[R] reshape not using as id vars what it is supposed to be using?

[Dimitri Liakhovitski]

Thank you, Ista!

you are right - in the paper I was refering to it's "measured" but in
?melt it's measure.vars!

Dimitri

On Tue, Oct 5, 2010 at 12:17 PM, Ista Zahn <izahn at psych.rochester.edu> wrote:
> Hi Dimitri,
> The argument names may have changed. Notice that
>
> melt.data.frame(smiths, measured = c("age", "weight", "height"))
>
> gives a message saying "Using subject as id variables". This is
> because measured variables need to be specified as measure.vars (or an
> abbreviation of that: even m will work because no other arguments
> start with m).
>
>> args(melt.data.frame)
> function (data, id.vars, measure.vars, variable_name = "variable",
>    na.rm = !preserve.na, preserve.na = TRUE, ...)
>
> Bottom line: you need something like
>
> melt.data.frame(smiths, measure.vars = c("age", "weight", "height"))
>
> Best,
> Ista
>
> On Tue, Oct 5, 2010 at 11:36 AM, Dimitri Liakhovitski
> <dimitri.liakhovitski at gmail.com> wrote:
>> Hellow!
>>
>> I am replicating the example givien in "Reshaping Data with the
>> reshape Package" (http://www.jstatsoft.org/v21/i12 - see "download"
>> link on the right), p. 2-3.
>>
>> library(reshape)
>> data(smiths)
>> str(smiths)
>>
>> The text says: "If you specify only one of measured and identifier
>> variables, melt assumes that all the other variables are the OTHER
>> sort:"
>> Hence, the result of the following 5 lines should be identical:
>>
>> melt.data.frame(smiths, id = c("subject", "time"), measured = c("age",
>> "weight","height"))
>> melt.data.frame(smiths, id = c("subject", "time"))
>> melt.data.frame(smiths, id = 1:2)
>> melt.data.frame(smiths, measured = c("age", "weight", "height"))
>> melt.data.frame(smiths)                   # If you do not specify them
>> explicitly, melt will assume that any factor or character variables
>> are id variables
>>
>>
>> However, only the first 3 lines produce the same result.
>> I am especially surprised why line 4 uses "time" as a measured
>> variable, while it should be clear to reshape that "time" is NOT a
>> measured variable?
>>
>>
>> Thank you!
>> --
>> Dimitri Liakhovitski
>> Ninah Consulting
>> www.ninah.com
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> 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.
>>
>
>
>
> --
> Ista Zahn
> Graduate student
> University of Rochester
> Department of Clinical and Social Psychology
> http://yourpsyche.org
>



-- 
Dimitri Liakhovitski
Ninah Consulting
www.ninah.com