[R] Moving data between R and Matlab back and forth?

[Tribo Laboy]

I have packaged the above posted code as a function and I am posting
it here in case someonw would find it useful in the future.


--------------function begin -------------------------
readMat2df <- function(readfiledata, datastr){
    tmpdata <- readfiledata[[datastr]] # use the string contained in
'datastr' to acccess the data with that name
    tmpdata <- drop(tmpdata)  # Drops all the unnecessary indexes with
length 1 and the list becomes much simpler

    # If any of the contents of each cell is a list then "rbind" its
elements into a single vector and treat it as a factor
    # These elements were represented as cell elements of a cell array
in the MATLAB structure.
    for (k in 1:length(tmpdata)){
        if (mode(tmpdata[[k]]) == "list") {
            tmpdata[[k]]<- as.factor(do.call("rbind", tmpdata[[k]]))
        }
    }

    tmpdf <- as.data.frame(tmpdata)
    return(tmpdf)
}
------------------function end --------------------------------

How to use this thing?

Well suppose you had an R data frame and exported it into  Matlab MAT
v6 format with 'writeMat' function of R.matlab like this:


library(R.matlab)
writeMat("labpc.mat", labpcexport = labpc) #This give the name
'labpcexport' to the ML structure holding the data

Re-load the file in R with 'readMat' like this

labpcfile <- readMat("labpc.mat")

To get back a data frame from the imported MAT file:
1. Find the name of the variable that holds it. To get of all the
variables that were in the MAT file:

names(labpcfile)

2. Pass this name  and the name of the list that holds all imported
MAT data to the function, get a data frame out:

myFavoriteDataFrame <-  readMat2df(labpcfile, " labpcexport")

Hope this is useful for someone.

Regards,

TL