Grouper using frequency has inconsistent behavior inside and outside a list

[prcastro]

Code Sample

>>> df.groupby(pd.Grouper(freq='H')).agg({'value': 'mean'})
            timestamp       delta_t
2016-06-07 00:00:00  2.729111e+11
2016-06-07 01:00:00           NaN
2016-06-07 02:00:00           NaN
2016-06-07 03:00:00           NaN
2016-06-07 04:00:00           NaN
...

>>> df.groupby([pd.Grouper(freq='H')]).agg({'value': 'mean'})
   timestamp       delta_t
2016-06-07  2.729111e+11
2016-07-07  2.509444e+11
2016-07-13  2.775778e+11
2016-07-15  2.490556e+11
2016-07-16  2.676190e+11

Problem description

This is an inconsistent behavior, and there is no mention to this on groupby or Grouper documentation.

Expected Output

>>> df.groupby([pd.Grouper(freq='H')]).agg({'value': 'mean'})
   timestamp       delta_t
2016-06-07 00:00:00  2.729111e+11
2016-06-07 01:00:00           NaN
2016-06-07 02:00:00           NaN
2016-06-07 03:00:00           NaN
2016-06-07 04:00:00           NaN

Output of pd.show_versions()

pandas: 0.20.2 pytest: 3.1.1 pip: 9.0.1 setuptools: 27.2.0 Cython: 0.25.2 numpy: 1.12.1 scipy: 0.19.0 xarray: 0.9.6 IPython: 6.1.0 sphinx: 1.5.6 patsy: 0.4.1 dateutil: 2.6.0 pytz: 2017.2 blosc: None bottleneck: 1.2.1 tables: 3.3.0 numexpr: 2.6.2 feather: None matplotlib: 2.0.2 openpyxl: 2.4.7 xlrd: 1.0.0 xlwt: 1.2.0 xlsxwriter: 0.9.6 lxml: 3.8.0 bs4: 4.6.0 html5lib: 0.999 sqlalchemy: 1.1.10 pymysql: None psycopg2: None jinja2: 2.9.6 s3fs: None pandas_gbq: None pandas_datareader: None

[jreback]

You would have to show a complete example. How is it different from this. (which is on master).

In [8]: df = pd.DataFrame({'A': range(10), 'B': pd.date_range('20170101', periods=10, freq='30min')})

In [9]: df
Out[9]: 
   A                   B
0  0 2017-01-01 00:00:00
1  1 2017-01-01 00:30:00
2  2 2017-01-01 01:00:00
3  3 2017-01-01 01:30:00
4  4 2017-01-01 02:00:00
5  5 2017-01-01 02:30:00
6  6 2017-01-01 03:00:00
7  7 2017-01-01 03:30:00
8  8 2017-01-01 04:00:00
9  9 2017-01-01 04:30:00

In [10]: df.groupby(pd.Grouper(key='B', freq='H')).agg({'A': 'mean'})
Out[10]: 
                       A
B                       
2017-01-01 00:00:00  0.5
2017-01-01 01:00:00  2.5
2017-01-01 02:00:00  4.5
2017-01-01 03:00:00  6.5
2017-01-01 04:00:00  8.5

In [11]: df.groupby([pd.Grouper(key='B', freq='H')]).agg({'A': 'mean'})
Out[11]: 
                       A
B                       
2017-01-01 00:00:00  0.5
2017-01-01 01:00:00  2.5
2017-01-01 02:00:00  4.5
2017-01-01 03:00:00  6.5
2017-01-01 04:00:00  8.5

[prcastro]

This data reproduces the bug, when using timestamp as the index of the dataframe (sorry to give you the data in the body of a comment, but I'm behind a coorporate proxy, and don't have access to upload platforms like pastebin):

timestamp,value
2016-06-07 00:00:39.000000,75000000000
2016-06-07 00:00:39.000000,149000000000
2016-06-07 00:00:39.000000,223000000000
2016-06-07 00:00:39.000000,297000000000
2016-06-07 00:00:39.000000,372000000000
2016-06-07 00:00:39.000000,446000000000
2016-06-07 00:00:39.000000,521000000000
2016-06-07 00:00:39.000000,596000000000
2016-06-07 00:00:39.000000,670000000000
2016-06-07 00:01:54.000000,74000000000
2016-06-07 00:01:54.000000,148000000000
2016-06-07 00:01:54.000000,222000000000
2016-06-07 00:01:54.000000,297000000000
2016-06-07 00:01:54.000000,371000000000
2016-06-07 00:01:54.000000,446000000000
2016-06-07 00:01:54.000000,521000000000
2016-06-07 00:01:54.000000,595000000000
2016-06-07 00:03:08.000000,74000000000
2016-06-07 00:03:08.000000,148000000000
2016-06-07 00:03:08.000000,223000000000
2016-06-07 00:03:08.000000,297000000000
2016-06-07 00:03:08.000000,372000000000
2016-06-07 00:03:08.000000,447000000000
2016-06-07 00:03:08.000000,521000000000
2016-06-07 00:04:22.000000,74000000000
2016-06-07 00:04:22.000000,149000000000
2016-06-07 00:04:22.000000,223000000000
2016-06-07 00:04:22.000000,298000000000
2016-06-07 00:04:22.000000,373000000000
2016-06-07 00:04:22.000000,447000000000
2016-06-07 00:05:36.000000,75000000000
2016-06-07 00:05:36.000000,149000000000
2016-06-07 00:05:36.000000,224000000000
2016-06-07 00:05:36.000000,299000000000
2016-06-07 00:05:36.000000,373000000000
2016-06-07 00:06:51.000000,74000000000
2016-06-07 00:06:51.000000,149000000000
2016-06-07 00:06:51.000000,224000000000
2016-06-07 00:06:51.000000,298000000000
2016-06-07 00:08:05.000000,75000000000
2016-06-07 00:08:05.000000,150000000000
2016-06-07 00:08:05.000000,224000000000
2016-06-07 00:09:20.000000,75000000000
2016-06-07 00:09:20.000000,149000000000
2016-06-07 00:10:35.000000,74000000000
2016-07-13 00:00:56.000000,76000000000
2016-07-13 00:00:56.000000,152000000000
2016-07-13 00:00:56.000000,228000000000
2016-07-13 00:00:56.000000,304000000000
2016-07-13 00:00:56.000000,379000000000
2016-07-13 00:00:56.000000,454000000000
2016-07-13 00:00:56.000000,530000000000
2016-07-13 00:00:56.000000,606000000000
2016-07-13 00:00:56.000000,682000000000
2016-07-13 00:02:12.000000,76000000000
2016-07-13 00:02:12.000000,152000000000
2016-07-13 00:02:12.000000,228000000000
2016-07-13 00:02:12.000000,303000000000
2016-07-13 00:02:12.000000,378000000000
2016-07-13 00:02:12.000000,454000000000
2016-07-13 00:02:12.000000,530000000000
2016-07-13 00:02:12.000000,606000000000
2016-07-13 00:03:28.000000,76000000000
2016-07-13 00:03:28.000000,152000000000
2016-07-13 00:03:28.000000,227000000000
2016-07-13 00:03:28.000000,302000000000
2016-07-13 00:03:28.000000,378000000000
2016-07-13 00:03:28.000000,454000000000
2016-07-13 00:03:28.000000,530000000000
2016-07-13 00:04:44.000000,76000000000
2016-07-13 00:04:44.000000,151000000000
2016-07-13 00:04:44.000000,226000000000
2016-07-13 00:04:44.000000,302000000000
2016-07-13 00:04:44.000000,378000000000
2016-07-13 00:04:44.000000,454000000000
2016-07-13 00:06:00.000000,75000000000
2016-07-13 00:06:00.000000,150000000000
2016-07-13 00:06:00.000000,226000000000
2016-07-13 00:06:00.000000,302000000000
2016-07-13 00:06:00.000000,378000000000
2016-07-13 00:07:15.000000,75000000000
2016-07-13 00:07:15.000000,151000000000
2016-07-13 00:07:15.000000,227000000000
2016-07-13 00:07:15.000000,303000000000
2016-07-13 00:08:30.000000,76000000000
2016-07-13 00:08:30.000000,152000000000
2016-07-13 00:08:30.000000,228000000000
2016-07-13 00:09:46.000000,76000000000
2016-07-13 00:09:46.000000,152000000000
2016-07-13 00:11:02.000000,76000000000
2016-07-15 00:02:21.000000,75000000000
2016-07-15 00:02:21.000000,150000000000
2016-07-15 00:02:21.000000,225000000000
2016-07-15 00:02:21.000000,300000000000
2016-07-15 00:02:21.000000,374000000000
2016-07-15 00:02:21.000000,449000000000
2016-07-15 00:02:21.000000,523000000000
2016-07-15 00:02:21.000000,598000000000
2016-07-15 00:03:36.000000,75000000000
2016-07-15 00:03:36.000000,150000000000
2016-07-15 00:03:36.000000,225000000000
2016-07-15 00:03:36.000000,299000000000
2016-07-15 00:03:36.000000,374000000000
2016-07-15 00:03:36.000000,448000000000
2016-07-15 00:03:36.000000,523000000000
2016-07-15 00:04:51.000000,75000000000
2016-07-15 00:04:51.000000,150000000000
2016-07-15 00:04:51.000000,224000000000
2016-07-15 00:04:51.000000,299000000000
2016-07-15 00:04:51.000000,373000000000
2016-07-15 00:04:51.000000,448000000000
2016-07-15 00:06:06.000000,75000000000
2016-07-15 00:06:06.000000,149000000000
2016-07-15 00:06:06.000000,224000000000
2016-07-15 00:06:06.000000,298000000000
2016-07-15 00:06:06.000000,373000000000
2016-07-15 00:07:21.000000,74000000000
2016-07-15 00:07:21.000000,149000000000
2016-07-15 00:07:21.000000,223000000000
2016-07-15 00:07:21.000000,298000000000
2016-07-15 00:08:35.000000,75000000000
2016-07-15 00:08:35.000000,149000000000
2016-07-15 00:08:35.000000,224000000000
2016-07-15 00:09:50.000000,74000000000
2016-07-15 00:09:50.000000,149000000000
2016-07-15 00:11:04.000000,75000000000
2016-10-07 00:01:07.000000,76000000000
2016-10-07 00:01:07.000000,152000000000
2016-10-07 00:01:07.000000,227000000000
2016-10-07 00:01:07.000000,303000000000
2016-10-07 00:01:07.000000,378000000000
2016-10-07 00:01:07.000000,453000000000
2016-10-07 00:01:07.000000,528000000000
2016-10-07 00:01:07.000000,603000000000
2016-10-07 00:01:07.000000,677000000000
2016-10-07 00:01:07.000000,751000000000
2016-10-07 00:01:07.000000,825000000000
2016-10-07 00:02:23.000000,76000000000
2016-10-07 00:02:23.000000,151000000000
2016-10-07 00:02:23.000000,227000000000
2016-10-07 00:02:23.000000,302000000000
2016-10-07 00:02:23.000000,377000000000
2016-10-07 00:02:23.000000,452000000000
2016-10-07 00:02:23.000000,527000000000
2016-10-07 00:02:23.000000,601000000000
2016-10-07 00:02:23.000000,675000000000
2016-10-07 00:02:23.000000,749000000000
2016-10-07 00:03:39.000000,75000000000
2016-10-07 00:03:39.000000,151000000000
2016-10-07 00:03:39.000000,226000000000
2016-10-07 00:03:39.000000,301000000000
2016-10-07 00:03:39.000000,376000000000
2016-10-07 00:03:39.000000,451000000000
2016-10-07 00:03:39.000000,525000000000
2016-10-07 00:03:39.000000,599000000000
2016-10-07 00:03:39.000000,673000000000
2016-10-07 00:04:54.000000,76000000000
2016-10-07 00:04:54.000000,151000000000
2016-10-07 00:04:54.000000,226000000000
2016-10-07 00:04:54.000000,301000000000
2016-10-07 00:04:54.000000,376000000000
2016-10-07 00:04:54.000000,450000000000
2016-10-07 00:04:54.000000,524000000000
2016-10-07 00:04:54.000000,598000000000
2016-10-07 00:06:10.000000,75000000000
2016-10-07 00:06:10.000000,150000000000
2016-10-07 00:06:10.000000,225000000000
2016-10-07 00:06:10.000000,300000000000
2016-10-07 00:06:10.000000,374000000000
2016-10-07 00:06:10.000000,448000000000
2016-10-07 00:06:10.000000,522000000000
2016-10-07 00:07:25.000000,75000000000
2016-10-07 00:07:25.000000,150000000000
2016-10-07 00:07:25.000000,225000000000
2016-10-07 00:07:25.000000,299000000000
2016-10-07 00:07:25.000000,373000000000
2016-10-07 00:07:25.000000,447000000000
2016-10-07 00:08:40.000000,75000000000
2016-10-07 00:08:40.000000,150000000000
2016-10-07 00:08:40.000000,224000000000
2016-10-07 00:08:40.000000,298000000000
2016-10-07 00:08:40.000000,372000000000
2016-10-07 00:09:55.000000,75000000000
2016-10-07 00:09:55.000000,149000000000
2016-10-07 00:09:55.000000,223000000000
2016-10-07 00:09:55.000000,297000000000
2016-10-07 00:11:10.000000,74000000000
2016-10-07 00:11:10.000000,148000000000
2016-10-07 00:11:10.000000,222000000000
2016-10-07 00:12:24.000000,74000000000
2016-10-07 00:12:24.000000,148000000000
2016-10-07 00:13:38.000000,74000000000
2016-07-07 00:01:43.000000,76000000000
2016-07-07 00:01:43.000000,151000000000
2016-07-07 00:01:43.000000,226000000000
2016-07-07 00:01:43.000000,302000000000
2016-07-07 00:01:43.000000,378000000000
2016-07-07 00:01:43.000000,453000000000
2016-07-07 00:01:43.000000,527000000000
2016-07-07 00:01:43.000000,602000000000
2016-07-07 00:02:59.000000,75000000000
2016-07-07 00:02:59.000000,150000000000
2016-07-07 00:02:59.000000,226000000000
2016-07-07 00:02:59.000000,302000000000
2016-07-07 00:02:59.000000,377000000000
2016-07-07 00:02:59.000000,451000000000
2016-07-07 00:02:59.000000,526000000000
2016-07-07 00:04:14.000000,75000000000
2016-07-07 00:04:14.000000,151000000000
2016-07-07 00:04:14.000000,227000000000
2016-07-07 00:04:14.000000,302000000000
2016-07-07 00:04:14.000000,376000000000
2016-07-07 00:04:14.000000,451000000000
2016-07-07 00:05:29.000000,76000000000
2016-07-07 00:05:29.000000,152000000000
2016-07-07 00:05:29.000000,227000000000
2016-07-07 00:05:29.000000,301000000000
2016-07-07 00:05:29.000000,376000000000
2016-07-07 00:06:45.000000,76000000000
2016-07-07 00:06:45.000000,151000000000
2016-07-07 00:06:45.000000,225000000000
2016-07-07 00:06:45.000000,300000000000
2016-07-07 00:08:01.000000,75000000000
2016-07-07 00:08:01.000000,149000000000
2016-07-07 00:08:01.000000,224000000000
2016-07-07 00:09:16.000000,74000000000
2016-07-07 00:09:16.000000,149000000000
2016-07-07 00:10:30.000000,75000000000
2016-07-23 00:03:12.400000,222600000000
2016-07-23 00:03:12.400000,297600000000
2016-07-23 00:03:12.400000,371600000000
2016-07-23 00:03:12.400000,482100000000
2016-07-23 00:06:55.000000,75000000000
2016-07-23 00:06:55.000000,149000000000
2016-07-23 00:06:55.000000,259500000000
2016-07-23 00:08:10.000000,74000000000
2016-07-23 00:08:10.000000,184500000000
2016-07-23 00:09:24.000000,110500000000
2016-07-26 00:01:55.000000,113000000000
2016-07-26 00:01:55.000000,226000000000
2016-07-26 00:01:55.000000,301000000000
2016-07-26 00:01:55.000000,414000000000
2016-07-26 00:01:55.000000,564500000000
2016-07-26 00:03:48.000000,113000000000
2016-07-26 00:03:48.000000,188000000000
2016-07-26 00:03:48.000000,301000000000
2016-07-26 00:03:48.000000,451500000000
2016-07-26 00:05:41.000000,75000000000
2016-07-26 00:05:41.000000,188000000000
2016-07-26 00:05:41.000000,338500000000
2016-07-26 00:06:56.000000,113000000000
2016-07-26 00:06:56.000000,263500000000
2016-07-26 00:08:49.000000,150500000000
2016-07-16 00:00:21.000000,75000000000
2016-07-16 00:00:21.000000,152000000000
2016-07-16 00:00:21.000000,266000000000
2016-07-16 00:00:21.000000,379000000000
2016-07-16 00:00:21.000000,456000000000
2016-07-16 00:00:21.000000,607000000000
2016-07-16 00:01:36.000000,77000000000
2016-07-16 00:01:36.000000,191000000000
2016-07-16 00:01:36.000000,304000000000
2016-07-16 00:01:36.000000,381000000000
2016-07-16 00:01:36.000000,532000000000
2016-07-16 00:02:53.000000,114000000000
2016-07-16 00:02:53.000000,227000000000
2016-07-16 00:02:53.000000,304000000000
2016-07-16 00:02:53.000000,455000000000
2016-07-16 00:04:47.000000,113000000000
2016-07-16 00:04:47.000000,190000000000
2016-07-16 00:04:47.000000,341000000000
2016-07-16 00:06:40.000000,77000000000
2016-07-16 00:06:40.000000,228000000000
2016-07-16 00:07:57.000000,151000000000
2016-07-18 00:00:31.000000,76000000000
2016-07-18 00:00:31.000000,157000000000
2016-07-18 00:00:31.000000,270500000000
2016-07-18 00:00:31.000000,383000000000
2016-07-18 00:00:31.000000,458000000000
2016-07-18 00:00:31.000000,533000000000
2016-07-18 00:00:31.000000,644500000000
2016-07-18 00:00:31.000000,757000000000
2016-07-18 00:00:31.000000,873500000000
2016-07-18 00:00:31.000000,985000000000
2016-07-18 00:01:47.000000,81000000000
2016-07-18 00:01:47.000000,194500000000
2016-07-18 00:01:47.000000,307000000000
2016-07-18 00:01:47.000000,382000000000
2016-07-18 00:01:47.000000,457000000000
2016-07-18 00:01:47.000000,568500000000
2016-07-18 00:01:47.000000,681000000000
2016-07-18 00:01:47.000000,797500000000
2016-07-18 00:01:47.000000,909000000000
2016-07-18 00:03:08.000000,113500000000
2016-07-18 00:03:08.000000,226000000000
2016-07-18 00:03:08.000000,301000000000
2016-07-18 00:03:08.000000,376000000000
2016-07-18 00:03:08.000000,487500000000
2016-07-18 00:03:08.000000,600000000000
2016-07-18 00:03:08.000000,716500000000
2016-07-18 00:03:08.000000,828000000000
2016-07-18 00:05:01.500000,112500000000
2016-07-18 00:05:01.500000,187500000000
2016-07-18 00:05:01.500000,262500000000
2016-07-18 00:05:01.500000,374000000000
2016-07-18 00:05:01.500000,486500000000
2016-07-18 00:05:01.500000,603000000000
2016-07-18 00:05:01.500000,714500000000
2016-07-18 00:06:54.000000,75000000000
2016-07-18 00:06:54.000000,150000000000
2016-07-18 00:06:54.000000,261500000000
2016-07-18 00:06:54.000000,374000000000
2016-07-18 00:06:54.000000,490500000000
2016-07-18 00:06:54.000000,602000000000
2016-07-18 00:08:09.000000,75000000000
2016-07-18 00:08:09.000000,186500000000
2016-07-18 00:08:09.000000,299000000000
2016-07-18 00:08:09.000000,415500000000
2016-07-18 00:08:09.000000,527000000000
2016-07-18 00:09:24.000000,111500000000
2016-07-18 00:09:24.000000,224000000000
2016-07-18 00:09:24.000000,340500000000
2016-07-18 00:09:24.000000,452000000000
2016-07-18 00:11:15.500000,112500000000
2016-07-18 00:11:15.500000,229000000000
2016-07-18 00:11:15.500000,340500000000
2016-07-18 00:13:08.000000,116500000000
2016-07-18 00:13:08.000000,228000000000
2016-07-18 00:15:04.500000,111500000000
2016-07-28 00:00:49.000000,114500000000
2016-07-28 00:00:49.000000,229000000000
2016-07-28 00:00:49.000000,306000000000
2016-07-28 00:00:49.000000,382000000000
2016-07-28 00:00:49.000000,496000000000
2016-07-28 00:00:49.000000,611000000000
2016-07-28 00:00:49.000000,687000000000
2016-07-28 00:02:43.500000,114500000000
2016-07-28 00:02:43.500000,191500000000
2016-07-28 00:02:43.500000,267500000000
2016-07-28 00:02:43.500000,381500000000
2016-07-28 00:02:43.500000,496500000000
2016-07-28 00:02:43.500000,572500000000
2016-07-28 00:04:38.000000,77000000000
2016-07-28 00:04:38.000000,153000000000
2016-07-28 00:04:38.000000,267000000000
2016-07-28 00:04:38.000000,382000000000
2016-07-28 00:04:38.000000,458000000000
2016-07-28 00:05:55.000000,76000000000
2016-07-28 00:05:55.000000,190000000000
2016-07-28 00:05:55.000000,305000000000
2016-07-28 00:05:55.000000,381000000000
2016-07-28 00:07:11.000000,114000000000
2016-07-28 00:07:11.000000,229000000000
2016-07-28 00:07:11.000000,305000000000
2016-07-28 00:09:05.000000,115000000000
2016-07-28 00:09:05.000000,191000000000
2016-07-28 00:11:00.000000,76000000000
2016-12-07 00:01:21.000000,75000000000
2016-12-07 00:01:21.000000,150000000000
2016-12-07 00:01:21.000000,225000000000
2016-12-07 00:01:21.000000,300000000000
2016-12-07 00:01:21.000000,375000000000
2016-12-07 00:01:21.000000,449000000000
2016-12-07 00:01:21.000000,524000000000
2016-12-07 00:01:21.000000,598000000000
2016-12-07 00:02:36.000000,75000000000
2016-12-07 00:02:36.000000,150000000000
2016-12-07 00:02:36.000000,225000000000
2016-12-07 00:02:36.000000,300000000000
2016-12-07 00:02:36.000000,374000000000
2016-12-07 00:02:36.000000,449000000000
2016-12-07 00:02:36.000000,523000000000
2016-12-07 00:03:51.000000,75000000000
2016-12-07 00:03:51.000000,150000000000
2016-12-07 00:03:51.000000,225000000000
2016-12-07 00:03:51.000000,299000000000
2016-12-07 00:03:51.000000,374000000000
2016-12-07 00:03:51.000000,448000000000
2016-12-07 00:05:06.000000,75000000000
2016-12-07 00:05:06.000000,150000000000
2016-12-07 00:05:06.000000,224000000000
2016-12-07 00:05:06.000000,299000000000
2016-12-07 00:05:06.000000,373000000000
2016-12-07 00:06:21.000000,75000000000
2016-12-07 00:06:21.000000,149000000000
2016-12-07 00:06:21.000000,224000000000
2016-12-07 00:06:21.000000,298000000000
2016-12-07 00:07:36.000000,74000000000
2016-12-07 00:07:36.000000,149000000000
2016-12-07 00:07:36.000000,223000000000
2016-12-07 00:08:50.000000,75000000000
2016-12-07 00:08:50.000000,149000000000
2016-12-07 00:10:05.000000,74000000000
2016-07-20 00:02:13.000000,342500000000
2016-07-20 00:02:13.000000,608000000000
2016-07-20 00:07:55.500000,265500000000
2016-07-22 00:00:51.000000,111000000000
2016-07-22 00:00:51.000000,222000000000
2016-07-22 00:00:51.000000,296000000000
2016-07-22 00:00:51.000000,370000000000
2016-07-22 00:00:51.000000,444000000000
2016-07-22 00:00:51.000000,518000000000
2016-07-22 00:00:51.000000,592000000000
2016-07-22 00:00:51.000000,666000000000
2016-07-22 00:02:42.000000,111000000000
2016-07-22 00:02:42.000000,185000000000
2016-07-22 00:02:42.000000,259000000000
2016-07-22 00:02:42.000000,333000000000
2016-07-22 00:02:42.000000,407000000000
2016-07-22 00:02:42.000000,481000000000
2016-07-22 00:02:42.000000,555000000000
2016-07-22 00:04:33.000000,74000000000
2016-07-22 00:04:33.000000,148000000000
2016-07-22 00:04:33.000000,222000000000
2016-07-22 00:04:33.000000,296000000000
2016-07-22 00:04:33.000000,370000000000
2016-07-22 00:04:33.000000,444000000000
2016-07-22 00:05:47.000000,74000000000
2016-07-22 00:05:47.000000,148000000000
2016-07-22 00:05:47.000000,222000000000
2016-07-22 00:05:47.000000,296000000000
2016-07-22 00:05:47.000000,370000000000
2016-07-22 00:07:01.000000,74000000000
2016-07-22 00:07:01.000000,148000000000
2016-07-22 00:07:01.000000,222000000000
2016-07-22 00:07:01.000000,296000000000
2016-07-22 00:08:15.000000,74000000000
2016-07-22 00:08:15.000000,148000000000
2016-07-22 00:08:15.000000,222000000000
2016-07-22 00:09:29.000000,74000000000
2016-07-22 00:09:29.000000,148000000000
2016-07-22 00:10:43.000000,74000000000
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2016-08-07 00:00:24.000000,150000000000
2016-08-07 00:00:24.000000,225000000000
2016-08-07 00:00:24.000000,301000000000
2016-08-07 00:00:24.000000,376000000000
2016-08-07 00:00:24.000000,488500000000
2016-08-07 00:00:24.000000,601000000000
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2016-08-07 00:01:39.000000,75000000000
2016-08-07 00:01:39.000000,150000000000
2016-08-07 00:01:39.000000,226000000000
2016-08-07 00:01:39.000000,301000000000
2016-08-07 00:01:39.000000,413500000000
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2016-08-07 00:01:39.000000,604000000000
2016-08-07 00:02:54.000000,75000000000
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2016-08-07 00:02:54.000000,226000000000
2016-08-07 00:02:54.000000,338500000000
2016-08-07 00:02:54.000000,451000000000
2016-08-07 00:02:54.000000,529000000000
2016-08-07 00:04:09.000000,76000000000
2016-08-07 00:04:09.000000,151000000000
2016-08-07 00:04:09.000000,263500000000
2016-08-07 00:04:09.000000,376000000000
2016-08-07 00:04:09.000000,454000000000
2016-08-07 00:05:25.000000,75000000000
2016-08-07 00:05:25.000000,187500000000
2016-08-07 00:05:25.000000,300000000000
2016-08-07 00:05:25.000000,378000000000
2016-08-07 00:06:40.000000,112500000000
2016-08-07 00:06:40.000000,225000000000
2016-08-07 00:06:40.000000,303000000000
2016-08-07 00:08:32.500000,112500000000
2016-08-07 00:08:32.500000,190500000000
2016-08-07 00:10:25.000000,78000000000
2016-11-07 00:01:41.000000,113000000000
2016-11-07 00:01:41.000000,188000000000
2016-11-07 00:01:41.000000,263000000000
2016-11-07 00:01:41.000000,339000000000
2016-11-07 00:01:41.000000,414000000000
2016-11-07 00:01:41.000000,489000000000
2016-11-07 00:01:41.000000,565000000000
2016-11-07 00:01:41.000000,640000000000
2016-11-07 00:01:41.000000,716000000000
2016-11-07 00:01:41.000000,792000000000
2016-11-07 00:01:41.000000,874000000000
2016-11-07 00:01:41.000000,950000000000
2016-11-07 00:03:34.000000,75000000000
2016-11-07 00:03:34.000000,150000000000
2016-11-07 00:03:34.000000,226000000000
2016-11-07 00:03:34.000000,301000000000
2016-11-07 00:03:34.000000,376000000000
2016-11-07 00:03:34.000000,452000000000
2016-11-07 00:03:34.000000,527000000000
2016-11-07 00:03:34.000000,603000000000
2016-11-07 00:03:34.000000,679000000000
2016-11-07 00:03:34.000000,761000000000
2016-11-07 00:03:34.000000,837000000000
2016-11-07 00:04:49.000000,75000000000
2016-11-07 00:04:49.000000,151000000000
2016-11-07 00:04:49.000000,226000000000
2016-11-07 00:04:49.000000,301000000000
2016-11-07 00:04:49.000000,377000000000
2016-11-07 00:04:49.000000,452000000000
2016-11-07 00:04:49.000000,528000000000
2016-11-07 00:04:49.000000,604000000000
2016-11-07 00:04:49.000000,686000000000
2016-11-07 00:04:49.000000,762000000000
2016-11-07 00:06:04.000000,76000000000
2016-11-07 00:06:04.000000,151000000000
2016-11-07 00:06:04.000000,226000000000
2016-11-07 00:06:04.000000,302000000000
2016-11-07 00:06:04.000000,377000000000
2016-11-07 00:06:04.000000,453000000000
2016-11-07 00:06:04.000000,529000000000
2016-11-07 00:06:04.000000,611000000000
2016-11-07 00:06:04.000000,687000000000
2016-11-07 00:07:20.000000,75000000000
2016-11-07 00:07:20.000000,150000000000
2016-11-07 00:07:20.000000,226000000000
2016-11-07 00:07:20.000000,301000000000
2016-11-07 00:07:20.000000,377000000000
2016-11-07 00:07:20.000000,453000000000
2016-11-07 00:07:20.000000,535000000000
2016-11-07 00:07:20.000000,611000000000
2016-11-07 00:08:35.000000,75000000000
2016-11-07 00:08:35.000000,151000000000
2016-11-07 00:08:35.000000,226000000000
2016-11-07 00:08:35.000000,302000000000
2016-11-07 00:08:35.000000,378000000000
2016-11-07 00:08:35.000000,460000000000
2016-11-07 00:08:35.000000,536000000000
2016-11-07 00:09:50.000000,76000000000
2016-11-07 00:09:50.000000,151000000000
2016-11-07 00:09:50.000000,227000000000
2016-11-07 00:09:50.000000,303000000000
2016-11-07 00:09:50.000000,385000000000
2016-11-07 00:09:50.000000,461000000000
2016-11-07 00:11:06.000000,75000000000
2016-11-07 00:11:06.000000,151000000000
2016-11-07 00:11:06.000000,227000000000
2016-11-07 00:11:06.000000,309000000000
2016-11-07 00:11:06.000000,385000000000
2016-11-07 00:12:21.000000,76000000000
2016-11-07 00:12:21.000000,152000000000
2016-11-07 00:12:21.000000,234000000000
2016-11-07 00:12:21.000000,310000000000
2016-11-07 00:13:37.000000,76000000000
2016-11-07 00:13:37.000000,158000000000
2016-11-07 00:13:37.000000,234000000000
2016-11-07 00:14:53.000000,82000000000
2016-11-07 00:14:53.000000,158000000000
2016-11-07 00:16:15.000000,76000000000
2016-07-19 00:01:12.000000,75000000000
2016-07-19 00:01:12.000000,151000000000
2016-07-19 00:01:12.000000,226000000000
2016-07-19 00:01:12.000000,303000000000
2016-07-19 00:01:12.000000,379000000000
2016-07-19 00:01:12.000000,454000000000
2016-07-19 00:01:12.000000,530000000000
2016-07-19 00:01:12.000000,605000000000
2016-07-19 00:01:12.000000,680000000000
2016-07-19 00:02:27.000000,76000000000
2016-07-19 00:02:27.000000,151000000000
2016-07-19 00:02:27.000000,228000000000
2016-07-19 00:02:27.000000,304000000000
2016-07-19 00:02:27.000000,379000000000
2016-07-19 00:02:27.000000,455000000000
2016-07-19 00:02:27.000000,530000000000
2016-07-19 00:02:27.000000,605000000000
2016-07-19 00:03:43.000000,75000000000
2016-07-19 00:03:43.000000,152000000000
2016-07-19 00:03:43.000000,228000000000
2016-07-19 00:03:43.000000,303000000000
2016-07-19 00:03:43.000000,379000000000
2016-07-19 00:03:43.000000,454000000000
2016-07-19 00:03:43.000000,529000000000
2016-07-19 00:04:58.000000,77000000000
2016-07-19 00:04:58.000000,153000000000
2016-07-19 00:04:58.000000,228000000000
2016-07-19 00:04:58.000000,304000000000
2016-07-19 00:04:58.000000,379000000000
2016-07-19 00:04:58.000000,454000000000
2016-07-19 00:06:15.000000,76000000000
2016-07-19 00:06:15.000000,151000000000
2016-07-19 00:06:15.000000,227000000000
2016-07-19 00:06:15.000000,302000000000
2016-07-19 00:06:15.000000,377000000000
2016-07-19 00:07:31.000000,75000000000
2016-07-19 00:07:31.000000,151000000000
2016-07-19 00:07:31.000000,226000000000
2016-07-19 00:07:31.000000,301000000000
2016-07-19 00:08:46.000000,76000000000
2016-07-19 00:08:46.000000,151000000000
2016-07-19 00:08:46.000000,226000000000
2016-07-19 00:10:02.000000,75000000000
2016-07-19 00:10:02.000000,150000000000
2016-07-19 00:11:17.000000,75000000000
2016-11-07 00:07:57.583333,497416667000
2016-11-07 00:07:57.583333,573416667000
2016-11-07 00:16:15.000000,76000000000
2016-12-07 00:00:42.000000,114000000000
2016-12-07 00:00:42.000000,264000000000
2016-12-07 00:02:36.000000,150000000000
2016-07-25 00:07:33.300000,421700000000
2016-07-25 00:07:33.300000,497700000000
2016-07-25 00:07:33.300000,573700000000
2016-07-25 00:14:35.000000,76000000000
2016-07-25 00:14:35.000000,152000000000
2016-07-25 00:15:51.000000,76000000000
2016-07-17 00:00:39.000000,75000000000
2016-07-17 00:00:39.000000,150000000000
2016-07-17 00:00:39.000000,225000000000
2016-07-17 00:00:39.000000,300000000000
2016-07-17 00:00:39.000000,374000000000
2016-07-17 00:00:39.000000,449000000000
2016-07-17 00:00:39.000000,524000000000
2016-07-17 00:00:39.000000,635500000000
2016-07-17 00:00:39.000000,747000000000
2016-07-17 00:01:54.000000,75000000000
2016-07-17 00:01:54.000000,150000000000
2016-07-17 00:01:54.000000,225000000000
2016-07-17 00:01:54.000000,299000000000
2016-07-17 00:01:54.000000,374000000000
2016-07-17 00:01:54.000000,449000000000
2016-07-17 00:01:54.000000,560500000000
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2016-07-17 00:05:39.000000,224000000000
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2016-07-24 00:00:30.000000,76000000000
2016-07-24 00:00:30.000000,152000000000
2016-07-24 00:00:30.000000,227000000000
2016-07-24 00:00:30.000000,303000000000
2016-07-24 00:00:30.000000,378000000000
2016-07-24 00:00:30.000000,454000000000
2016-07-24 00:00:30.000000,529000000000
2016-07-24 00:00:30.000000,605000000000
2016-07-24 00:00:30.000000,680000000000
2016-07-24 00:00:30.000000,755000000000
2016-07-24 00:01:46.000000,76000000000
2016-07-24 00:01:46.000000,151000000000
2016-07-24 00:01:46.000000,227000000000
2016-07-24 00:01:46.000000,302000000000
2016-07-24 00:01:46.000000,378000000000
2016-07-24 00:01:46.000000,453000000000
2016-07-24 00:01:46.000000,529000000000
2016-07-24 00:01:46.000000,604000000000
2016-07-24 00:01:46.000000,679000000000
2016-07-24 00:03:02.000000,75000000000
2016-07-24 00:03:02.000000,151000000000
2016-07-24 00:03:02.000000,226000000000
2016-07-24 00:03:02.000000,302000000000
2016-07-24 00:03:02.000000,377000000000
2016-07-24 00:03:02.000000,453000000000
2016-07-24 00:03:02.000000,528000000000
2016-07-24 00:03:02.000000,603000000000
2016-07-24 00:04:17.000000,76000000000
2016-07-24 00:04:17.000000,151000000000
2016-07-24 00:04:17.000000,227000000000
2016-07-24 00:04:17.000000,302000000000
2016-07-24 00:04:17.000000,378000000000
2016-07-24 00:04:17.000000,453000000000
2016-07-24 00:04:17.000000,528000000000
2016-07-24 00:05:33.000000,75000000000
2016-07-24 00:05:33.000000,151000000000
2016-07-24 00:05:33.000000,226000000000
2016-07-24 00:05:33.000000,302000000000
2016-07-24 00:05:33.000000,377000000000
2016-07-24 00:05:33.000000,452000000000
2016-07-24 00:06:48.000000,76000000000
2016-07-24 00:06:48.000000,151000000000
2016-07-24 00:06:48.000000,227000000000
2016-07-24 00:06:48.000000,302000000000
2016-07-24 00:06:48.000000,377000000000
2016-07-24 00:08:04.000000,75000000000
2016-07-24 00:08:04.000000,151000000000
2016-07-24 00:08:04.000000,226000000000
2016-07-24 00:08:04.000000,301000000000
2016-07-24 00:09:19.000000,76000000000
2016-07-24 00:09:19.000000,151000000000
2016-07-24 00:09:19.000000,226000000000
2016-07-24 00:10:35.000000,75000000000
2016-07-24 00:10:35.000000,150000000000
2016-07-24 00:11:50.000000,75000000000
2016-07-26 00:01:17.000000,113000000000
2016-07-26 00:01:17.000000,189000000000
2016-07-26 00:03:10.000000,76000000000

[prcastro]

Using the data sample above as sample.csv, I get:

>>> df = pd.read_csv('sample.csv', parse_dates=['timestamp'], index_col='timestamp')


>>> df.groupby(pd.Grouper(freq='H')).agg({'value': 'mean'})
                            value
timestamp
2016-06-07 00:00:00  2.729111e+11
2016-06-07 01:00:00           NaN
2016-06-07 02:00:00           NaN
2016-06-07 03:00:00           NaN
2016-06-07 04:00:00           NaN
...



>>> df.groupby([pd.Grouper(freq='H')]).agg({'value': 'mean'})
                   value
timestamp
2016-06-07  2.729111e+11
2016-07-07  2.509444e+11
2016-07-13  2.775778e+11
2016-07-15  2.490556e+11
2016-07-16  2.676190e+11
...

[jreback]

ok, your example repros. If you can step thru both the working and non-working cases (as well as df.resample('H').value.mean() these should all be the same, and see if you can pinpoint the problem.

[jreback]

closing as duplicate of #17530