[R] Can one write a procedure in R like for instance in Maple ?
Liaw, Andy
andy_liaw at merck.com
Mon Jan 23 21:33:06 CET 2006
Thomas Lumley has some notes that might be very helpful for you:
http://faculty.washington.edu/tlumley/Rcourse/
Deepayan Sarkar also has some notes that might be of interest:
http://www.cs.wisc.edu/~deepayan/SIBS2005/
Andy
From: Baronin P. Storch von
>
>
> Dear R-wizards!
>
> I have been learning on my own how to use this fantastic
> program.. but I agree with some people that even with the
> manuals, the faq and so on.. when you are sitting fully
> alone.. progress can be ... slow... very slow indeed.. In
> fact sometimes, looking at the "solutions" provided by some
> of you- I am just flabbergasted to the point that I couldn't
> figure out how to come up with them myself (sometimes I don't
> even understand them :-( )
>
> But after spending around three weeks on this, and starting
> to get fairly obsessed with it, I decided I shall ask for
> help,'cause i can't figure out in the documentation where I
> should look for this.
>
> In Maple when I want to automatize something boring I write a
> procedure..
> here I am not too sure.. how to bind together a few
> statements- most of which are functions... sounds like it
> would make up a personnal macro..
> I am sure I am doing things in such a primitive way that the
> R-specialists will wince.. but that's how it goes with beginners!
>
> Set up.
>
> I have 4 fairly large data base with unequal number of lines
> (around 1200-1500), but identical number of columns (162)-years.
>
> for each column, I construct a data-frame with the
> corresponding column of DB1, then from DB2, .. DB4.
>
> This yields a data.frame in which many data are NA- some are
> real NAs some others are because I have to take the max of
> the lines. In any case, the number of NAs of each of these 4
> columns is not identical.
>
> I extract (by sorting and creating 4 new vectors) 4 vectors
> of variable length
> -the relevant and interesting data- to whom I wish to apply
> some standardized treatment: that is normality with say
> Shapiro-Wilks, Levene, etc.. Kruskal-Wallis and probably
> other things..
>
> I am not showing my tasks because I do not think that I want
> to bother the readers with this,, rather ask for general
> remarks ( you can provide examples of your own).
>
> For each column I want to write the results in a table.. and
> append these resulta for each column.
>
> I was fairly efficient at doing that for a particular column,
>
> but then the simple thought of apply this "list of tasks"
> 162 times.. makes me..
> feel that there should be a way.... to speed up my
> execution.. (a loop)
>
> However I have not been able to create a super "function" (or
> procedure) that could tie all these statements together in a
> sensible fashion.. because each time the data.frame created
> is generated by a function.. and somehow i still did not
> figure out how to write a function of functions
> and then maybe a loop do for all values of dates =1:162 this
> function..
>
> (all the stuff I tried failed, because I was indexing objects
> that were also indexed.. I am vague.. but then retracing a 3
> weeks of trials and errors errors errors errors ...\infty :-)
> is cumbersome)
>
>
> 1. Could anybody give me suggestions where to look and maybe
> unveil the tricks of the function of functions ..
>
> ideally I would construct a loop executing a super function..
> whose results would be dumped in a file (write.table)
> appending each time the result of the loop i..
>
> but I was not able to construct that...
> should I make a wiser use of these "apply, tapply, sapply"
> marvels? I dunno.
> does something like for (i in 1:G){sapply(b(i),sw)} were
> b(i) is the dataframe for column i, and SW is a function
> (super function-procedure) make sense in R?
>
> I see that there are some fully esoterical paragraphs on
> things that seem to be relevant in the manuals.. but..
> esoterical.. I cannot make sense of them... vicious circle..
>
>
> Thank you in advance for any courageous that would give me a hint..
>
> Christina
>
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