similar to: apply on two lists?

Suppose I run the following code in the R session. At the last prompt '>', I want to retrieve the second command (staring with 'y'). But I have to type up arrow many times, which is very inconvenient. I'm wondering if there is a way to configure R to skip block of code in the history? > x=list(a=c(1,2),b=c(3,4,5)) > y=list(a=c(1,2),b=c(3,4,5)) > lapply(seq(along=x)

Suppose I run the following code in the R session. At the last prompt '>', I want to retrieve the second command (staring with 'y'). But I have to type up arrow many times, which is very inconvenient. I'm wondering if there is a way to configure R to skip block of code in the history? > x=list(a=c(1,2),b=c(3,4,5)) > y=list(a=c(1,2),b=c(3,4,5)) > lapply(seq(along=x)

There are a few version of apply() (e.g., lapply(), sapply()). I'm wondering if there is one that does not return anything but just silently apply a function to the list argument. For example, the plot function is applied to each element in 'alist'. It is redundant to return anything from apply. apply(alist,function(x){ plot each element of alist})

Hi, There are quiet a few different 'apply' functions, such as lapply, sapply and many more. I'm very familiar with the 'Apply' function in Mathematica. Can somebody point me a summary of all the 'apply' functions in R. Also, I'm curious that what 'l' and 's' (and other prefixes) stand for in 'lapply' and 'sapply' Regards, Peng

Hi, I am wonder if there is a function similar 'apply' but it could accept multiple arguments? For example, I have the following matrix. x=matrix(1:6,nr=2) y=matrix(1:6,nr=2) I want to find a function that can be used to compute the linear regression for each pair of rows in the two matrices? multiple_apply(x,y,1,function(u,v){lm(u ~ v)} That is, I wound like something like the above

I use lapply to apply a function to the list 'L'. But of course, the list names in 'X' is not maintained. I'm wondering if there is a function that can maintain the list names as well as apply the function. $ Rscript lapply.R > L=list(x=c('a','b'), y=c('a','b')) > L $x [1] "a" "b" $y [1] "a" "b"

I can exclude columns by column number using '-'. But I wondering if there is an easy way to exclude some columns by column names. > x=cbind(c(1,2),c(3,4)) > x [,1] [,2] [1,] 1 3 [2,] 2 4 > colnames(x)=c('a','b') > x a b [1,] 1 3 [2,] 2 4 > x[,-'a'] Error in -"a" : invalid argument to unary operator > x[,-1] [1] 3 4

There are a number of functions that are dispatched to from split(). > methods('split') [1] split.data.frame split.Date split.default split.POSIXct Is there a way to figure out which of these variants is actually dispatched to when I call split? I know that if the argument is of the type data.frame, split.data.frame will be called? Is it the case that if the argument is not

The following code returns a list with the 2nd element as NULL. I'm wondering what the best way to get rid of NULL element in an 'apply()'s result. > lapply(1:3, function(x) { + if(x==2) { + return(NULL) + } else { + return(x) + } + } + ) [[1]] [1] 1 [[2]] NULL [[3]] [1] 3

Hi, I am wondering if some experienced users would help put the ready-to-run code of the examples in the manuals. It would help new users learn R faster by putting all the examples in an ready-to-run R script file. Can somebody help do so sometime and post the code along with the pdf manuals? http://cran.r-project.org/manuals.html Regards, Peng

Some examples in the help page are too long to be copied from screen. Could somebody let me know some easy way on how to extract the example to a file so that I can play with them?

Hi, Suppose I have the following two matrices. > x=matrix(1:4,nr=2) > y=matrix(5:8,nr=2) I want to join the two matrices to get the following two new matrices. I did a search but I don't find any relevant webpage. Can somebody let me know how to do it? [,1] [,2] [1,] 1 3 [2,] 2 4 [3,] 5 7 [4,] 6 8 [,1] [,2] [,3] [,4] [1,] 1 3 5 7 [2,]

I don't find a function to print a string to file. Would somebody let me know what function I should use?

I got the error. I haven't been able to get a stand along case so that I can show it here. But could somebody give some clue on what could cause this error? Since I never defined xj[i], I don't understand where this error come from. Error in xj[i] : invalid subscript type 'list'

Hi, I'm learning the tutorial. http://llvm.org/docs/tutorial/ I'm wondering if there is already a git repository of the examples in the tutorial so that I don't have to copy the code from the webpage. Thanks! -- Regards, Peng

I found this paper on ANOVA on unequal error variance. Has this be incorporated to any R package? Is there any textbook that discuss the problem of ANOVA on unequal error variance in general? http://www.jstor.org/stable/2532947?cookieSet=1

Hi, I'm wondering if R provide a vi mode in the command line just like other shells such as bash do. Can somebody let me know? Regards, Peng

Hi, x=matrix(1:60,nr=6) I can refer the last 2 rows by x[5:6,] If I don't know the total number of rows is 6, is there a way to refer the last 2 rows? Regards, Peng

read.table terminates the program if the input file is empty. Is there way to let the program continue and return me a NULL instead of terminating the program? $ Rscript read_empty.R > read.table("empty_data.txt") Error in read.table("empty_data.txt") : no lines available in input Execution halted $ cat read_empty.R read.table("empty_data.txt") $ cat

Hi, > x=c(rep(1,3),rep(3,2)) > x [1] 1 1 1 3 3 > duplicated(x) [1] FALSE TRUE TRUE FALSE TRUE > As shown in the above code, 'duplicated' doesn't return 'F' for the first '1' and first '3' in 'x'. I am wondering if there is a function that can return an indicator for any element whether it appears in a vector twice or more. Regards, Peng