To transform a vector of qualitatives values into a dataframe of quantitatives values

Hi

 From the vector
X <- c(A, A, B, C, B, A, C)

I would like to build the Dataframe :
data.frame( A=c(1,1,0,0,0,1,0), B=c(0,0,1,0,1,0,0), C=c(0,0,0,1,0,0,1))

Any ideas ?
Michel ARNAUD
Charg? de mission aupr?s du DRH
DGDRD-Drh - TA 174/04
Av Agropolis 34398 Montpellier cedex 5
tel : 04.67.61.75.38
fax : 04.67.61.57.87
port: 06.47.43.55.31
Hi
-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
project.org] On Behalf Of Arnaud Michel
Sent: Wednesday, December 11, 2013 2:01 PM
To: R help
Subject: [R] To transform a vector of qualitatives values into a
dataframe of quantitatives values

Hi

 From the vector
X <- c(A, A, B, C, B, A, C)
What is A, B and C? If you expect them to be letters, they need to be in parentheses.
I would like to build the Dataframe :
data.frame( A=c(1,1,0,0,0,1,0), B=c(0,0,1,0,1,0,0), C=c(0,0,0,1,0,0,1))

Any ideas ?
X <- sample(letters[1:3], 10, replace=T)
X
 [1] "c" "c" "a" "b" "c" "c" "a" "a" "a" "a"
data.frame(A=(X=="a"), B=(X=="b"), C=(X=="c"))

Petr

--
Michel ARNAUD
Charg? de mission aupr?s du DRH
DGDRD-Drh - TA 174/04
Av Agropolis 34398 Montpellier cedex 5
tel : 04.67.61.75.38
fax : 04.67.61.57.87
port: 06.47.43.55.31

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Hi

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
project.org] On Behalf Of Arnaud Michel
Sent: Wednesday, December 11, 2013 2:01 PM
To: R help
Subject: [R] To transform a vector of qualitatives values into a
dataframe of quantitatives values

Hi

  From the vector
X <- c(A, A, B, C, B, A, C)
What is A, B and C? If you expect them to be letters, they need to be in parentheses.
You mean "quotes", not parentheses.

I would like to build the Dataframe :
data.frame( A=c(1,1,0,0,0,1,0), B=c(0,0,1,0,1,0,0), C=c(0,0,0,1,0,0,1))

Any ideas ?
X <- sample(letters[1:3], 10, replace=T)
X
  [1] "c" "c" "a" "b" "c" "c" "a" "a" "a" "a"
data.frame(A=(X=="a"), B=(X=="b"), C=(X=="c"))
A simpler way is to use model.matrix.  With your example,

X <- factor(X)
m <- model.matrix( ~ X - 1)

(The names of the columns may need adjusting.)

Duncan Murdoch
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