[R] how to make automatically each level from data.frame to vector

[Francisco J. Zagmutt]

Looking at the results that you are expecing I think that you just want to 
have only the record from black colored people.  If that't the case, for 
this dataset the easiest way is to subset the data i.e

data(HairEyeColor)
x=as.data.frame(HairEyeColor)
x2=x[x$Hair=="Black",1:3]
x2
    Hair   Eye    Sex
1  Black Brown   Male
5  Black  Blue   Male
9  Black Hazel   Male
13 Black Green   Male
17 Black Brown Female
21 Black  Blue Female
25 Black Hazel Female
29 Black Green Female


Is this what you needed?

Francisco


>From: Muhammad Subianto <subianto at gmail.com>
>To: r-help at stat.math.ethz.ch
>Subject: [R] how to make automatically each level from data.frame to vector
>Date: Sat, 12 Nov 2005 21:37:27 +0100
>
>Dear R-helpers,
>Suppose I have dataset like this below:
>data(HairEyeColor)
>dfHEC <- as.data.frame(as.table(HairEyeColor))
>my.dfHEC <- data.frame(Hair=rep(dfHEC$Hair,dfHEC$Freq),
>                        Eye=rep(dfHEC$Eye,dfHEC$Freq),
>                        Sex=rep(dfHEC$Sex,dfHEC$Freq))
>my.dfHEC
>my.dfHEC$Hair
>my.dfHEC$Eye
>my.dfHEC$Sex
>

>and I know all levels for Hair, Eye and Sex.
>In my case, I want to "expand.grid" all attributes but in Hair I only
>include "Black" hair:
>
>Hair.e <- c("Black")
>Eye.e <- c("Brown","Blue","Hazel","Green")
>Sex.e <- c("Male","Female")
>
>#I can do like,
>dfHEC.Black <- expand.grid(Hair.e,Eye.e,Sex.e)
>dfHEC.Black
>
>My question is how to make automatically each level from data.frame to 
>vector.
>I don't want to make definition for each level again (Hair.e, Eye.e, 
>Sex.e).
>In the others word, how can I make "expand.grid" (each level) from
>data.frame automatically if Hair is only ("Black").
>The result I need like,
>
>    Var1  Var2   Var3
>1 Black Brown   Male
>2 Black  Blue   Male
>3 Black Hazel   Male
>4 Black Green   Male
>5 Black Brown Female
>6 Black  Blue Female
>7 Black Hazel Female
>8 Black Green Female
>
>Thanks in advance.
>Best, Muhammad Subianto
>
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