[R] Converting column of strings to boolean

[arun]

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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