title: Average function in PostgreSQL with 5 minutes tolerance
body: <p>I have a temporal database and I want to aggregate by the average function every HH instantaneous values with 5 minute before and 5 minute after. Frequency of data samplying is 2 minutes and the data includes timestamps and temperature columns.
  First of all, the code should extract the instantaneous values from 00, 01, 02, 03, ... 24 and then apply 2 observation of before and 2 observations of after the instantaneous hours.
   Moreover, in db sometimes minutes are odd and sometimes they are even. So, we have both HH-1:59 and HH:00 . The average value obtains from mean of 5 values. The format of the date_time column is timestamps. Moreover the code should can handle multiple days data.</p>
  
  <p>Sample data:</p>
  
  <pre><code>   dt          ambtemp
         "2007-09-29 00:11:09+02";-1.87
      "2007-09-29 00:13:09+02";-1.87
      "2007-09-29 00:15:09+02";-1.8
      "2007-09-29 00:17:09+02";-1.64
      "2007-09-29 00:19:09+02";-1.6
      "2007-09-29 00:21:09+02";-1.9
      "2007-09-29 00:23:09+02";-2.08
      "2007-09-29 00:25:09+02";-1.94
      "2007-09-29 00:27:09+02";-2.12
      "2007-09-29 00:29:09+02";-1.87
      "2007-09-29 00:31:09+02";-2.18
      "2007-09-29 00:33:09+02";-1.98
      "2007-09-29 00:35:09+02";-1.73
      "2007-09-29 00:37:09+02";-1.84
      "2007-09-29 00:39:09+02";-2.04
      "2007-09-29 00:41:09+02";-1.86
      "2007-09-29 00:43:09+02";-1.94
      "2007-09-29 00:45:09+02";-1.77
      "2007-09-29 00:47:09+02";-1.78
      "2007-09-29 00:49:09+02";-1.5
      "2007-09-29 00:51:09+02";-1.46
      "2007-09-29 00:53:09+02";-1.72
      "2007-09-29 00:55:09+02";-1.67
      "2007-09-29 00:57:09+02";-1.56
      "2007-09-29 00:59:09+02";-1.69
      "2007-09-29 01:01:09+02";-1.97
      "2007-09-29 01:03:09+02";-1.79
      "2007-09-29 01:05:09+02";-1.79
      "2007-09-29 01:07:09+02";-1.84
      "2007-09-29 01:09:09+02";-1.91
      "2007-09-29 01:11:09+02";-1.87
      "2007-09-29 01:13:09+02";-1.98
      "2007-09-29 01:15:09+02";-1.83
      "2007-09-29 01:17:09+02";-1.88
      "2007-09-29 01:19:09+02";-1.88
      "2007-09-29 01:21:09+02";-1.78
      "2007-09-29 01:23:09+02";-1.78
      "2007-09-29 01:25:09+02";-1.66
      "2007-09-29 01:27:09+02";-1.7
      "2007-09-29 01:29:09+02";-1.46
      "2007-09-29 01:31:09+02";-1.36
      "2007-09-29 01:33:09+02";-1.4
      "2007-09-29 01:35:09+02";-1.34
      "2007-09-29 01:37:09+02";-1.34
      "2007-09-29 01:39:09+02";-1.3
      "2007-09-29 01:41:09+02";-1.36
      "2007-09-29 01:43:09+02";-1.4
      "2007-09-29 01:45:09+02";-1.43
      "2007-09-29 01:47:09+02";-1.38
      "2007-09-29 01:49:09+02";-1.4
      "2007-09-29 01:51:09+02";-1.42
      "2007-09-29 01:53:09+02";-1.47
      "2007-09-29 01:55:09+02";-1.66
      "2007-09-29 01:57:09+02";-1.84
      "2007-09-29 01:59:09+02";-1.92
      "2007-09-29 02:01:09+02";-1.88
      "2007-09-29 02:03:09+02";-2.11
      "2007-09-29 02:05:09+02";-1.91
      "2007-09-29 02:07:09+02";-2.04
      "2007-09-29 02:09:09+02";-1.94
      "2007-09-29 02:11:09+02";-1.92
      "2007-09-29 02:13:09+02";-1.8
      "2007-09-29 02:15:09+02";-1.74
      "2007-09-29 02:17:09+02";-1.74
      "2007-09-29 02:19:09+02";-1.76
      "2007-09-29 02:21:09+02";-1.74
      "2007-09-29 02:23:09+02";-1.8
      "2007-09-29 02:25:09+02";-1.8
      "2007-09-29 02:27:09+02";-1.8
      "2007-09-29 02:29:09+02";-1.82
      "2007-09-29 02:31:09+02";-1.9
      "2007-09-29 02:33:09+02";-1.93
      "2007-09-29 02:35:09+02";-2.06
      "2007-09-29 02:37:09+02";-2.08
      "2007-09-29 02:39:09+02";-1.95
      "2007-09-29 02:41:09+02";-1.98
      "2007-09-29 02:43:09+02";-2.32
      "2007-09-29 02:45:09+02";-1.86
      "2007-09-29 02:47:09+02";-1.97
      "2007-09-29 02:49:09+02";-1.64
      "2007-09-29 02:51:09+02";-2
      "2007-09-29 02:53:09+02";-1.48
      "2007-09-29 02:55:09+02";-1.74
      "2007-09-29 02:57:09+02";-1.85
      "2007-09-29 02:59:09+02";-1.82
      "2007-09-29 03:01:09+02";-1.82
      "2007-09-29 03:03:09+02";-1.92
      "2007-09-29 03:05:09+02";-1.8
      "2007-09-29 03:07:09+02";-1.54
      "2007-09-29 03:09:09+02";-1.36
      "2007-09-29 03:11:09+02";-1.5
      "2007-09-29 03:13:09+02";-1.59
      "2007-09-29 03:15:09+02";-1.6
      "2007-09-29 03:17:09+02";-1.58
      "2007-09-29 03:19:09+02";-1.81
      "2007-09-29 03:21:09+02";-2.16
      "2007-09-29 03:23:09+02";-1.97
      "2007-09-29 03:25:09+02";-1.94
      "2007-09-29 03:27:09+02";-2.29
      "2007-09-29 03:29:09+02";-2.46
      "2007-09-29 03:31:09+02";-2.42
      "2007-09-29 03:33:09+02";-2.34
      "2007-09-29 03:35:09+02";-2.38
      "2007-09-29 03:37:09+02";-2.44
      "2007-09-29 03:39:09+02";-2.28
      "2007-09-29 03:41:09+02";-2.24
      "2007-09-29 03:43:09+02";-2.26
      "2007-09-29 03:45:09+02";-2.05
      "2007-09-29 03:47:09+02";-2.38
      "2007-09-29 03:49:09+02";-2.24
      "2007-09-29 03:51:09+02";-2.46
      "2007-09-29 03:53:09+02";-2.22
      "2007-09-29 03:55:09+02";-2.24
      "2007-09-29 03:57:09+02";-2.2
      "2007-09-29 03:59:09+02";-2.28
      "2007-09-29 04:01:09+02";-1.86
      "2007-09-29 04:03:09+02";-1.9
      "2007-09-29 04:05:09+02";-1.98
      "2007-09-29 04:07:09+02";-1.99
      "2007-09-29 04:09:09+02";-2
      "2007-09-29 04:11:09+02";-1.98
      "2007-09-29 04:13:09+02";-2.13
      "2007-09-29 04:15:09+02";-2.11
      "2007-09-29 04:17:09+02";-2.1
      "2007-09-29 04:19:09+02";-2.28
      "2007-09-29 04:21:09+02";-2.28
      "2007-09-29 04:23:09+02";-2.44
      "2007-09-29 04:25:09+02";-2.44
      "2007-09-29 04:27:08+02";-2.2
      "2007-09-29 04:29:08+02";-2.2
      "2007-09-29 04:31:08+02";-2.11
      "2007-09-29 04:31:09+02";-2.11
      "2007-09-29 04:33:09+02";-2.3
      "2007-09-29 04:35:09+02";-2
      "2007-09-29 04:37:08+02";-1.7
      "2007-09-29 04:39:08+02";-1.43
      "2007-09-29 04:41:08+02";-1.55
      "2007-09-29 04:43:09+02";-1.43
      "2007-09-29 04:45:09+02";-1.59
      "2007-09-29 04:47:08+02";-1.58
      "2007-09-29 04:49:08+02";-1.52
      "2007-09-29 04:51:08+02";-1.5
      "2007-09-29 04:53:09+02";-1.4
      "2007-09-29 04:55:08+02";-1.46
      "2007-09-29 04:55:09+02";-1.46
      "2007-09-29 04:57:08+02";-1.5
      "2007-09-29 04:59:08+02";-1.52
      "2007-09-29 05:01:08+02";-1.64
      "2007-09-29 05:03:08+02";-1.7
      "2007-09-29 05:05:08+02";-1.7
      "2007-09-29 05:07:08+02";-1.71
      "2007-09-29 05:09:08+02";-1.96
      "2007-09-29 05:11:08+02";-2.03
      "2007-09-29 05:13:08+02";-2.18
      "2007-09-29 05:15:08+02";-2.2
      "2007-09-29 05:17:08+02";-1.91
      "2007-09-29 05:19:08+02";-2.06
      "2007-09-29 05:21:08+02";-2
      "2007-09-29 05:23:08+02";-1.92
      "2007-09-29 05:25:08+02";-2
      "2007-09-29 05:27:08+02";-1.86
      "2007-09-29 05:29:08+02";-2.08
      "2007-09-29 05:31:08+02";-2.03
      "2007-09-29 05:33:08+02";-1.83
      "2007-09-29 05:35:08+02";-1.7
      "2007-09-29 05:37:08+02";-1.7
      "2007-09-29 05:39:08+02";-1.6
      "2007-09-29 05:41:08+02";-1.64
      "2007-09-29 05:43:08+02";-1.65
      "2007-09-29 05:45:08+02";-1.67
      "2007-09-29 05:47:08+02";-1.8
      "2007-09-29 05:49:08+02";-1.82
      "2007-09-29 05:51:08+02";-1.88
      "2007-09-29 05:53:08+02";-1.91
      "2007-09-29 05:55:08+02";-1.92
      "2007-09-29 05:57:08+02";-1.93
      "2007-09-29 05:59:08+02";-1.9
      "2007-09-29 06:01:08+02";-2.04
      "2007-09-29 06:03:08+02";-1.98
      "2007-09-29 06:05:08+02";-1.96
      "2007-09-29 06:07:08+02";-1.98
      "2007-09-29 06:09:08+02";-1.93
      "2007-09-29 06:11:08+02";-1.78
      "2007-09-29 06:13:08+02";-1.73
      "2007-09-29 06:15:08+02";-1.76
      "2007-09-29 06:17:08+02";-1.67
      "2007-09-29 06:19:08+02";-1.68
      "2007-09-29 06:21:08+02";-1.38
      "2007-09-29 06:23:08+02";-1.33
      "2007-09-29 06:25:07+02";-1.31
      "2007-09-29 06:27:08+02";-1.34
      "2007-09-29 06:29:08+02";-1.28
      "2007-09-29 06:31:08+02";-1.28
      "2007-09-29 06:33:07+02";-1.51
      "2007-09-29 06:35:08+02";-1.76
      "2007-09-29 06:37:08+02";-1.84
      "2007-09-29 06:39:08+02";-1.89
      "2007-09-29 06:41:08+02";-1.98
      "2007-09-29 06:43:08+02";-2
      "2007-09-29 06:45:08+02";-2
      "2007-09-29 06:47:08+02";-1.96
      "2007-09-29 06:49:08+02";-1.92
      "2007-09-29 06:51:08+02";-1.88
      "2007-09-29 06:53:07+02";-1.79
      "2007-09-29 06:55:07+02";-1.73
      "2007-09-29 06:57:08+02";-1.7
      "2007-09-29 06:59:07+02";-1.72
      "2007-09-29 07:01:08+02";-1.74
      "2007-09-29 07:03:08+02";-1.8
      "2007-09-29 07:05:08+02";-1.8
      "2007-09-29 07:07:08+02";-1.84
      "2007-09-29 07:09:08+02";-1.88
      "2007-09-29 07:11:08+02";-1.89
      "2007-09-29 07:13:08+02";-1.92
      "2007-09-29 07:15:08+02";-1.92
      "2007-09-29 07:17:08+02";-1.96
      "2007-09-29 07:19:07+02";-1.98
      "2007-09-29 07:21:08+02";-2
      "2007-09-29 07:23:07+02";-1.96
      "2007-09-29 07:25:08+02";-1.94
      "2007-09-29 07:27:08+02";-1.92
      "2007-09-29 07:29:07+02";-1.92
      "2007-09-29 07:31:08+02";-1.92
      "2007-09-29 07:33:08+02";-1.92
      "2007-09-29 07:35:08+02";-1.94
      "2007-09-29 07:37:08+02";-1.9
      "2007-09-29 07:39:08+02";-1.92
      "2007-09-29 07:41:08+02";-1.9
      "2007-09-29 07:43:07+02";-1.9
      "2007-09-29 07:45:08+02";-1.88
      "2007-09-29 07:47:08+02";-1.85
      "2007-09-29 07:49:08+02";-1.86
      "2007-09-29 07:51:07+02";-1.87
      "2007-09-29 07:53:08+02";-1.72
      "2007-09-29 07:55:08+02";-1.55
      "2007-09-29 07:57:08+02";-1.52
      "2007-09-29 07:59:08+02";-1.53
      "2007-09-29 08:01:08+02";-1.54
      "2007-09-29 08:03:08+02";-1.6
      "2007-09-29 08:05:08+02";-1.77
      "2007-09-29 08:07:08+02";-1.8
      "2007-09-29 08:09:08+02";-1.8
      "2007-09-29 08:11:08+02";-1.8
      "2007-09-29 08:13:08+02";-1.96
      "2007-09-29 08:15:09+02";-1.88
      "2007-09-29 08:17:08+02";-1.44
      "2007-09-29 08:19:08+02";-1.34
      "2007-09-29 08:21:08+02";-1.22
      "2007-09-29 08:23:08+02";-1.34
      "2007-09-29 08:25:09+02";-1.24
      "2007-09-29 08:27:09+02";-0.66
      "2007-09-29 08:29:09+02";-0.98
      "2007-09-29 08:31:09+02";-1.1
      "2007-09-29 08:33:08+02";0.1
      "2007-09-29 08:35:09+02";0.27
      "2007-09-29 08:37:09+02";-0.14
      "2007-09-29 08:39:08+02";-0.52
      "2007-09-29 08:41:08+02";-1
      "2007-09-29 08:43:08+02";-0.58
      "2007-09-29 08:45:08+02";-0.7
      "2007-09-29 08:47:08+02";-0.6
      "2007-09-29 08:49:08+02";-0.87
      "2007-09-29 08:51:08+02";-0.44
      "2007-09-29 08:53:08+02";-0.69
      "2007-09-29 08:55:08+02";-0.14
      "2007-09-29 08:57:08+02";0.12
      "2007-09-29 08:59:08+02";-0.37
      "2007-09-29 09:01:08+02";0.32
      "2007-09-29 09:03:07+02";0.04
      "2007-09-29 09:05:07+02";0.3
      "2007-09-29 09:07:07+02";0.32
      "2007-09-29 09:09:07+02";-0.2
      "2007-09-29 09:11:07+02";-0.07
      "2007-09-29 09:13:07+02";0.11
      "2007-09-29 09:15:07+02";0.34
      "2007-09-29 09:17:07+02";0.58
      "2007-09-29 09:19:07+02";0.46
      "2007-09-29 09:21:07+02";-0.27
      "2007-09-29 09:23:07+02";-0.57
      "2007-09-29 09:25:07+02";-0.2
      "2007-09-29 09:27:07+02";0
      "2007-09-29 09:29:07+02";-0.04
      "2007-09-29 09:31:07+02";-0.77
      "2007-09-29 09:33:07+02";-0.3
      "2007-09-29 09:35:07+02";0.34
      "2007-09-29 09:37:07+02";0.1
      "2007-09-29 09:39:07+02";0.05
      "2007-09-29 09:41:07+02";0.18
      "2007-09-29 09:43:07+02";1.2
      "2007-09-29 09:45:07+02";1.84
      "2007-09-29 09:47:07+02";0.93
      "2007-09-29 09:49:07+02";0.58
      "2007-09-29 09:51:07+02";-0.22
      "2007-09-29 09:53:07+02";0.09
      "2007-09-29 09:55:07+02";0.28
      "2007-09-29 09:57:07+02";1.4
      "2007-09-29 09:59:07+02";1.38
      "2007-09-29 10:01:07+02";2
      "2007-09-29 10:03:07+02";2.16
      "2007-09-29 10:05:07+02";2.48
      "2007-09-29 10:07:07+02";2.8
      "2007-09-29 10:09:07+02";1.66
      "2007-09-29 10:11:07+02";1.56
      "2007-09-29 10:13:07+02";1.49
      "2007-09-29 10:15:07+02";0.86
      "2007-09-29 10:17:07+02";1.37
      "2007-09-29 10:19:07+02";1.16
      "2007-09-29 10:21:07+02";1.16
      "2007-09-29 10:23:07+02";1.6
      "2007-09-29 10:25:07+02";0.84
      "2007-09-29 10:27:07+02";2.14
      "2007-09-29 10:29:07+02";2.25
      "2007-09-29 10:31:07+02";2.25
      "2007-09-29 10:33:07+02";2.12
      "2007-09-29 10:35:07+02";1.68
      "2007-09-29 10:37:07+02";2.14
      "2007-09-29 10:39:07+02";1.1
      "2007-09-29 10:41:07+02";1.23
      "2007-09-29 10:43:07+02";1.4
      "2007-09-29 10:45:07+02";1.78
      "2007-09-29 10:47:07+02";1.36
      "2007-09-29 10:49:07+02";2.26
      "2007-09-29 10:51:07+02";1.8
      "2007-09-29 10:53:07+02";2.08
      "2007-09-29 10:55:07+02";1.96
      "2007-09-29 10:57:07+02";2.46
      "2007-09-29 10:59:07+02";2.69
      "2007-09-29 11:01:07+02";2.24
      "2007-09-29 11:03:07+02";1.59
      "2007-09-29 11:05:07+02";1.74
      "2007-09-29 11:07:07+02";1.38
      "2007-09-29 11:09:07+02";1.97
      "2007-09-29 11:11:07+02";2.06
      "2007-09-29 11:13:07+02";1.64
      "2007-09-29 11:15:07+02";2.22
      "2007-09-29 11:17:07+02";3.07
      "2007-09-29 11:19:07+02";1.98
      "2007-09-29 11:21:07+02";2.88
      "2007-09-29 11:23:07+02";2.9
      "2007-09-29 11:25:07+02";1.62
      "2007-09-29 11:27:07+02";1.79
      "2007-09-29 11:29:07+02";2.7
      "2007-09-29 11:31:07+02";1.96
      "2007-09-29 11:33:07+02";2.9
      "2007-09-29 11:35:07+02";2.76
      "2007-09-29 11:37:07+02";2.08
      "2007-09-29 11:39:07+02";2.88
      "2007-09-29 11:41:07+02";2.55
      "2007-09-29 11:43:07+02";2.49
      "2007-09-29 11:45:07+02";2.52
      "2007-09-29 11:47:07+02";2.68
      "2007-09-29 11:49:07+02";3.1
      "2007-09-29 11:51:07+02";3.72
      "2007-09-29 11:53:07+02";2.94
      "2007-09-29 11:55:07+02";3.86
      "2007-09-29 11:57:07+02";3.76
      "2007-09-29 11:59:07+02";2.8
      "2007-09-29 12:01:07+02";2.28
      "2007-09-29 12:03:07+02";2.8
      "2007-09-29 12:05:07+02";3.1
      "2007-09-29 12:07:07+02";2.63
      "2007-09-29 12:09:07+02";2.76
      "2007-09-29 12:11:07+02";4.02
      "2007-09-29 12:13:07+02";3.47
      "2007-09-29 12:15:07+02";3.2
      "2007-09-29 12:17:07+02";2.65
      "2007-09-29 12:19:07+02";4.11
      "2007-09-29 12:21:07+02";2.66
      "2007-09-29 12:23:07+02";4.34
      "2007-09-29 12:25:07+02";4.1
      "2007-09-29 12:27:07+02";4.17
      "2007-09-29 12:29:07+02";3.16
      "2007-09-29 12:31:07+02";3.98
      "2007-09-29 12:33:07+02";3.72
      "2007-09-29 12:35:07+02";3.66
      "2007-09-29 12:37:07+02";3.26
      "2007-09-29 12:39:07+02";4.5
      "2007-09-29 12:41:07+02";3.94
      "2007-09-29 12:43:07+02";4.11
      "2007-09-29 12:45:07+02";3.89
      "2007-09-29 12:47:06+02";3.22
      "2007-09-29 12:49:06+02";4.26
      "2007-09-29 12:51:06+02";4.98
      "2007-09-29 12:53:06+02";4.46
      "2007-09-29 12:55:06+02";4.86
      "2007-09-29 12:57:07+02";3.91
      "2007-09-29 12:59:07+02";3.56
      "2007-09-29 13:01:07+02";5.27
      "2007-09-29 13:03:07+02";4.12
      "2007-09-29 13:05:07+02";5.07
      "2007-09-29 13:07:06+02";4.16
      "2007-09-29 13:09:06+02";4.56
      "2007-09-29 13:11:06+02";4.24
      "2007-09-29 13:13:06+02";4.34
      "2007-09-29 13:15:06+02";4.63
      "2007-09-29 13:17:06+02";4.68
      "2007-09-29 13:19:06+02";3.71
      "2007-09-29 13:21:06+02";3.79
      "2007-09-29 13:23:06+02";4.61
      "2007-09-29 13:25:06+02";4.95
      "2007-09-29 13:27:06+02";4.66
      "2007-09-29 13:29:06+02";4.32
      "2007-09-29 13:31:06+02";3.98
      "2007-09-29 13:33:06+02";5.43
      "2007-09-29 13:35:06+02";4.38
      "2007-09-29 13:37:06+02";4.39
      "2007-09-29 13:39:06+02";4.7
      "2007-09-29 13:41:06+02";4.34
      "2007-09-29 13:43:06+02";5.56
      "2007-09-29 13:45:06+02";4.61
      "2007-09-29 13:47:06+02";4.58
      "2007-09-29 13:49:06+02";4.81
      "2007-09-29 13:51:06+02";5.04
      "2007-09-29 13:53:06+02";5.74
      "2007-09-29 13:55:06+02";4.92
      "2007-09-29 13:57:06+02";4.65
      "2007-09-29 13:59:06+02";5.08
      "2007-09-29 14:01:06+02";4.9
      "2007-09-29 14:03:06+02";4.34
      "2007-09-29 14:05:06+02";5.42
      "2007-09-29 14:07:06+02";5.58
      "2007-09-29 14:09:06+02";4.98
      "2007-09-29 14:11:06+02";4.91
      "2007-09-29 14:13:06+02";5.44
      "2007-09-29 14:15:06+02";4.62
      "2007-09-29 14:17:06+02";5.36
      "2007-09-29 14:19:06+02";4.56
      "2007-09-29 14:21:06+02";4.77
      "2007-09-29 14:23:06+02";4.88
      "2007-09-29 14:25:06+02";4.29
      "2007-09-29 14:27:06+02";4.43
      "2007-09-29 14:29:06+02";4.78
      "2007-09-29 14:31:06+02";5.06
      "2007-09-29 14:33:06+02";4.83
      "2007-09-29 14:35:06+02";4.44
      "2007-09-29 14:37:06+02";5.48
      "2007-09-29 14:39:06+02";4.9
      "2007-09-29 14:41:06+02";4.42
      "2007-09-29 14:43:06+02";4.82
      "2007-09-29 14:45:06+02";4.9
      "2007-09-29 14:47:06+02";4.76
      "2007-09-29 14:49:06+02";5.48
      "2007-09-29 14:51:06+02";5.48
      "2007-09-29 14:53:06+02";5.46
      "2007-09-29 14:55:06+02";5.54
      "2007-09-29 14:57:06+02";5.53
      "2007-09-29 14:59:06+02";5.5
      "2007-09-29 15:01:06+02";5.33
      "2007-09-29 15:03:06+02";6.18
      "2007-09-29 15:05:06+02";4.91
      "2007-09-29 15:07:06+02";5.08
      "2007-09-29 15:09:06+02";4.71
      "2007-09-29 15:11:06+02";4.49
      "2007-09-29 15:13:06+02";5.47
      "2007-09-29 15:15:06+02";4.58
      "2007-09-29 15:17:06+02";4.75
      "2007-09-29 15:19:06+02";5.46
      "2007-09-29 15:21:06+02";5.39
      "2007-09-29 15:23:06+02";5.59
      "2007-09-29 15:25:06+02";5.76
      "2007-09-29 15:27:06+02";5.08
      "2007-09-29 15:29:06+02";5.96
      "2007-09-29 15:31:06+02";4.9
      "2007-09-29 15:33:06+02";5.36
      "2007-09-29 15:35:06+02";5.08
      "2007-09-29 15:37:06+02";5.93
      "2007-09-29 15:39:06+02";5.34
      "2007-09-29 15:41:06+02";5.24
      "2007-09-29 15:43:06+02";5.78
      "2007-09-29 15:45:06+02";6.58
      "2007-09-29 15:47:06+02";6.09
      "2007-09-29 15:49:06+02";5.4
      "2007-09-29 15:51:06+02";6.18
      "2007-09-29 15:53:06+02";5.79
      "2007-09-29 15:55:06+02";5.36
      "2007-09-29 15:57:06+02";5.8
      "2007-09-29 15:59:07+02";6.06
      "2007-09-29 16:01:06+02";5.7
      "2007-09-29 16:03:07+02";5.58
      "2007-09-29 16:05:07+02";6.5
      "2007-09-29 16:07:07+02";5.83
      "2007-09-29 16:09:07+02";5.54
      "2007-09-29 16:11:06+02";5.8
      "2007-09-29 16:13:06+02";6.03
      "2007-09-29 16:15:06+02";5.54
      "2007-09-29 16:17:07+02";5.56
      "2007-09-29 16:19:07+02";6.04
      "2007-09-29 16:21:07+02";5.74
      "2007-09-29 16:23:06+02";5.4
      "2007-09-29 16:25:07+02";6.39
      "2007-09-29 16:27:07+02";6.64
      "2007-09-29 16:29:07+02";6.3
      "2007-09-29 16:31:07+02";5.86
      "2007-09-29 16:33:07+02";5.62
      "2007-09-29 16:35:07+02";6.29
      "2007-09-29 16:37:07+02";5.24
      "2007-09-29 16:39:07+02";5.92
      "2007-09-29 16:41:07+02";5.68
      "2007-09-29 16:43:07+02";6.2
      "2007-09-29 16:45:07+02";6.53
      "2007-09-29 16:47:06+02";5.44
      "2007-09-29 16:49:06+02";5.58
      "2007-09-29 16:51:07+02";4.68
      "2007-09-29 16:53:07+02";6.36
      "2007-09-29 16:55:07+02";5.46
      "2007-09-29 16:57:06+02";5.4
      "2007-09-29 16:59:06+02";5.84
      "2007-09-29 17:01:06+02";6.12
      "2007-09-29 17:03:06+02";6.28
      "2007-09-29 17:05:06+02";5.48
      "2007-09-29 17:07:06+02";4.67
      "2007-09-29 17:09:06+02";4.69
      "2007-09-29 17:11:06+02";4.36
      "2007-09-29 17:13:06+02";4.6
      "2007-09-29 17:15:06+02";4.86
      "2007-09-29 17:17:06+02";4.52
      "2007-09-29 17:19:06+02";4.04
      "2007-09-29 17:21:06+02";3.98
      "2007-09-29 17:23:06+02";3.8
      "2007-09-29 17:25:06+02";3.76
      "2007-09-29 17:27:06+02";3.44
      "2007-09-29 17:29:06+02";3.44
      "2007-09-29 17:31:06+02";3.45
      "2007-09-29 17:33:06+02";3.64
      "2007-09-29 17:35:06+02";3.62
      "2007-09-29 17:37:06+02";3.43
      "2007-09-29 17:39:06+02";3.52
      "2007-09-29 17:41:06+02";3.31
      "2007-09-29 17:43:06+02";3.13
      "2007-09-29 17:45:06+02";3.21
      "2007-09-29 17:47:06+02";3.26
      "2007-09-29 17:49:06+02";3.17
      "2007-09-29 17:51:06+02";3.05
      "2007-09-29 17:53:06+02";2.86
      "2007-09-29 17:55:06+02";2.84
      "2007-09-29 17:57:06+02";2.79
      "2007-09-29 17:59:06+02";2.6
      "2007-09-29 18:01:06+02";2.54
      "2007-09-29 18:03:06+02";2.51
      "2007-09-29 18:05:06+02";2.54
      "2007-09-29 18:07:06+02";2.6
      "2007-09-29 18:09:06+02";2.5
      "2007-09-29 18:11:06+02";2.25
      "2007-09-29 18:13:06+02";2.26
      "2007-09-29 18:15:06+02";2.28
      "2007-09-29 18:17:06+02";1.95
      "2007-09-29 18:19:06+02";1.9
      "2007-09-29 18:21:06+02";1.8
      "2007-09-29 18:23:06+02";1.78
      "2007-09-29 18:25:06+02";1.56
      "2007-09-29 18:27:06+02";1.59
      "2007-09-29 18:29:06+02";1.55
      "2007-09-29 18:31:06+02";1.52
      "2007-09-29 18:33:06+02";1.48
      "2007-09-29 18:35:06+02";1.5
      "2007-09-29 18:37:06+02";1.44
      "2007-09-29 18:39:06+02";1.36
      "2007-09-29 18:41:06+02";1.34
      "2007-09-29 18:43:06+02";1.26
      "2007-09-29 18:45:06+02";1.2
      "2007-09-29 18:47:06+02";1.28
      "2007-09-29 18:49:06+02";1.34
      "2007-09-29 18:51:06+02";1.29
      "2007-09-29 18:53:06+02";1.36
      "2007-09-29 18:55:06+02";1.44
      "2007-09-29 18:57:06+02";1.43
      "2007-09-29 18:59:06+02";1.73
      "2007-09-29 19:01:06+02";1.94
      "2007-09-29 19:03:06+02";1.86
      "2007-09-29 19:05:06+02";1.88
      "2007-09-29 19:07:06+02";1.78
      "2007-09-29 19:09:06+02";1.52
      "2007-09-29 19:11:06+02";1.36
      "2007-09-29 19:13:06+02";1.28
      "2007-09-29 19:15:06+02";1.32
      "2007-09-29 19:17:06+02";1.24
      "2007-09-29 19:19:06+02";1.17
      "2007-09-29 19:21:06+02";1.16
      "2007-09-29 19:23:06+02";1.22
      "2007-09-29 19:25:06+02";1.18
      "2007-09-29 19:27:06+02";1.13
      "2007-09-29 19:29:06+02";1.06
      "2007-09-29 19:31:06+02";1.12
      "2007-09-29 19:33:06+02";1.16
      "2007-09-29 19:35:06+02";1.04
      "2007-09-29 19:37:06+02";0.98
      "2007-09-29 19:39:06+02";0.85
      "2007-09-29 19:41:06+02";0.85
      "2007-09-29 19:43:06+02";1.04
      "2007-09-29 19:45:06+02";0.97
      "2007-09-29 19:47:06+02";1.08
      "2007-09-29 19:49:06+02";1.2
      "2007-09-29 19:51:06+02";0.99
      "2007-09-29 19:53:06+02";0.86
      "2007-09-29 19:55:06+02";0.88
      "2007-09-29 19:57:06+02";0.86
      "2007-09-29 19:59:06+02";0.82
      "2007-09-29 20:01:06+02";0.89
      "2007-09-29 20:03:06+02";0.86
      "2007-09-29 20:05:06+02";0.94
      "2007-09-29 20:07:06+02";0.96
      "2007-09-29 20:09:06+02";1
      "2007-09-29 20:11:06+02";1.11
      "2007-09-29 20:13:06+02";1.06
      "2007-09-29 20:15:06+02";0.94
      "2007-09-29 20:17:06+02";1.18
      "2007-09-29 20:19:06+02";1.2
      "2007-09-29 20:21:06+02";1.05
      "2007-09-29 20:23:06+02";0.94
      "2007-09-29 20:25:06+02";1.02
      "2007-09-29 20:27:06+02";0.96
      "2007-09-29 20:29:06+02";0.85
      "2007-09-29 20:31:06+02";0.79
      "2007-09-29 20:33:06+02";0.92
      "2007-09-29 20:35:06+02";0.7
      "2007-09-29 20:37:06+02";0.78
      "2007-09-29 20:39:06+02";0.64
      "2007-09-29 20:41:06+02";0.54
      "2007-09-29 20:43:06+02";0.68
      "2007-09-29 20:45:06+02";0.58
      "2007-09-29 20:47:06+02";0.48
      "2007-09-29 20:49:06+02";0.46
      "2007-09-29 20:51:06+02";0.4
      "2007-09-29 20:53:06+02";0.5
      "2007-09-29 20:55:06+02";0.4
      "2007-09-29 20:57:06+02";0.49
      "2007-09-29 20:59:06+02";0.38
      "2007-09-29 21:01:06+02";0.32
      "2007-09-29 21:03:06+02";0.31
      "2007-09-29 21:05:06+02";0.22
      "2007-09-29 21:07:05+02";0.2
      "2007-09-29 21:09:05+02";0.17
      "2007-09-29 21:11:05+02";0.12
      "2007-09-29 21:13:05+02";0.22
      "2007-09-29 21:15:05+02";0.15
      "2007-09-29 21:17:05+02";0.18
      "2007-09-29 21:19:05+02";0.09
      "2007-09-29 21:21:05+02";-0.01
      "2007-09-29 21:23:05+02";-0.05
      "2007-09-29 21:25:05+02";0
      "2007-09-29 21:27:05+02";0.12
      "2007-09-29 21:29:05+02";0.09
      "2007-09-29 21:31:05+02";0.18
      "2007-09-29 21:33:05+02";0.04
      "2007-09-29 21:35:05+02";0.02
      "2007-09-29 21:37:05+02";-0.04
      "2007-09-29 21:39:05+02";-0.06
      "2007-09-29 21:41:05+02";0.06
      "2007-09-29 21:43:05+02";0.04
      "2007-09-29 21:45:05+02";0.04
      "2007-09-29 21:47:05+02";0.15
      "2007-09-29 21:49:05+02";0.22
      "2007-09-29 21:51:05+02";0.24
      "2007-09-29 21:53:05+02";0.22
      "2007-09-29 21:55:05+02";0.1
      "2007-09-29 21:57:05+02";0.11
      "2007-09-29 21:59:05+02";0.06
      "2007-09-29 22:01:05+02";0.09
      "2007-09-29 22:03:05+02";0.2
      "2007-09-29 22:05:05+02";0.11
      "2007-09-29 22:07:05+02";0.08
      "2007-09-29 22:09:05+02";0.08
      "2007-09-29 22:11:05+02";0.07
      "2007-09-29 22:13:05+02";0.06
      "2007-09-29 22:15:05+02";0.11
      "2007-09-29 22:17:05+02";0.12
      "2007-09-29 22:19:05+02";0.1
      "2007-09-29 22:21:05+02";0.19
      "2007-09-29 22:23:05+02";0.24
      "2007-09-29 22:25:05+02";0.24
      "2007-09-29 22:27:05+02";0.24
      "2007-09-29 22:29:05+02";0.22
      "2007-09-29 22:31:05+02";0.24
      "2007-09-29 22:33:05+02";0.28
      "2007-09-29 22:35:05+02";0.28
      "2007-09-29 22:37:05+02";0.26
      "2007-09-29 22:39:05+02";0.28
      "2007-09-29 22:41:05+02";0.28
      "2007-09-29 22:43:05+02";0.26
      "2007-09-29 22:45:05+02";0.27
      "2007-09-29 22:47:05+02";0.31
      "2007-09-29 22:49:05+02";0.29
      "2007-09-29 22:51:05+02";0.27
      "2007-09-29 22:53:05+02";0.3
      "2007-09-29 22:55:05+02";0.26
      "2007-09-29 22:57:05+02";0.26
      "2007-09-29 22:59:05+02";0.3
      "2007-09-29 23:01:05+02";0.3
      "2007-09-29 23:03:05+02";0.28
      "2007-09-29 23:05:05+02";0.22
      "2007-09-29 23:07:05+02";0.2
      "2007-09-29 23:09:05+02";0.16
      "2007-09-29 23:11:05+02";0.2
      "2007-09-29 23:13:05+02";0.2
      "2007-09-29 23:15:05+02";0.12
      "2007-09-29 23:17:05+02";0.08
      "2007-09-29 23:19:05+02";0.1
      "2007-09-29 23:21:05+02";0.14
      "2007-09-29 23:23:05+02";0.16
      "2007-09-29 23:25:05+02";0.27
      "2007-09-29 23:27:05+02";0.32
      "2007-09-29 23:29:05+02";0.34
      "2007-09-29 23:31:05+02";0.4
      "2007-09-29 23:33:05+02";0.37
      "2007-09-29 23:35:05+02";0.35
      "2007-09-29 23:37:05+02";0.32
      "2007-09-29 23:39:05+02";0.23
      "2007-09-29 23:41:05+02";0.26
      "2007-09-29 23:43:05+02";0.35
      "2007-09-29 23:45:05+02";0.31
      "2007-09-29 23:47:05+02";0.32
      "2007-09-29 23:49:05+02";0.3
      "2007-09-29 23:51:05+02";0.36
      "2007-09-29 23:53:05+02";0.33
      "2007-09-29 23:55:05+02";0.27
      "2007-09-29 23:57:05+02";0.27
      "2007-09-29 23:59:05+02";0.2
  </code></pre>
  
  <p>Expected results:</p>
  
  <p>Hourly mean for 16 o'clock is : 5.7=5.36+5.80+6.06+5.70+5.58</p>
  
  <pre><code>2007-09-29 16:00  5.7
  </code></pre>
  
  <p>I have tried this code but it doesn't work properly.</p>
  
  <pre><code>select date_trunc('hour', newest_time) as average_time,  
         (oldest_temp + middle_temp + newest_temp) / 3 as average_temp 
  from (  
    select
       date_trunc('hour', dt) as average_time,
       lag(dt, 2) over w as oldest_time,
       lag(dt, 1) over w as middle_time,
       dt as newest_time,
       lag(ambtemp, 2) over w as oldest_temp,
       lag(ambtemp, 1) over w as middle_temp,
       ambtemp as newest_temp   
    from n32   
      window w as (order by dt) 
  ) as s 
  where oldest_time = newest_time - '4 minutes'::interval 
    and middle_time = newest_time - '2 minutes'::interval 
    and extract(minute from newest_time) in (2, 3);
  </code></pre>