[R] reshape() to wide with varying number of responses to fields

[hadley wickham]

Hi Jon,

You can do this with the reshape package.  Your data are already in
"molten" form, so you can just do:

cast(rename(df, c("Value" = "value"), PID ~ Field)

You can find out more about reshape at http://had.co.nz/reshape

Hadley

On 9/22/07, Jon Minton <jm540 at york.ac.uk> wrote:
> Hello,
>
> I have a dataframe containing the following variables:
>
>         PID, Field, Value
>
> Where PID refers to a unique individual, Field to a particular question, and
> Value to a particular response to a question.
>
> I'd like this in wide format, with a different row for each PID.
> However.... there are differing numbers of Values associated with each
> Field, for each PID.
> For example, a Field question may be "Which of the following are important
> for you:" – some people tick one box in response to it, other 3 or 4: thus
> PID A might generate 3 Values for Field X, whereas PID B would only generate
> 1 Value:
>
> PID     Field Value
> A       X       a
> A       X       b
> A       X       c
> B       X       b
> Etc.
> What I'd like is a wide format, with one Pid per row, and enough columns for
> each of the possible values the PID could provide for a particular field,
> filled in with the values if they exist, or NAs if they don't:
>
> PID     X.1     X.2     X.3
> A       a       b       c
> B       b       NA      NA
> Etc.
>
> I already know the maximum number of Values any PID has provided for each
> Field (i.e. the maximum number of columns to allow for each Field response),
> but don't know how to create this dataframe using reshape (or if reshape is
> the right function to use).
>
>
> Any help much appreciated. I've not seen a 'how-to' regarding this in the
> archive.
> Thanks, Jon
>
>
>
>
> Checked by AVG Free Edition.
>
> 20/09/2007
> 12:07
>
>
> ______________________________________________
> 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.
>


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