Bryan L. Brown <stonefly <at> mail.utexas.edu> writes: : : Sorry if these questions have been asked recently--I'm new to this list. : : I'm primarily a Matlab user who is attempting to learn R and I'm searching for possible equivalents of : commands that I found very handy in Matlab. So that I don't seem ungrateful to those who may answer, I HAVE : determined ways to carry out these processes in 'brute force' sorts of ways in R code, but they lack the : elegance and simplicity of the Matlab commands. Also, if you know that no such commands exist, that bit of : knowledge would be helpful to know so that I don't continue fruitless searches. : : The first is Matlab's 'find' command. : This is one of the most useful commands in Matab. Basically, if X is the vector : : X=[3, 2, 1, 1, 2, 3] : : the command : : 'find(X==1)' : : would return the vector [3, 4] which would indicate that the vector X had the value of 1 at the 3 and 4 : positions. This was an extremely useful command for subsetting in Matlab. The closest thing I've found in : R has been 'match' but match only returns the first value as opposed to the position of all matching values. : : The second Matlab command that I'd like to find an R equivalent for is 'end'. 'end' is just a simple little : command that indicates the end of a row/column. It is incredibly handy when used to subset matrices like : : Y = X(2:end) : : and produces Y=[2, 1, 1, 2, 3] if the X is the same as in the previous example. This cutsie little command was : extremely useful for composing programs that were flexible and could use input matrices of any size : without modifying the code. I realize that you can accomplish the same by Y <- X[2:length(X)] in R, but this : method is ungainly, particularly when subsetting matrices rather than vectors. : : If anyone has advice, I'd be grateful,
In addition to the answers you already got there are: X[-1] # all but first element of a vector mat[,-1] # all but first column mat[-1,] # all but first row tail(X, 8) # last 8 elements of vector or last 8 rows of data frame Also be sure to check out Robin Hankin's "R and Octave" referenced at: http://cran.r-project.org/other-docs.html ______________________________________________ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
