Yeah, it works fine now. I think I need to modify my function to check for factor.
Regards, C On 10/3/07, Duncan Murdoch <[EMAIL PROTECTED]> wrote: > On 03/10/2007 2:23 AM, Chung-hong Chan wrote: > > Thanks for your answer. But I have a strange question that I don't > > know how to explain and I really don't know how to spot the > > problematic part. > > > > Suppose I have a long list of age, gender and bmi from a data.frame > > called msltdata. > > > >> age <- msltdata$age > >> gender <- msltdata$data > >> bmi <-msltdata$bmi > >> age > > [1] 5 10 14 > >> gender > > [1] 0 0 0 > > Levels: 0 1 > > gender is a factor. The values are stored as indices into the Levels > vector, so 0 is stored as 1 and 1 would be stored as 2. > > Factors commonly arise when you read a dataset from a file, and R thinks > one of the columns is a set of character values rather than numbers. > > To convert gender to a numeric value, you can do this: > > gender <- as.numeric(as.character(gender)) > > but I'd recommend avoiding factors in the first place. > > Duncan Murdoch > > >> bmi > > [1] 17.17693 16.40702 16.87695 > >> mapply(bmisds,age,gender,bmi) > > > > however, when I try to create the vectors once again using the same data, > > i.e. > >> age <- c(5,10,14) > >> gender <- c(0,0,0) > >> bmi <- c(17.17693,16.40702,16.87695) > >> mapply(bmisds,age,gender,bmi) > > > > This time, I can get the correct calculation. > > Would anyone please give me some hints to find out what's went wrong? > > > > Regards, > > C > > > > > > On 10/3/07, Christos Hatzis <[EMAIL PROTECTED]> wrote: > >> Instead of > >> > >>> bmisds(age,gender,bmi) > >> Try the vectorized version > >> > >>> mapply(bmisds, age, gender, bmi) > >> See ?mapply > >> > >> -Christos > >> > >> > >> > >>> -----Original Message----- > >>> From: [EMAIL PROTECTED] > >>> [mailto:[EMAIL PROTECTED] On Behalf Of Chung-hong Chan > >>> Sent: Wednesday, October 03, 2007 12:31 AM > >>> To: [EMAIL PROTECTED] > >>> Subject: [R] How to modify function for list > >>> > >>> Dear R Gurus, > >>> > >>> I have a function which calculate the BMI standard deviation > >>> score based on the age and gender specific L, M, S value. > >>> I have written a function like this > >>> > >>> bmisds <- function (age, gender, bmi){ > >>> if (age ==1 & gender ==1) > >>> { > >>> bmif <- c(-1.013,16.133,0.07656) > >>> } > >>> else if (age ==1 & gender ==0) > >>> { > >>> bmif <- c(-1.79,16.421,0.07149) > >>> } > >>> else if (age == 2 & gender == 1) > >>> { > >>> bmif <- c(-1.403,15.58,0.07342) > >>> } > >>> else if (age == 2 & gender == 0) > >>> { > >>> bmif <- c(-2.045,15.861,0.07116) > >>> } > >>> .... > >>> > >>> (((bmi/bmif[2])**bmif[1] -1)/(bmif[1]*bmif[3])) } > >>> > >>> This function work when I supply a single variable, e.g. > >>> bmisds(1,0,16) > >>> > >>> When I try it with a list, e.g. > >>> age <- c(12,13,14) > >>> gender <- c(0,1,1) > >>> bmi <- c(14,15,16) > >>> bmisds(age,gender,bmi) > >>> > >>> This function give me wrong answer and error msg. > >>> Warning messages: > >>> 1: the condition has length > 1 and only the first element > >>> will be used in: if (age == 1 & gender == 1) { > >>> > >>> > >>> How can I midify this function to work with list/vector? > >>> > >>> regards, > >>> C > >>> > >>> > >>> -- > >>> CH Chan > >>> Research Assistant - KWH > >>> http://www.macgrass.com > >>> > >>> ______________________________________________ > >>> R-help@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. > >>> > >>> > >> > >> > > > > > > -- CH Chan Research Assistant - KWH http://www.macgrass.com ______________________________________________ R-help@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.
