[R] Reshaping data with xtabs giving me 'extra' data

[Henrique Dallazuanna]

Try with tapply:

 with(do.call(rbind, df.list), tapply(Score, list(Date, Time, Show), length))

On Wed, Jan 20, 2010 at 10:20 AM, Tony B <tony.breyal at googlemail.com> wrote:
> Dear all,
>
> Lets say I have several data frames as follows:
>
>> set.seed(42)
>> dates <- as.Date(c("2010-01-19", "2010-01-20"))
>> times <- c("09:30:00", "11:30:00", "13:30:00", "15:30:00")
>> shows <- c("Red Dwarf", "Being Human", "Doctor Who")
>>
>> df1 <- data.frame(Date = dates[1], Time = times[1], Show = shows, Score = 1:3)
>> df2 <- data.frame(Date = dates[1], Time = times[2], Show = shows, Score = 1:3)
>> df3 <- data.frame(Date = dates[1], Time = times[4], Show = shows, Score = 1:3)
>> df4 <- data.frame(Date = dates[2], Time = times[1], Show = shows, Score = 1:3)
>> df5 <- data.frame(Date = dates[2], Time = times[2], Show = shows, Score = 1:3)
>> df6 <- data.frame(Date = dates[2], Time = times[3], Show = shows, Score = 1:3)
>> df7 <- data.frame(Date = dates[2], Time = times[4], Show = shows, Score = 1:3)
>> df7
>        Date     Time        Show Score
> 1 2010-01-20 15:30:00   Red Dwarf     1
> 2 2010-01-20 15:30:00 Being Human     2
> 3 2010-01-20 15:30:00  Doctor Who     3
>
> I would like to somehow reshape the data into a different format:
>
>> df.list <- list(df1, df2, df3, df4, df5, df6, df7)
>> my.df <- Reduce(function(x, y) merge(x, y, all=TRUE), df.list, accumulate=F)
>> my.xtab <- xtabs(as.numeric(Score) ~ Date + Show + Time, data = my.df)
>
> This is where my problem occurs. In Time = 13:30:00, there is now data
> for "2010-01-19" which was not in any of my original data frames
> above:
>
>> # I do not want the zeros below
>> my.xtab[,,"13:30:00"]
>            Show
> Date         Being Human Doctor Who Red Dwarf
>  2010-01-19           0          0         0
>  2010-01-20           2          3         1
>
> Perhaps I am missing something in the way i call the xtabs function?
>
> Thank you kindly for your time,
> Tony Breyal
>
> OS: Windows XP 64bit
>> sessionInfo()
> R version 2.10.0 (2009-10-26)
> i386-pc-mingw32
>
> locale:
> [1] LC_COLLATE=English_United States.1252  LC_CTYPE=English_United
> States.1252    LC_MONETARY=English_United States.1252
> LC_NUMERIC=C                           LC_TIME=English_United States.
> 1252
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods
> base
>
> loaded via a namespace (and not attached):
> [1] tools_2.10.0
>
> ______________________________________________
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> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>



-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O