howto calculate column means in data frame
Hi Jim, Using ?lapply with ?colMeans should do the trick. Here is a little sample: eg <- list(mtcars, mtcars) # mtcars data frame twice in a list resultsmean <- lapply(eg, colMeans) # calculate column means for each element of "eg" resultsmean # show the results Hope this helps, Josh
On Sun, Apr 10, 2011 at 8:27 AM, Maas James Dr (MED) <J.Maas at uea.ac.uk> wrote:
Long story short, I have a big iterative procedure that produces a long list of data.frames such as the one called "results" here. ?Is there an easy way to produce a similar list of data.frames comprised of the mean of each of the columns in results, such that it ends up like the one I've shown in "resultsmean" below? I've tried apply and lapply, still not got the correct arguments. ?As usual, TIA. Jim
results
[[1]] ? ? ? name ? ?LOR23 ? ? ? BIA23 ? ? ? MSE23 ? ? ? ? ?H0R23 1 0.2111122 ? -1.012228 ? -0.095937 ? ?0.035650 ? ? ? ?1.00 2 0.2111122 ? -0.836300 ? ?0.079991 ? ?0.042322 ? ? ? ?0.75 3 0.2111122 ? -0.518631 ? ?0.397659 ? ?0.214593 ? ? ? ?0.50 [[2]] ? ? ? name ? ?LOR23 ? ? ? BIA23 ? ? ? MSE23 ? ? ? ? ?H0R23 1 0.2211122 ? -0.724630 ? ?0.191660 ? ?0.051308 ? ? ? ? ? 1 2 0.2211122 ? -0.781812 ? ?0.134478 ? ?0.033872 ? ? ? ? ? 1 3 0.2211122 ? -0.522109 ? ?0.394181 ? ?0.164628 ? ? ? ?0.75 would like
resultsmean
[[1]] ? ? ? name ? ?LOR23 ? ? ? BIA23 ? ? ? MSE23 ? ? ? ? ?H0R23 1 0.2111122 ? -0.78333 ? ?0.12734 ? ? 0.097160 ? ? ? ?0.75 [[2]] ? ? ? name ? ?LOR23 ? ? ? BIA23 ? ? ? MSE23 ? ? ? ? ?H0R23 1 0.2211122 ? -0.67566 ? ?0.2400 ? ? ?0.08266 ? ? ? ? 0.916 =============================== Dr. Jim Maas University of East Anglia
______________________________________________ R-help at r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Joshua Wiley Ph.D. Student, Health Psychology University of California, Los Angeles http://www.joshuawiley.com/