Thanks for the prompt reply, Dr. Winsemius.
reshape(FullLong)
Will return the original data frame, but that wasn't quite what I wanted. I
wanted to take it to a wider form than the original.
But I just answered my own question (typically, _after_ asking the world at
large).
FullWide <- reshape(Raw,
v.names=c("base.score", "score.90d"),
timevar="instrument",
idvar=c("site", "id"),
direction="wide")
gives me what I was looking for. I suspect there isn't a way to go directly
from FullLong to FullWide, but if someone can prove me wrong, I'd love to see
how.
Benjamin Nutter | Biostatistician | Quantitative Health Sciences
Cleveland Clinic | 9500 Euclid Ave. | Cleveland, OH 44195 | (216)
445-1365
-----Original Message-----
From: David Winsemius [mailto:dwinsem...@comcast.net]
Sent: Wednesday, October 17, 2012 5:18 PM
To: Nutter, Benjamin
Cc: r-help@r-project.org
Subject: Re: [R] Comparing dcast and reshape
On Oct 17, 2012, at 2:09 PM, Nutter, Benjamin wrote:
> I'm in the middle of my own little intellectual exercise comparing
> dcast() and reshape() and have successfully stumped myself. I want to
> melt() a data frame, then dcast() it into a new form. After doing so,
> I want to duplicate the process using reshape().
>
> So far, I can do the melt and cast
>
> require(reshape2)
>
> Raw <- data.frame(site = c(1, 1, 1, 1, 2, 2, 2, 2),
> id = c(1, 1, 2, 2, 1, 1, 2, 2),
> instrument = rep(c("beck", "phq"), 4),
> base.score = c(27, 13, 31, 11, 22, 10, 41, 17),
> score.90d = c(20, 11, 27, 12, 24, 8, 34, 15))
>
> Full.Melt <- melt(Raw, id.vars=c("site", "id", "instrument"),
> measure.vars=c("base.score", "score.90d"))
>
> FullCast <- dcast(Full.Melt, site + id ~ instrument + variable,
> value.var="value")
>
>> FullCast
> site id beck_base.score beck_score.90d phq_base.score phq_score.90d
> 1 1 1 27 20 13 11
> 2 1 2 31 27 11 12
> 3 2 1 22 24 10 8
> 4 2 2 41 34 17 15
>
>
> I can also replicate the melt using reshape, but I can't reshape it
> into the same wide format.
>
> FullLong <- reshape(Raw,
> varying=list(score=c("base.score", "score.90d")),
> idvar=c("site", "id", "instrument"),
> direction="long")
>
>
> Any pointers on how to get FullLong into the same wide format as
> FullCast?
The reshape function will "recognize" that the object was created as a
wide->long reshaping and if you just use this code, you will get back
the original:
reshape(FullLong)
--
David Winsemius, MD
Alameda, CA, USA
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