## A shortcut function for install.packages() and library()

I enjoy trying difference kind of R packages. Since I have more than 1 computers (1 at home, 1 at office and a laptop)

it is troublesome to check whether I have installed some new packages for each computer. Therefore i wrote a function to load and install packages at once. If the package does not exist, then the it will be downloaded from CRAN and be loaded it.

packages<-function(x, repos="http://cran.r-project.org", ...){ x <- deparse(substitute(x)) if (!require(x,character.only=TRUE)){ install.packages(pkgs=x, repos=repos, ...) require(x,character.only=TRUE) } } packages(Hmisc)

Thanks richierocks for the suggestion of using deparse(substitute(x)) in the code.

richierocks’s

## A quick way to do row repeat and col repeat (rep.row, rep.col)

Today I worked on a simulation program which require me to create a matrix by repeating the vector n times (both by row and by col).

Even the task is extremely simple and only take 1 line to finish(10sec), I have to think about should the argument in rep be each or times and should the argument in matrix is nrow or ncol. It distracted me from the original task i am working on.

Just now, I wrote a function rep.row and rep.col to do what I really want to do. Next time, i don’t have to worry about how to use the matrix and rep command to repeat an vector to form a matrix!

Code

rep.row<-function(x,n){ matrix(rep(x,each=n),nrow=n) } rep.col<-function(x,n){ matrix(rep(x,each=n), ncol=n, byrow=TRUE) }

x is the vector to be repeated and n is the number of replication. Example:

> rep.row(1:3,5) [,1] [,2] [,3] [1,] 1 2 3 [2,] 1 2 3 [3,] 1 2 3 [4,] 1 2 3 [5,] 1 2 3 > rep.col(1:3,5) [,1] [,2] [,3] [,4] [,5] [1,] 1 1 2 2 3 [2,] 1 1 2 3 3 [3,] 1 2 2 3 3

I am sure it should appear in some packages, but it would be faster for me to write it out than find it out!