On Jun 25, 2015, at 11:52 PM, Steven Yen wrote: > Thanks Davis. But actually, the line is legitimate:
I didn't say it was illegitimate, only confusing. > > if (inherits(wt,what="character")) wt<-data[,wt] What you are asking for is known in R as non-standard evaluation. Examples include the library and help functions. About a page and a half down the code for `help`, you see this line, following a tryCatch test to see if the argument is character: stopic <- deparse(substitute(topic)) That returns a character value from a symbol. About three pages inside the code for `library` you also see this after a test for 'character'-ness: package <- as.character(substitute(package)) -- David. > > because, coming down with wt being characters, the part wt<-data[,wt] then > picks up variables data$wt. The call > > wmean(mydata,wt="weight") > > actually goes OK. I was hoping to figure out a way to fix the wmean routine > some how so that I can call with > > wmean(mydata,wt=weight) > > Good to know there is a better way to initialize the vector Mean and and a > better list command. Thank you! > > On 6/26/2015 2:39 AM, David Winsemius wrote: >> >> On Jun 25, 2015, at 7:48 PM, Steven Yen wrote: >> >>> Thanks to all for the help. I have learned much about "inherit" and >>> "class". I like to know about one additional option, and that is to use a >>> calling parameter without the quotation marks, similar to the linear >>> regression syntax: >>> >>> lm(data=mydata,weights=wt) >>> >>> Below is a simple set of codes to calculate weighted means with generated >>> data in data frame "mydata". As annotated below, I like the following call >>> to work (without the quotations): >>> >>> wmean(mydata,wt=weight) >> >> Let's start with the call. If you are to execute this, then names `mydata` >> and `weight` each must have a value. >> >>> >>> Thank you! >>> ---- >>> >>> mydata<-matrix(1:20,ncol=2) >> >> OK. There is a value having been assigned to `mydata` >> >>> mydata<-cbind(mydata,runif(10,0,1)) >> >> And now augmented. >> >>> colnames(mydata)<-c("y","x","weight") >> >> And a names attribute added for its columns. >> >>> mydata<-as.data.frame(mydata) >>> >>> wmean <- function(data,wt){ >>> if (inherits(wt,what="character")) wt<-data[,wt] >>> wt<-wt/mean(wt) >> >> Here's the problem. If `wt` was of mode "character", then you cannot divide >> it by a number, since the RHS will be evaluated first. You really should >> read the error messages! >> >> Perhaps you meant: >> >> wt <- data[, wt]/mean(data[ , wt] >> >> But if you did, then it's rather confusing (but possible) to assign the >> value to the same name as the column of the matrix. >> >> >>> Mean<-NULL >> >> Why do that? If you remove it from the workspace then you cannot assign a >> value using indexed assignment as you apparently intend to do. Should have >> been >> >> Mean <- numeric( ncol(data) ) >> >> >>> for (i in 1:ncol(data)){ >>> Mean[i] <- sum(data[,i]*wt)/sum(wt) >> >> There is a bit of a confusion here. `wt` started out as a character value. I >> guess you could do this. >> >>> } >>> list("Mean: ",Mean) >> >> Wrong syntax for lists. Suspect you want >> >> list(Mean=Mean) >> >> >>> } >>> wmean(mydata,wt="weight") # This works >>> wmean(mydata,wt=weight) # <= Like this to work >> >> So were you planning to execute this first? >> >> weight="weight" #? >> > > -- > Steven Yen > My e-mail alert: > https://youtu.be/9UwEAruhyhY?list=PLpwR3gb9OGHP1BzgVuO9iIDdogVOijCtO David Winsemius Alameda, CA, USA ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.