[R] allocating factor levels

[David Winsemius]

On Mar 7, 2011, at 10:13 PM, Darcy Webber wrote:

> Dear R users,
>
> I am working on allocating the rows within a dataframe into some
> factor levels.Consider the following dataframe:
>
>               Start.action                  Start.time
> 1            Start.setting    2010-12-30 17:58:00
> 2            Start.setting    2010-12-30 18:40:00
> 3            Start.setting    2010-12-31 22:39:00
> 4            Start.setting    2010-12-31 23:24:00
> 5            Start.setting    2011-01-01 00:30:00
> 6            Start.setting    2011-01-01 01:10:00
> 7            Start.hauling    2011-01-01 07:07:00
> 8            Start.hauling    2011-01-01 14:25:00
> 9            Start.hauling    2011-01-01 21:28:00
> 10          Start.hauling    2011-01-02 03:38:00
> 11          Start.hauling    2011-01-02 09:28:00
> 12          Start.hauling    2011-01-02 14:22:00
> 13          Start.setting    2011-01-02 20:51:00
> 14          Start.setting    2011-01-02 21:33:00
> 15          Start.setting    2011-01-02 22:47:00
> 16          Start.setting    2011-01-02 23:27:00
> 17          Start.setting    2011-01-03 00:35:00
> 18          Start.setting    2011-01-03 01:16:00
> 19          Start.hauling    2011-01-03 04:31:00
> 20          Start.hauling    2011-01-03 08:57:00
>
> I am trying to assign a factor level like the one below (named
> "action") according to the sequence of setting and hauling occuring in
> the "Start.action" column. In fact, it wouldnt even need to be a
> factor or character, it could simply be numbered (i.e., the set/haul
> prefix is useless as I could simply split it afterwards).

  w$action <-  paste(c("set", "haul")[
              1+ c(0, cumsum(w[2:nrow(w), 1] != w[1:(nrow(w)-1), 1])) % 
%2],
              1+ c(0, cumsum(w[2:nrow(w), 1] != w[1:(nrow(w)-1), 1]))  
%/%2 ,
                    sep="")
>
>              Start.action                   Start.time   action
> 1            Start.setting    2010-12-30 17:58:00    set1
> 2            Start.setting    2010-12-30 18:40:00    set1
> 3            Start.setting    2010-12-31 22:39:00    set1
> 4            Start.setting    2010-12-31 23:24:00    set1
> 5            Start.setting    2011-01-01 00:30:00    set1
> 6            Start.setting    2011-01-01 01:10:00    set1
> 7            Start.hauling    2011-01-01 07:07:00   haul1
> 8            Start.hauling    2011-01-01 14:25:00   haul1
> 9            Start.hauling    2011-01-01 21:28:00   haul1
> 10          Start.hauling    2011-01-02 03:38:00   haul1
> 11          Start.hauling    2011-01-02 09:28:00   haul1
> 12          Start.hauling    2011-01-02 14:22:00   haul1
> 13          Start.setting    2011-01-02 20:51:00    set2
> 14          Start.setting    2011-01-02 21:33:00    set2
> 15          Start.setting    2011-01-02 22:47:00    set2
> 16          Start.setting    2011-01-02 23:27:00    set2
> 17          Start.setting    2011-01-03 00:35:00    set2
> 18          Start.setting    2011-01-03 01:16:00    set2
> 19          Start.hauling    2011-01-03 04:31:00   haul2
> 20          Start.hauling    2011-01-03 08:57:00   haul2
>
> It seems like such a simple question, yet I just cant think of how to
> implement this. Any hints or ideas on how I might achieve this would
> be much appreciated.
>
> Regards,
> Darcy
>
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David Winsemius, MD
West Hartford, CT