Tests

databricks/koalas/plot/plotly.py

@@ -62,19 +62,9 @@ def plot_histogram(data, **kwargs):
     import plotly.graph_objs as go
     from databricks import koalas as ks
 
-    assert "bins" in kwargs
-    bins = kwargs["bins"]
-    data, bins = HistogramPlotBase.prepare_hist_data(data, bins)
-
-    is_single_column = False
-    if isinstance(data, ks.Series):
-        is_single_column = True
-        kdf = data.to_frame()
-    elif isinstance(data, ks.DataFrame):
-        kdf = data
-    else:
-        raise RuntimeError("Unexpected type: [%s]" % type(data))
-
+    bins = kwargs.get("bins", 10)
+    is_single_column = isinstance(data, ks.Series)
+    kdf, bins = HistogramPlotBase.prepare_hist_data(data, bins)
     output_series = HistogramPlotBase.compute_hist(kdf, bins)
     bins = 0.5 * (bins[:-1] + bins[1:])
     if is_single_column:

databricks/koalas/tests/plot/test_frame_plot.py

@@ -81,7 +81,7 @@ def test_compute_hist_single_column(self):
         expected_histogram = np.array([5, 4, 1, 0, 0, 0, 0, 0, 0, 1])
         histogram = HistogramPlotBase.compute_hist(kdf[["a"]], bins)[0]
         self.assert_eq(pd.Series(expected_bins), pd.Series(bins))
-        self.assert_eq(pd.Series(expected_histogram, name="__a_bucket"), histogram, almost=True)
+        self.assert_eq(pd.Series(expected_histogram, name="a"), histogram, almost=True)
 
     def test_compute_hist_multi_columns(self):
         expected_bins = np.linspace(1, 50, 11)
@@ -100,7 +100,7 @@ def test_compute_hist_multi_columns(self):
             np.array([4, 1, 0, 0, 1, 3, 0, 0, 0, 2]),
         ]
         histograms = HistogramPlotBase.compute_hist(kdf, bins)
-        expected_names = ["__a_bucket", "__b_bucket"]
+        expected_names = ["a", "b"]
 
         for histogram, expected_histogram, expected_name in zip(
             histograms, expected_histograms, expected_names

databricks/koalas/tests/plot/test_frame_plot_plotly.py

@@ -15,14 +15,18 @@
 #
 import unittest
 from distutils.version import LooseVersion
+import pprint
 
 import pandas as pd
 import numpy as np
 from plotly import express
+from plotly.subplots import make_subplots
+import plotly.graph_objs as go
 
 from databricks import koalas as ks
 from databricks.koalas.config import set_option, reset_option
 from databricks.koalas.testing.utils import ReusedSQLTestCase, TestUtils
+from databricks.koalas.utils import name_like_string
 
 
 @unittest.skipIf(
@@ -174,3 +178,35 @@ def check_pie_plot(kdf):
         #     index=pd.MultiIndex.from_tuples([("x", "y")] * 11),
         # )
         # check_pie_plot(kdf1)
+
+    def test_hist_plot(self):
+        def check_hist_plot(kdf):
+            bins = np.array([1.0, 5.9, 10.8, 15.7, 20.6, 25.5, 30.4, 35.3, 40.2, 45.1, 50.0])
+            bins = 0.5 * (bins[:-1] + bins[1:])
+            data = [
+                np.array([5.0, 4.0, 1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 1.0,]),
+                np.array([4.0, 3.0, 1.0, 0.0, 0.0, 0.0, 1.0, 0.0, 1.0, 1.0,]),
+            ]
+
+            fig = make_subplots(rows=1, cols=len(data))
+            fig.add_trace(
+                go.Bar(x=bins, y=data[0], name=name_like_string(kdf.columns[0]),), row=1, col=1
+            )
+            fig.add_trace(
+                go.Bar(x=bins, y=data[1], name=name_like_string(kdf.columns[1]),), row=1, col=2
+            )
+            fig["layout"]["xaxis"]["title"] = name_like_string(kdf.columns[0])
+            fig["layout"]["yaxis"]["title"] = "count"
+            fig["layout"]["xaxis2"]["title"] = name_like_string(kdf.columns[1])
+            fig["layout"]["yaxis2"]["title"] = "count"
+
+            self.assertEqual(
+                pprint.pformat(kdf.plot(kind="hist").to_dict()), pprint.pformat(fig.to_dict())
+            )
+
+        kdf1 = self.kdf1
+        check_hist_plot(kdf1)
+
+        columns = pd.MultiIndex.from_tuples([("x", "y"), ("y", "z")])
+        kdf1.columns = columns
+        check_hist_plot(kdf1)

databricks/koalas/tests/plot/test_series_plot_plotly.py

@@ -15,13 +15,16 @@
 #
 import unittest
 from distutils.version import LooseVersion
+import pprint
 
 import pandas as pd
+import numpy as np
 from plotly import express
 
 from databricks import koalas as ks
 from databricks.koalas.config import set_option, reset_option
 from databricks.koalas.testing.utils import ReusedSQLTestCase, TestUtils
+from databricks.koalas.utils import name_like_string
 
 
 @unittest.skipIf(
@@ -128,3 +131,25 @@ def test_pie_plot(self):
         # self.assertEqual(
         #     kdf["a"].plot(kind="pie"), express.pie(pdf, values=pdf.columns[0], names=pdf.index),
         # )
+
+    def test_hist_plot(self):
+        def check_hist_plot(kser):
+            bins = np.array([1.0, 5.9, 10.8, 15.7, 20.6, 25.5, 30.4, 35.3, 40.2, 45.1, 50.0])
+            bins = 0.5 * (bins[:-1] + bins[1:])
+            data = pd.Series(
+                np.array([5.0, 4.0, 1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 1.0,]), name=kser.name
+            )
+            fig = express.bar(
+                x=bins, y=data, labels={"x": name_like_string(data.name), "y": "count"}
+            )
+
+            self.assertEqual(
+                pprint.pformat(kser.plot(kind="hist").to_dict()), pprint.pformat(fig.to_dict())
+            )
+
+        kdf1 = self.kdf1
+        check_hist_plot(kdf1["a"])
+
+        columns = pd.MultiIndex.from_tuples([("x", "y")])
+        kdf1.columns = columns
+        check_hist_plot(kdf1[("x", "y")])