# [R] stuff I used to do in Matlab

Philippe Grosjean phgrosje at ulb.ac.be
Fri Sep 14 09:26:37 CEST 2001

I am currently converting Matlab code into R code. All basic matrix
operations in Matlab exist also in R... You just have to find them because
functions names and logic are sometimes a little bit different. You have a
few hints with other answers in this thread. R is strongest in indexing
matrices. It handles also data.frames, factors, etc... with no direct
equivalent in Matlab. You are better to consider you learn a new language
instead of trying to use R as a Matlab-like language. If you do so, I guess
you will prefer R than Matlab for most applications (like I do!). My R code
tend also to be somewhat shorter than Matlab equivalent :-) However, Matlab
code (if run in v. 6) is often faster :-(
All the best,

Philippe Grosjean

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>Hi,
>	I'm new to R, and trying to map stuff I knew how to do in Matlab
>to R. For instances, in matlab, sum(x) gave the column sums of
>matrix(/vector) x. In R it just gives the sum of all the elements,
>regardless of their form (vector or matrix). Is there a simple way to
>return a vector of column sums for a matrix? Also, in Matlab binary
>operators exist for concatenating a matrix onto the end or the bottom of
>another matrix (i.e. horiz or vertically) but no such operators seem to
>exist for R. is there an easy way to concatenate matrices? (I have found a
>way which involves several steps, first creating a new matrix of zeros
>with dimensions based on the dims of the old ones, and then inserting the
>contents of the old matrices into the new one, but this seems very
>cumbersome, esp. since I'm used to being able to do it with something like
>c = [a,b]. Thanks for entertaining my newbie questions

>dave

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