coded to categorical variables in a large dataset

An embedded and charset-unspecified text was scrubbed...
Name: not available
Url: https://stat.ethz.ch/pipermail/r-help/attachments/20061229/1ee479fd/attachment.pl
I am working with a dataset where there are 5 possible outcomes (coded 1:5),
I would like to create 5 categorical variables (event1...event5). I am using
a for loop an if statements, but I have a large dataset( approx 100,000
rows) it takes quite a bit of time, is there a way to speed this up? Here is
some sample code of what I am currently doing.
Here is one way you might do it:

X <- sample(1:5, 100, replace=TRUE)

# Your 5 event variables in a matrix
model.matrix(lm(rnorm(length(X)) ~ as.factor(X) - 1))

  Also, along the lines of your approach below, the following using
ifelse() might be better:

event3 <- ifelse(test2 == 3, 1, 0)

  I'm sure other people will post different solutions probably more
elegant than these.
test2 <-rep(seq(1:5),2000)

event1 <- rep(0,nrow(test2))
event2 <- rep(0,nrow(test2))
event3 <- rep(0,nrow(test2))
event4 <- rep(0,nrow(test2))
event5 <- rep(0,nrow(test2))

for(i in 1:length(event1))
{
    if (test2[i]==1)
    {
        event1[i]=1
    }

    if (test2[i]==2)
    {
        event2[i]=1
    }

    if (test2[i]==3)
    {
        event3[i]=1
    }

    if (test2[i]==4)
    {
        event4[i]=1
    }

    if (test2[i]==5)
    {
        event5[i]=1
    }
}

thanks,

Spencer

	[[alternative HTML version deleted]]

______________________________________________
R-help at stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

Chuck Cleland, Ph.D.
NDRI, Inc.
71 West 23rd Street, 8th floor
New York, NY 10010
tel: (212) 845-4495 (Tu, Th)
tel: (732) 512-0171 (M, W, F)
fax: (917) 438-0894
An embedded and charset-unspecified text was scrubbed...
Name: not available
Url: https://stat.ethz.ch/pipermail/r-help/attachments/20061229/b476d7c2/attachment.pl
As Richard has already pointed out you may only need to convert your
numeric vector to a factor but just in case here are a few direct answers:

Using X from Chuck's post here are two ways of creating a 100x5
matrix of indicator variables:

model.matrix(~ X-1, list(X = factor(X)))
outer(X, 1:5, "==")+0

# To create eventi variables
# here is a way of creating them

event1 <- (X == 1) + 0 # and similarly for 2, 3, 4, 5

# or do it in a loop
for(i in 1:5) assign(paste("event", i, sep = ""), (X == i) + 0)

# or create as columns of a data frame
f <- function(i, j) (X == j) + 0
as.data.frame(mapply(f, paste("event", 1:5, sep = ""), 1:5))
I am working with a dataset where there are 5 possible outcomes (coded 1:5),
I would like to create 5 categorical variables (event1...event5). I am using
a for loop an if statements, but I have a large dataset( approx 100,000
rows) it takes quite a bit of time, is there a way to speed this up? Here is
some sample code of what I am currently doing.

test2 <-rep(seq(1:5),2000)

event1 <- rep(0,nrow(test2))
event2 <- rep(0,nrow(test2))
event3 <- rep(0,nrow(test2))
event4 <- rep(0,nrow(test2))
event5 <- rep(0,nrow(test2))

for(i in 1:length(event1))
{
   if (test2[i]==1)
   {
       event1[i]=1
   }

   if (test2[i]==2)
   {
       event2[i]=1
   }

   if (test2[i]==3)
   {
       event3[i]=1
   }

   if (test2[i]==4)
   {
       event4[i]=1
   }

   if (test2[i]==5)
   {
       event5[i]=1
   }
}

thanks,

Spencer

       [[alternative HTML version deleted]]

______________________________________________
R-help at stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

I am working with a dataset where there are 5 possible outcomes (coded 1:5),
I would like to create 5 categorical variables (event1...event5). I am using
a for loop an if statements, but I have a large dataset( approx 100,000
rows) it takes quite a bit of time, is there a way to speed this up? Here is
some sample code of what I am currently doing.

test2 <-rep(seq(1:5),2000)

[...]

As Richard suggested you may not want to do this at all, but ...

If you want these as a matrix, this is fast and direct:

 	mat <- diag(5)[ test2, ]

If not as a matrix

 	event1 <- as.numeric( test2 == 1 )

is concise and

 	for (i in 1:5) assign(paste("event",i,sep=""), as.numeric( test2==i ))

is about as fast as you can get.

HTH,

Chuck

Charles C. Berry                        (858) 534-2098
                                          Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu	         UC San Diego
http://biostat.ucsd.edu/~cberry/         La Jolla, San Diego 92093-0717