The aggregate function ts.last() returns the newest value, determined by timecode, for each group.
In the event of a tie, such as simultaneous timecode values for a particular group, all tied results are returned. If a sequence number is present with the data, it can break a tie, assuming it is unique across identical timecode values.
ts.last() uses the argument "value.expression" to specify the column for which newest value of the group is to be returned.
- This function is valid only on columns with numeric types.
- Nulls are not included in the result computation.
Example 1: Get the newest value of the 'temperature' column of sequenced PTI table
- Get the newest value.
> df_seq_last <- df_seq_grp %>% summarise(last_temp = ts.last(temperature))
- Print the results.
> df_seq_last %>% arrange(TIMECODE_RANGE, buoyid, last_temp) # Source: lazy query [?? x 4] # Database: [Teradata 16.20.50.01] [Teradata Native Driver 17.0.0.2] # [TDAPUSER@<hostname>/TDAPUSERDB] # Ordered by: TIMECODE_RANGE, buoyid, last_temp TIMECODE_RANGE `GROUP BY TIME(MINUTES(~ buoyid last_temp <chr> <int64> <int> <int> 1 2014-01-06 08:00:00.000000+00:00,2014-01-06 08:3~ 35345 0 100 2 2014-01-06 09:00:00.000000+00:00,2014-01-06 09:3~ 35347 1 79 3 2014-01-06 10:00:00.000000+00:00,2014-01-06 10:3~ 35349 44 43 4 2014-01-06 10:30:00.000000+00:00,2014-01-06 11:0~ 35350 22 23 5 2014-01-06 10:30:00.000000+00:00,2014-01-06 11:0~ 35350 44 43 6 2014-01-06 21:00:00.000000+00:00,2014-01-06 21:3~ 35371 2 82
Example 2: Get the newest value of the 'temperature' column of non-PTI table
- Get the newest value.
> df_nonpti_last <- df_nonpti_grp %>% summarise(last_temp = ts.last(temperature))
- Print the results.
> df_nonpti_last %>% arrange(TIMECODE_RANGE, last_temp) # Source: lazy query [?? x 3] # Database: [Teradata 16.20.50.01] [Teradata Native Driver 17.0.0.2] # [TDAPUSER@<hostname>/TDAPUSERDB] # Ordered by: TIMECODE_RANGE, last_temp TIMECODE_RANGE `GROUP BY TIME(MINUTES(~ last_temp <chr> <int64> <int> 1 2014-01-06 08:00:00.000000+00:00,2014-01-06 08:01:00.0~ 23149921 10 2 2014-01-06 08:01:00.000000+00:00,2014-01-06 08:02:00.0~ 23149922 10 3 2014-01-06 08:02:00.000000+00:00,2014-01-06 08:03:00.0~ 23149923 10 4 2014-01-06 08:03:00.000000+00:00,2014-01-06 08:04:00.0~ 23149924 10 5 2014-01-06 08:04:00.000000+00:00,2014-01-06 08:05:00.0~ 23149925 10 6 2014-01-06 08:05:00.000000+00:00,2014-01-06 08:06:00.0~ 23149926 10 7 2014-01-06 08:06:00.000000+00:00,2014-01-06 08:07:00.0~ 23149927 10 8 2014-01-06 08:07:00.000000+00:00,2014-01-06 08:08:00.0~ 23149928 10 9 2014-01-06 08:08:00.000000+00:00,2014-01-06 08:09:00.0~ 23149929 NA 10 2014-01-06 08:09:00.000000+00:00,2014-01-06 08:10:00.0~ 23149930 99 # ... with more rows