I have a question that must have a simple answer (but eludes me).
I need a row-by-row logical comparison across three numeric variables
in
a data frame: foo$x, foo$y, foo$z. The logic is
if( x < y || x > z ) 1 else 0
for a particular row.
It is simple and very inefficient to use for(i in 1:length(foo$x)){ }
loops. How can I accomplish this using sappy( ) / lapply( ) / apply( )
or some other more efficient method?
Thank you in advance,
Greg
Greg Tarpinian wrote:> I have a question that must have a simple answer (but eludes me). > I need a row-by-row logical comparison across three numeric variables > in > a data frame: foo$x, foo$y, foo$z. The logic is > > if( x < y || x > z ) 1 else 0 > > for a particular row. > > It is simple and very inefficient to use for(i in 1:length(foo$x)){ } > loops. How can I accomplish this using sappy( ) / lapply( ) / apply( ) > or some other more efficient method?X <- as.data.frame(matrix(rnorm(30), ncol=3)) X V1 V2 V3 1 -0.48026236 0.8629789 -1.2600858 2 -1.32408219 -0.5590268 1.1310638 3 0.02717575 -0.5661402 0.7824019 4 0.80783373 0.2300440 -0.4477275 5 1.24518907 -0.3778392 1.7546530 6 -0.39254125 -1.0388962 -0.4436296 7 -1.44473455 1.8606963 0.4253889 8 -0.63543047 -1.6408418 -1.0409473 9 0.81075970 0.3914066 -1.0361739 10 1.66021280 -1.6694101 -0.4810839 with(X, ifelse(V1 < V2 | V1 > V3, 1, 0)) [1] 1 1 0 1 0 1 1 1 1 1> Thank you in advance, > > Greg > > ______________________________________________ > 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
You don't need apply. Just do foo$result <- ifelse((foo$x < foo$y) | (foo$x > foo$z), 1, 0) On 5/10/07, Greg Tarpinian <sasprog474 at yahoo.com> wrote:> I have a question that must have a simple answer (but eludes me). > I need a row-by-row logical comparison across three numeric variables > in > a data frame: foo$x, foo$y, foo$z. The logic is > > if( x < y || x > z ) 1 else 0 > > for a particular row. > > It is simple and very inefficient to use for(i in 1:length(foo$x)){ } > loops. How can I accomplish this using sappy( ) / lapply( ) / apply( ) > or some other more efficient method? > > Thank you in advance, > > Greg > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >-- Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem you are trying to solve?
ifelse(((x < y) | (x > z)), 1, 0) Note in particular the use of | instead of || for elementwise comparisons. Petr Greg Tarpinian napsal(a):> I have a question that must have a simple answer (but eludes me). > I need a row-by-row logical comparison across three numeric variables > in > a data frame: foo$x, foo$y, foo$z. The logic is > > if( x < y || x > z ) 1 else 0 > > for a particular row. > > It is simple and very inefficient to use for(i in 1:length(foo$x)){ } > loops. How can I accomplish this using sappy( ) / lapply( ) / apply( ) > or some other more efficient method? > > Thank you in advance, > > Greg > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >-- Petr Klasterecky Dept. of Probability and Statistics Charles University in Prague Czech Republic
Thank you all for your answers... To summarize,
1. with(X, ifelse(V1 < V2 | V1 > V3, 1, 0))
2. ifelse((foo$x < foo$y) | (foo$x > foo$z), 1, 0)
3. with(foo, (x < y) * (x > z))
were the responses to my question (see below).
Kindly,
Greg
----------- Original post -----------> I have a question that must have a simple answer (but eludes me).
> I need a row-by-row logical comparison across three numeric variables
> in a data frame: foo$x, foo$y, foo$z. The logic is
>
> if( x < y || x > z ) 1 else 0
>
> for a particular row.
>
> It is simple and very inefficient to use for(i in 1:length(foo$x)){ }
> loops. How can I accomplish this using sappy( ) / lapply( ) /
> apply( ) or some other more efficient method?
>
> Thank you in advance,
>
> Greg