Hi,
May bet this also helps:
set.seed(12345)
x <- c(1:30)
x1 <- sample(x, 15, replace = TRUE)
x2 <- sample(x, 15, replace = TRUE)
x3 <- sample(x, 15, replace = TRUE)
x4 <- sample(x, 15, replace = TRUE)
indx<-1+2*(x1==1)+4*(x2==1)+8*(x3==1)+16*(x4==1)
as.numeric(indx!=1)
#[1] 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0
#Speed comparisons
set.seed(1235)
x <- c(1:1e7)
x1 <- sample(x, 1e7, replace = TRUE)
x2 <- sample(x, 1e7, replace = TRUE)
x3 <- sample(x, 1e7, replace = TRUE)
x4 <- sample(x, 1e7, replace = TRUE)
system.time(res1 <-ifelse(x1 == 1 | x2 == 1 | x3 == 1 | x4 == 1, 1, 0))
# user system elapsed
# 3.740 0.256 4.003
system.time(res2<-as.numeric(x1 == 1 | x2 == 1 | x3 == 1 | x4 == 1))
# user system elapsed
# 0.996 0.076 1.077
system.time({indx<-1+2*(x1==1)+4*(x2==1)+8*(x3==1)+16*(x4==1)
res3<-as.numeric(indx!=1)})
# user system elapsed
# 0.596 0.240 0.840
system.time(res4<-rowSums(cbind(x1, x2, x3, x4) == 1))
# user system elapsed
# 0.732 0.192 0.926
system.time(res4New<-sign(rowSums(cbind(x1, x2, x3, x4) == 1)))
# user system elapsed
# 0.824 0.232 1.062
X <- cbind(x1, x2, x3, x4)
system.time({
res5<-as.integer(apply(X, 1, function(x) any(x == 1L)))})
# user system elapsed
#113.308 0.208 113.729
system.time(res6<-apply(X, 1, function(x) if (any(x == 1L)) 1 else 0))
#user system elapsed
# 61.660 0.216 61.989
identical(res1,res6)
#[1] TRUE
identical(res1,res2)
#[1] TRUE
identical(res1,res3)
#[1] TRUE
identical(res1,res4)
#[1] TRUE
identical(res1,res4New)
#[1] TRUE
A.K.
----- Original Message -----
From: Brian Perron <beper...@umich.edu>
To: r-help@r-project.org
Cc:
Sent: Wednesday, June 19, 2013 9:24 AM
Subject: [R] alternative to ifelse
Greetings:
I am looking for a way to avoid using the ifelse function for
constructing a new variable. More specifically, assume I have a set
of variables with scores ranging from 1 to 30.
set.seed(12345)
x <- c(1:30)
x1 <- sample(x, 15, replace = TRUE)
x2 <- sample(x, 15, replace = TRUE)
x3 <- sample(x, 15, replace = TRUE)
x4 <- sample(x, 15, replace = TRUE)
I want to construct a dichotomous variable that tests whether any of
the variables contains the value 1.
newVar <-ifelse(x1 == 1 | x2 == 1 | x3 == 1 | x4 == 1, 1, 0)
I want to avoid the ifelse function because I have a number of large
variable lists that will require new variables to be created. I'm
sure there is a simple way to do this, but I haven't had any luck with
my search!
Thanks in advance.
Brian
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______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
