[R] transform key value pair to column

[Wacek Kusnierczyk]

see ?stack, for example.

vQ

Tan, Richard wrote:
> Hi, is there a good way (instead of a time-consuming for loop) to
> transfer a key/value pair dataframe to a dataframe with key as column
> and value as row?  For example, I have a dataframe with three columns:
> id, code, value:
>  
> id,code,value
> 1,hi,10.3
> 1,lo,5.2
> 2,hi,19.4
> 3,hi,20
> 3,lo,12
> 4,lo,5.8
>  
> I want to get a dataframe like this:
>  
> id,hi,lo
> 1,10.3,5.2
> 2,19.4,NA
> 3,20,12
> 4,NA,5.8
>  
> Thank you,
> Richard
>
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