[R] Simulation)

Wacek Kusnierczyk Waclaw.Marcin.Kusnierczyk at idi.ntnu.no
Thu May 14 13:11:56 CEST 2009

Peter Flom wrote:
>  As a beginner, I agree .... the for loop is much clearer to me.  
>> well, that's quite likely.  especially given that typical courses in
>> programming, afaik, include for looping but not necessarily functional
>> stuff -- are you an r beginner, or a programming beginner? 
> Both.  My PhD is in psychometrics, and, both in course work and since then
> I've learned a good bit of statistics, but very little programming.  I've 
> picked up a little SAS programming over the years, but not much.

don't really know sas, but i guess for looping is of essence there,
while mapping is not.

> But the loop (at least for me) translates into English more directly than the
> lapply statement does.

lapply easily translates to 'apply this to every item there', which is
roughly an alternative version of 'for each item in there, do this with
the item'.

>> the structure and interpretation of computer programs (sicp) by abelson
>> & sussman, a beautiful cs masterpiece, introduces mapping (lapplying) on
>> p. 105, mentions a for-each control abstraction only in an exercise two
>> pages later, and does not really discuss for looping as such. 
>> functional mapping over stateless objects is, in general, *much* easier
>> to reason with than procedural looping over stateful objects -- an issue
>> a beginner may not be quite aware of, and learning the basic for loop
>> stuff without caring about, e.g., concurrent access to shared mutable
>> state etc. may indeed make the impression that for  loops are easier. 
> Would that be a good book for a beginner?

both yes and no.  this is a book that can be used by an absolute
beginner in programming, but if you're focused on statistics, you're
unlikely to enjoy it, at least not as a practical introduction.  but
it's a good read, and contains quite a lot of useful ideas anyway.


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