Fix Prophet.resample_time_stamps bug (#112)

* add unit test for Prophet.resample_time_stamps

test failing at this commit because of the bug

* fix bug in Prophet.resample_time_stamps

merlion/models/forecast/prophet.py

@@ -209,7 +209,7 @@ def _train(self, train_data: pd.DataFrame, train_config=None):
 
     def resample_time_stamps(self, time_stamps: Union[int, List[int]], time_series_prev: TimeSeries = None):
         if isinstance(time_stamps, (int, float)):
-            times = pd.date_range(start=self.last_train_time, freq=self.timedelta, periods=int(time_stamps))[1:]
+            times = pd.date_range(start=self.last_train_time, freq=self.timedelta, periods=int(time_stamps + 1))[1:]
             time_stamps = to_timestamp(times)
         return time_stamps
 

tests/forecast/test_prophet.py

@@ -0,0 +1,23 @@
+import unittest
+
+import pandas as pd
+import numpy as np
+
+from merlion.models.forecast.prophet import Prophet, ProphetConfig
+from merlion.utils.resample import to_timestamp
+
+
+class TestProphet(unittest.TestCase):
+    def test_resample_time_stamps(self):
+        # arrange
+        config = ProphetConfig()
+        prophet = Prophet(config)
+        prophet.last_train_time = pd._libs.tslibs.timestamps.Timestamp(year=2022, month=1, day=1)
+        prophet.timedelta = pd._libs.tslibs.timedeltas.Timedelta(days=1)
+        target = np.array([to_timestamp(pd._libs.tslibs.timestamps.Timestamp(year=2022, month=1, day=2))])
+
+        # act
+        output = prophet.resample_time_stamps(time_stamps=1)
+
+        # assert
+        assert output == target