[R] Simple reshape problem I am completely missing

[Ista Zahn]

The data is already in a "long" form, it doesn't require melting. The
problem was simply that you used the wrong argument name: change
"value.vars" to "value.var", i.e.,

dcast(md2,  group ~ tps , value.var  = "sum")

should work fine.

Best,
Ista

On Tue, Jul 24, 2012 at 1:23 PM, jose Bartolomei <surfprjab at hotmail.com> wrote:
>
> Did you melt first?
>
> library(reshape2)
> ?melt
>
>> Date: Tue, 24 Jul 2012 09:17:08 -0800
>> From: jrkrideau at inbox.com
>> To: r-help at r-project.org
>> Subject: [R] Simple reshape problem I am completely missing
>>
>> I seem to be doing something really stupid or missing something really obvious  but what?
>>
>> I have a simple three column data.frame that I would like to reshape to wide preferably using reshape2.
>>
>> An example from http://stackoverflow.com/questions/9617348/reshape-three-column-data-frame-to-matrix looked perfect except I wanted a data frame but it seemed okay. I just changed acast to dcast and it seems fine.
>>
>> Stackoverflow example:
>> tmp <- data.frame(x=gl(2,3, labels=letters[24:25]),
>>                   y=gl(3,1,6, labels=letters[1:3]),
>>                   z=c(1,2,3,3,3,2))
>> dd  <-  dcast(tmp, x~y, value.var="z")
>>
>> My Example: Does NOT work
>>
>> md2  <-  structure(list(group = structure(c(1L, 1L, 1L, 2L, 2L, 3L, 3L,
>> 4L, 4L, 4L, 5L, 5L, 6L, 6L, 7L, 7L, 7L, 8L, 8L), .Label = c("X1",
>> "X2", "X3", "X4", "X5", "X6", "X7", "X8"), class = "factor"),
>>     tps = structure(c(7L, 12L, 14L, 4L, 8L, 9L, 16L, 6L, 7L,
>>     11L, 6L, 15L, 10L, 13L, 3L, 4L, 5L, 1L, 2L), .Label = c("A",
>>     "C", "D", "E", "G", "I", "L", "M", "N", "P", "Q", "R", "S",
>>     "T", "V", "Y"), class = "factor"), sum = c(0.914913196595112,
>>     0.0367565080432513, 0.0483302953616366, 0.982727803634948,
>>     0.0172721963650521, 0.0483302953616366, 0.951669704638363,
>>     0.89764100023006, 0.0850868034048879, 0.0172721963650521,
>>     0.951669704638363, 0.0483302953616366, 0.963243491956749,
>>     0.0367565080432513, 0.89764100023006, 0.0540287044083034,
>>     0.0483302953616366, 0.982727803634948, 0.0172721963650521
>>     )), .Names = c("group", "tps", "sum"), row.names = c(NA,
>> -19L), class = "data.frame")
>>
>> dcast(md2,  group ~ tps , value.vars  = "sum")
>>
>>
>> What am I doing wrong?
>>
>> John Kane
>> Kingston ON Canada
>>
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