(self):
             for ptch in ax.patches:
                 nt.assert_equal(ptch.fill, False)
 
+        na_df = self.df.copy()
+        for i, var in enumerate(self.df.columns.values):
+            na_df.iloc[np.random.randint(len(na_df)), i] = np.nan
+
+        g5 = ag.PairGrid(na_df, dropna=True)
+        g5.map_diag(plt.hist)
+
     def test_map_diag_color(self):
 
         color = "red"