Hi Chuck, thank you *very* much! That really helped! b On 9 March 2012 17:15, <cbe...@tajo.ucsd.edu> wrote: > Benilton Carvalho <beniltoncarva...@gmail.com> writes: > >> Hi, >> >> what is the proper of of "passing a missing value" so I can extract >> the entire i-th row of a matrix (in a list of lists) without >> pre-computing the number of cols? >> >> For example, if I know that the matrices have 2 columns, I can do the >> following: >> >> set.seed(1) >> x0 <- lapply(1:10, function(i) replicate(4, list(matrix(rnorm(10), nc=2)))) >> lapply(lapply(x0, '[[', 3), '[', i=2, j=1:2) >> >> (given that if I don't specify j, I only get the first element) >> >> but if the number of columns are variable: >> >> x1 <- lapply(1:10, function(i) replicate(4, list(matrix(rnorm(100), >> nc=sample(c(2, 4, 5, 10), 1))))) >> >> what would be the value of J below? >> >> lapply(lapply(x1, '[[', 3), '[', i=2, j=J) >> > > > I think you want 'j=TRUE'. Note: > > all.equal( > lapply(lapply(x0, '[[', 3), '[', i=2,j=TRUE), > lapply(lapply(x0, '[[', 3), '[', i=2, j=1:2) > ) > > HTH, > > Chuck > >> or should I really stick with: >> >> lapply(lapply(x1, '[[', 3), function(x) x[2,]) >> >> ? >> >> Thank you very much, >> benilton >> > > -- > Charles C. Berry Dept of Family/Preventive Medicine > cberry at ucsd edu UC San Diego > http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego 92093-0901 > > ______________________________________________ > R-help@r-project.org 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.
______________________________________________ R-help@r-project.org 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.
