[R] reshaping column items into rows per unique ID

[peter dalgaard]

It depends quite strongly on what you want to do with the result, but I wonder if what is really needed might be a list of diettypes per person, i.e. continuing from Eric's code

> On 25 Feb 2018, at 18:56 , Eric Berger <ericjberger at gmail.com> wrote:
> 
> Hi Allaisone,
> I took a slightly different approach but you might find this either as or
> more useful than your approach, or at least a start on the path to a
> solution you need.
> 
> df1   <-
> data.frame(CustId=c(1,1,1,2,3,3,4,4,4),DietType=c("a","c","b","f","a","j","c","c","f"),
>                    stringsAsFactors=FALSE)

> with(df1, tapply(DietType, CustId, list))
$`1`
[1] "a" "c" "b"

$`2`
[1] "f"

$`3`
[1] "a" "j"

$`4`
[1] "c" "c" "f"

or maybe get rid of duplicates with

> with(df1, tapply(DietType, CustId, unique))
$`1`
[1] "a" "c" "b"

$`2`
[1] "f"

$`3`
[1] "a" "j"

$`4`
[1] "c" "f"



-- 
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
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