Hi all: In studying the code for bioconductor, I found something that I don't understand. The function implementation that I can not understand is "maLowessLines." The function is listed below. The syntex that I don't understand is "function(x, y, z)". It appears that this is a function within a function (maLowessLines). What is the name of this function? Where does it get the values of x, y, z? Any hints and suggestions will be greatly appreciated. Thanks! ====================================================================== ====== =================================== maLowessLines <- function (subset = TRUE, f = 0.3, col = 2, lty = 1, lwd = 2.5, ...) { function(x, y, z) { subset <- maNum2Logic(length(x), subset) g <- unique(z[subset]) if (length(col) < length(g)) col <- rep(col[1], length(g)) if (length(lty) < length(g)) lty <- rep(lty[1], length(g)) for (i in (1:length(g))) { which <- z[subset] == g[i] xx <- x[subset][which] yy <- y[subset][which] ind <- is.na(xx) | is.na(yy) | is.infinite(xx) | is.infinite(yy) fit <- lowess(xx[!ind], yy[!ind], f = f) lines(fit, col = col[i], lty = lty[i], lwd = lwd, ...) } } } Weicheng Shen, Ph.D. Senior Image Analyst Science Applications International Corporation 1710 SAIC Drive Mail Stop 2-6-9 McLean, VA 22102 (703) 676-4189

Hi, Functions do not have to have names. The name is merely a symbol that is used to identify and manipulate the function, but you can (and we often do) have anonymous functions. For example: (function(x,y){x+y})(4,6) if you type this at the R prompt you will get the value 10 returned. The value of x is 4, of y is 6. The first statement (in parentheses) defines a function. The second set of parentheses indicated that you want to apply that function to the arguments given (4 and 6). There are a number of resources on S language programming available to help with understanding the language (some free, others not). Robert On Fri, May 16, 2003 at 09:48:38AM -0400, SHEN, WEICHENG . wrote: > > Hi all: > > In studying the code for bioconductor, I found something that I don't > understand. The function implementation that I can not understand is > "maLowessLines." The function is listed below. The syntex that I don't > understand is "function(x, y, z)". It appears that this is a function within > a function (maLowessLines). What is the name of this function? Where does it > get the values of x, y, z? Any hints and suggestions will be greatly > appreciated. Thanks! > > ==================================================================== ======== > =================================== > > > maLowessLines <- function (subset = TRUE, f = 0.3, col = 2, lty = 1, lwd = > 2.5, > ...) > { > function(x, y, z) { > subset <- maNum2Logic(length(x), subset) > g <- unique(z[subset]) > if (length(col) < length(g)) > col <- rep(col[1], length(g)) > if (length(lty) < length(g)) > lty <- rep(lty[1], length(g)) > for (i in (1:length(g))) { > which <- z[subset] == g[i] > xx <- x[subset][which] > yy <- y[subset][which] > ind <- is.na(xx) | is.na(yy) | is.infinite(xx) | > is.infinite(yy) > fit <- lowess(xx[!ind], yy[!ind], f = f) > lines(fit, col = col[i], lty = lty[i], lwd = lwd, > ...) > } > } > } > > Weicheng Shen, Ph.D. > Senior Image Analyst > Science Applications International Corporation > 1710 SAIC Drive > Mail Stop 2-6-9 > McLean, VA 22102 > (703) 676-4189 > > _______________________________________________ > Bioconductor mailing list > Bioconductor@stat.math.ethz.ch > https://www.stat.math.ethz.ch/mailman/listinfo/bioconductor -- +--------------------------------------------------------------------- ------+ | Robert Gentleman phone : (617) 632-5250 | | Associate Professor fax: (617) 632-2444 | | Department of Biostatistics office: M1B20 | | Harvard School of Public Health email: rgentlem@jimmy.harvard.edu | +--------------------------------------------------------------------- ------+

Hi Weicheng, ..to follow up on Robert's email: the scoping rules are different from what many people are used from other languages like C or Matlab, and are nicely described in "Lexical Scope and Statistical Computing" by R. Gentleman and R. Ihaka, available from http://cran.r-project.org/doc/misc/ Best regards Wolfgang ------------------------------------- Wolfgang Huber Division of Molecular Genome Analysis German Cancer Research Center Heidelberg, Germany Phone: +49 6221 424709 Fax: +49 6221 42524709 Http: www.dkfz.de/mga/whuber