In a manuscript, I have the following code to illustrate dummy coding of
two factors in a contingency table.
It works, but is surely obscured by the method I used, involving outer()
to find equalities and 0+outer()
to convert to numeric. Can someone help simplify this code to be more
comprehensible and give the
*same* result? I'd prefer a solution that uses base R.
haireye <- margin.table(HairEyeColor, 1:2)
haireye.df <- as.data.frame(haireye)
dummy.hair <- 0+outer(haireye.df$Hair, levels(haireye.df$Hair), `==`)
colnames(dummy.hair) <- paste0('h', 1:4)
dummy.eye <- 0+outer(haireye.df$Eye, levels(haireye.df$Eye), `==`)
colnames(dummy.eye) <- paste0('e', 1:4)
haireye.df <- data.frame(haireye.df, dummy.hair, dummy.eye)
haireye.df
> haireye.df
Hair Eye Freq h1 h2 h3 h4 e1 e2 e3 e4
1 Black Brown 68 1 0 0 0 1 0 0 0
2 Brown Brown 119 0 1 0 0 1 0 0 0
3 Red Brown 26 0 0 1 0 1 0 0 0
4 Blond Brown 7 0 0 0 1 1 0 0 0
5 Black Blue 20 1 0 0 0 0 1 0 0
6 Brown Blue 84 0 1 0 0 0 1 0 0
7 Red Blue 17 0 0 1 0 0 1 0 0
8 Blond Blue 94 0 0 0 1 0 1 0 0
9 Black Hazel 15 1 0 0 0 0 0 1 0
10 Brown Hazel 54 0 1 0 0 0 0 1 0
11 Red Hazel 14 0 0 1 0 0 0 1 0
12 Blond Hazel 10 0 0 0 1 0 0 1 0
13 Black Green 5 1 0 0 0 0 0 0 1
14 Brown Green 29 0 1 0 0 0 0 0 1
15 Red Green 14 0 0 1 0 0 0 0 1
16 Blond Green 16 0 0 0 1 0 0 0 1
>
--
Michael Friendly Email: friendly AT yorku DOT ca
Professor, Psychology Dept. & Chair, Quantitative Methods
York University Voice: 416 736-2100 x66249 Fax: 416 736-5814
4700 Keele Street Web:http://www.datavis.ca
Toronto, ONT M3J 1P3 CANADA
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