Prof Brian Ripley wrote: > Interchange 1 and 2 (see ?apply: Andy was answering the subject line, not > that in the body). > > However, Max asked also for column medians of a data frame, for which use > sapply(DF, median)
By the way, what is the preferred code for column-wise calculation on *all numeric* data in a data frame? > sapply(DF, median) which considers the list and then simplifies the results down to a vector or matrix,... or > apply(DF, 2, median) which first convert into a matrix and then do the calculation on it? Best, Philippe Grosjean > I didn't understand the question, and it seems I was not alone :) > > On Fri, 20 Jan 2006, Philippe Grosjean wrote: > > >>Note that there is a confusion here: 1st dimension is row, 2nd dimension >>is column for matrix & data.frame. > > > And the dim arg to apply is the one you want the answer to have. > > A <- matrix(runif(6), 2, 3) > apply(A, 1, median) # row medians > apply(A, 2, median) # col medians > > > >>So, if the question is about "rowMedian", you have: >> >> >>>rowMedian <- function(x, na.rm = FALSE) >>> apply(x, 2, median, na.rm = na.rm) >> >>Now, you ask for the "median for specified columns", which should be as >>Andy proposes you, or, if you really want a colMedian function: >> >> >>>colMedian <- function(x, na.rm = FALSE) >>> apply(x, 1, median, na.rm = na.rm) >> >>Best, >> >>Philippe Grosjean >> >>Liaw, Andy wrote: >> >>>apply(x, 1, median) should do it. If not, you need to explain why. >>> >>>Andy >>> >>>-----Original Message----- >>>From: Max Kauer >>>Sent: Friday, January 20, 2006 10:24 AM >>>To: [email protected] >>>Subject: [R] function for rowMedian? >>> >>> >>>Hi >>>is anybody aware of a function to calculate a the median for specified >>>columns in a dataframe or matrix - so analogous to rowMeans? >>>Thanks >>>Max > > ______________________________________________ [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
