[R] turning comma separated string from multiple choices into flags
juneaftn at gmail.com
Mon Sep 29 16:45:46 CEST 2008
I use google docs' Forms to conduct surveys online. Multiple choices
questions are coded as comma separated values.
if the question is like:
1. What magazines do you currently subscribe to? (you can choose
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
"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,
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,
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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