Hi:
There are two ways to go about this, depending on what you want.
# 1: Jean's output format:
# I'm using the reshape package here with cast(),
# but it should work similarly with dcast() in reshape2:
> cast(example, DATE ~ SENSOR, value = 'VALUE')
DATE A B C D E F
1 01/01/2010 1 270 NA NA NA NA NA
2 01/01/2010 2 NA 292.5 NA NA NA NA
3 01/01/2010 3 NA NA 0 NA NA NA
4 01/01/2010 4 NA NA NA 45 NA NA
5 01/01/2010 5 NA NA NA NA 247.5 NA
6 01/01/2010 6 NA NA NA NA NA 315
# Method 2: One line per day - requires redefinition of date
example$date <- as.Date('01/01/2010', format = '%m/%d/%Y')
cast(example, date ~ SENSOR, value = 'VALUE')
date A B C D E F
1 2010-01-01 270 292.5 0 45 247.5 315
In both cases, note the use of value = 'VALUE' in the cast() call. It
needs value_var = 'VALUE' instead of value = 'VALUE' if you're using
dcast() from reshape2 instead:
library('reshape2')
dcast(example, DATE ~ SENSOR, value_var = 'VALUE')
dcast(example, date ~ SENSOR, value_var = 'VALUE')
HTH,
Dennis
On Fri, Sep 9, 2011 at 4:28 AM, maxbre <mbres...@arpa.veneto.it> wrote:
> This is my reproducible example:
>
> example<-structure(list(SENSOR = structure(1:6, .Label = c("A", "B", "C",
> "D", "E", "F"), class = "factor"), VALUE = c(270, 292.5, 0, 45,
> 247.5, 315), DATE = structure(1:6, .Label = c(" 01/01/2010 1",
> " 01/01/2010 2", " 01/01/2010 3", " 01/01/2010 4", " 01/01/2010 5",
> " 01/01/2010 6"), class = "factor")), .Names = c("SENSOR", "VALUE",
> "DATE"), class = "data.frame", row.names = c("1", "2", "3", "4",
> "5", "6"))
>
> I need to resahpe "example" in a wide format so that “SENSOR” appear as
> columns and “DATE” as rows with corresponding “VALUE” as value;
>
> I thought it was very simple so that I’ve been trying this:
>
> dcast(example,DATE~SENSOR)
>
> But I've got this message:
>
> Using DATE as value column. Use the value argument to cast to override this
> choice
> Errore in `[.data.frame`(data, , variables, drop = FALSE) :
> undefined columns selected
>
> and even if by using the value argument sorted out any good result…
>
> sorry for the very trivial question, I've been looking at documentation and
> forums anywhere but I was not successful at all and now I’m somehow in the
> right middle of nowhere…
>
> any help or hint for this?
>
> thank you
>
> max
>
> --
> View this message in context:
> http://r.789695.n4.nabble.com/reshape-data-from-long-to-wide-format-tp3801381p3801381.html
> Sent from the R help mailing list archive at Nabble.com.
>
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