maxbre wrote on 09/09/2011 06:28:15 AM:
> 
> 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;


It's not clear to me what the wide format of your example would look like. 
 You start with this:

  SENSOR VALUE          DATE
1      A 270.0  01/01/2010 1
2      B 292.5  01/01/2010 2
3      C   0.0  01/01/2010 3
4      D  45.0  01/01/2010 4
5      E 247.5  01/01/2010 5
6      F 315.0  01/01/2010 6

And you want to change it to ... something like this?

         DATE   A     B  C  D     E   F
 01/01/2010 1 270    NA NA NA    NA  NA
 01/01/2010 2  NA 292.5 NA NA    NA  NA
 01/01/2010 3  NA    NA  0 NA    NA  NA
 01/01/2010 4  NA    NA NA 45    NA  NA
 01/01/2010 5  NA    NA NA NA 247.5  NA
 01/01/2010 6  NA    NA NA NA    NA 315

Jean


> 
> 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
> 
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