[R] turning comma separated string from multiple choices into flags

[Henrique Dallazuanna]

Try this:

table(rep(x$age, unlist(lapply(strsplit(x$favorite_magazine, ","), length))),
        unlist(strsplit(x$favorite_magazine, ",")))

On Mon, Sep 29, 2008 at 11:45 AM, June Kim <juneaftn at gmail.com> wrote:
> Hello,
>
> I use google docs' Forms to conduct surveys online. Multiple choices
> questions are coded as comma separated values.
>
> For example,
>
> if the question is like:
>
> 1. What magazines do you currently subscribe to? (you can choose
> multiple choices)
> 1) Fast Company
> 2) Havard Business Review
> 3) Business Week
> 4) The Economist
>
> And if the subject chose 1) and 3), the data is coded as a cell in a
> spreadsheet as,
>
> "Fast Company, Business Week"
>
> I read the data with read.csv into R. To analyze the data, I have to
> change that string into something like flags(indicator variables?).
> That is, there should be 4 variables, of which values are either 1 or
> 0, indicating chosen or not-chosen respectively.
>
> Suppose the data is something like,
>
>> survey1
>  age                                    favorite_magazine
> 1  29                                         Fast Company
> 2  31                          Fast Company, Business Week
> 3  32 Havard Business Review, Business Week, The Economist
>>
>
> Then I have to chop the string in favorite_magazine column to turn
> that data into something like,
>
>> survey1transformed
>  age Fast Company Havard Business Review Business Week The Economist
> 1  29            1                      0             0             0
> 2  31            1                      0             1             0
> 3  32            0                      1             1             1
>>
>
> Actually I have many more multiple choice questions in the survey.
>
> What is the easy elegant and natural way in R to do the job?
>
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>



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