code sample for pandas-dev#36953

Author: simonjayhawkins

bisect/36951.py

@@ -0,0 +1,32 @@
+import pandas as pd
+
+print(pd.__version__)
+
+df = pd.DataFrame(
+    {"col": range(10)}, index=pd.date_range("2012-01-01", periods=10, freq="20min")
+)
+
+res = df.resample("H").apply(lambda group: len(group["col"].unique()))
+print(res)
+
+index = pd.DatetimeIndex(
+    [
+        "2012-01-01 00:00:00",
+        "2012-01-01 01:00:00",
+        "2012-01-01 02:00:00",
+        "2012-01-01 03:00:00",
+    ],
+    dtype="datetime64[ns]",
+    freq="H",
+)
+
+expected = pd.Series([3, 3, 3, 1], index=index)
+
+import pandas.testing as tm
+
+tm.assert_series_equal(res, expected)
+
+res2 = df.resample("H").apply(lambda group: len(group.col.unique()))
+print(res2)
+
+tm.assert_series_equal(res2, expected)