R help - May 2008 - Transform values from one column into column names of new dataframe

Hi, I have a question about reformatting data. It looks like it should
be simple, but I've been working at it for awhile now and it's about
time I ask for help.

My data look like this:

ITEM VALUE STEP
item1 A          first
item2 C          first
item2 D          second
item1 A          second
item3 A          first
item3 B          second
item3 A          third

I just want to transform it so they look like this:

ITEM FIRST SECOND THIRD
item1 A         A                NA
item2 C         D                NA
item3 A         B                A

Basically taking the values of the "STEP" column and using those as
the column names and merging together the items.

I appreciate your help,
-Matt

On Fri, May 2, 2008 at 11:05 AM, Matt <mvgnyc at gmail.com>
wrote:
> Hi, I have a question about reformatting data. It looks like it should
>  be simple, but I've been working at it for awhile now and it's
about
>  time I ask for help.
>
>  My data look like this:
>
>  ITEM VALUE STEP
>  item1 A          first
>  item2 C          first
>  item2 D          second
>  item1 A          second
>  item3 A          first
>  item3 B          second
>  item3 A          third
>
>  I just want to transform it so they look like this:
>
>  ITEM FIRST SECOND THIRD
>  item1 A         A                NA
>  item2 C         D                NA
>  item3 A         B                A
>
>  Basically taking the values of the "STEP" column and using those
as
>  the column names and merging together the items.
Have a look at the reshape package (http://had.co.nz/reshape):

install.packages("reshape")
library(reshape)

names(mydf) <- tolower(names(mydf))
cast(mydf, item ~ step, length)
cast(mydf, item ~ step, function(x) x[1])

Hadley

-- 
http://had.co.nz/

Try this also:

noquote(with(x, tapply(VALUE, list(ITEM, STEP), paste)))

On Fri, May 2, 2008 at 1:05 PM, Matt <mvgnyc@gmail.com> wrote:
> Hi, I have a question about reformatting data. It looks like it should
> be simple, but I've been working at it for awhile now and it's
about
> time I ask for help.
>
> My data look like this:
>
> ITEM VALUE STEP
> item1 A          first
> item2 C          first
> item2 D          second
> item1 A          second
> item3 A          first
> item3 B          second
> item3 A          third
>
> I just want to transform it so they look like this:
>
> ITEM FIRST SECOND THIRD
> item1 A         A                NA
> item2 C         D                NA
> item3 A         B                A
>
> Basically taking the values of the "STEP" column and using those
as
> the column names and merging together the items.
>
> I appreciate your help,
> -Matt
>
> ______________________________________________
> R-help@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.
>


-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

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