[R] question about technieque do with large computation

[Uwe Ligges]

ronggui wrote:

> The green book tells:"The basic technique is classic :keep it simple ."A long ,complicated expression or function is less fravorable than" a relatively small computations that combines calls to a few other functions to perform its tasks."
> 
> But I don't get the point totally.Can anyone give me an example to make me understand this rules totally?
> 
> ps:
> Is it mean that f1 is better than f2?  Thank you!
> 
> 
> f1<-function(x){
> n<-length(x)
> s<-sum(x)
> m<-s/n}
> 
> f2<-
> function(x){
> m<-sum(x)/length(x)} 				


No, it means collecting sensible small parts of the code into separate
functions as in

f1 <- function(x, .....){
 x1 <- f1a(x, ......)
 x2 <- f1b(x1, .....)
 x3 <- f1a(x2, .....)
 f1c(x1, x2, x3, .....)
}

which is "better" than

f2 <- function(.....){
##
## many lines calculating stuff as in f1a
##
## many lines calculating stuff as in f1b
##
## many lines calculating stuff as in f1a
##
## many lines calculating stuff as in f1c
##
}


Uwe Ligges



> 
> 2005-10-23
> 
> ------
> Deparment of Sociology
> Fudan University
> 
> My new mail addres is ronggui.huang at gmail.com
> Blog:http://sociology.yculblog.com
> 
> 
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