Message-ID: <f8e6ff050904261553lb63e992p23d460374eadaaef@mail.gmail.com>
Date: 2009-04-26T22:53:45Z
From: Hadley Wickham
Subject: eager to learn how to use "sapply", "lapply", ...
In-Reply-To: <6B32C438581E5D4C8A34C377C3B334A403B1ED49@FBCMST11V04.fbc.local>
Have a look at the plyr package and associated documentation -
http://had.co.nz/plyr
Hadley
On Sun, Apr 26, 2009 at 12:42 PM, <mauede at alice.it> wrote:
> After a year my R programming style is still very "C like".
> I am still writing a lot of "for loops" and finding it difficult to recognize where, in place of loops, I could just do the
> same with one line of code, using "sapply", "lapply", or the like.
> On-line examples for such high level function do not help me.
> Even if, sooner or later, I am getting my R scripts to do what I expect, I would really like to shake my C programming style off.
> I am staring at my R script and thinking "how can I improve it ?"
> For instance, I have a lot of loops similar to the following one and wonder whether I can replace them with a proper call to a high level R function that does the same:
>
> ? ?Nstart <- Nfour/(2^Lev) + 1
> ? ? Nfinish <- Nstart -1 + Nfour/(2^Lev)
> ? ? LengLev <- Nfinish - Nstart + 1
> ? ? NW <- floor(LengLev*N/Nfour)
> ? ? if(NW > 0){
> ? ? ? for(j in Nstart:(Nstart + NW -1)){
> ? ? ? ? ?Dw <- abs(Y[j])
> ? ? ? ? ?Rnorm <- Rnorm + Dw^2
> ? ? ? }
> ? ? }
>
>
> Thank you very much for helping me get better.
> Maura
>
>
>
>
>
> tutti i telefonini TIM!
>
>
> ? ? ? ?[[alternative HTML version deleted]]
>
> ______________________________________________
> 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.
>
--
http://had.co.nz/