Converting column of strings to boolean

Hi,

Anther possibility may be to use:

library(MatrixModels)

? model.Matrix(~d-1,sparse=FALSE)
#7 x 4 Matrix of class "ddenseModelMatrix"
?# dblue dgreen dred dyellow
#1 ??? 0????? 0??? 1?????? 0
#2???? 0????? 1??? 0?????? 0
#3???? 0????? 0??? 1?????? 0
#4???? 1????? 0??? 0?????? 0
#5???? 0????? 1??? 0?????? 0
#6???? 0????? 0??? 0?????? 1
#7???? 0????? 0??? 1?????? 0
?model.Matrix(~d-1,sparse=TRUE)
#"dsparseModelMatrix": 7 x 4 sparse Matrix of class "dgCMatrix"
?# dblue dgreen dred dyellow
#1???? .????? .??? 1?????? .
#2???? .????? 1??? .?????? .
#3???? .????? .??? 1?????? .
#4???? 1????? .??? .?????? .
#5???? .????? 1??? .?????? .
#6???? .????? .??? .?????? 1
#7???? .????? .??? 1?????? .
#@ assign:? 1 1 1 1 
#@ contrasts:
#$d
#[1] "contr.treatment"

A.K.


----- Original Message -----
From: Pete Brecknock <Peter.Brecknock at bp.com>
To: r-help at r-project.org
Cc: 
Sent: Saturday, January 26, 2013 6:27 PM
Subject: Re: [R] Converting column of strings to boolean

domcastro wrote

Hi

I'm trying to convert a column of strings (nominal types) to a set of
boolean / binary / logical values. For example, in the column there is
red, blue, green and yellow. There are 100 rows and each has a colour. I
want to convert the column to 4 columns: red, blue, green,yellow and then
either 1 or 0 put in the relevant row.
Thanks

maybe model.matrix will help ....

# d is my understanding of your data
d<-factor(c("red","green","red","blue","green","yellow","red"))
model.matrix(~d -1)

HTH 

Pete



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