Patrick,
1. Implicit intercepts. Implicit intercepts are not too bad for the main
model, but they creep in occasionally in strange places where they might not
be expected. For example, in some of the variance structures specified in
lme, (~x) automatically expands to (~1+x). Venables said in the "Exegeses"
paper: "For teaching purposes it would be useful to have a switch that
required users to include the intercept term in formulae if it is needed.
This would deï¬nitely help more students than it would hinder. In other words
it should be possible to override the automatic intercept term."
2. Working with colors. There are a number of functions in R for working
with colors and since colors can be specified by palette number, name,
hexadecimal string, values between 0 and 1, or values between 0 and 256,
things can be confusing. One problem is that not all functions accept the
same type of arguments or produce the same type of return values. For
example, the awkward need of "t" and conversion to [0,255] in adding alpha
levels to a color:
rgb(t(col2rgb(c("navy","maroon"))),alpha=120,max=255)
3. Factors. R tries to convert everything that it possibly can into a
factor. Except, occasionally, it doesn't try. Further, after sub-setting
data so that some factor levels have no data, too many functions fail. I
shouldn't need to use "drop.levels" from gdata package all over the place to
keep automated scripts running smoothly. Let's not forget:
R> as.numeric(factor(c(NA,0,1)))
[1] NA 1 2
4.
is.list(list(1)[1])
[1] TRUE
is.matrix(matrix(1)[1,])
[1] FALSE
Ouch. Ouch. Ouch.
5. Most useful: "apropos" and Rseek.
Best,
Kevin
On Thu, Feb 25, 2010 at 11:31 AM, Patrick Burns <pbu...@pburns.seanet.com>wrote:
> * What were your biggest misconceptions or
> stumbling blocks to getting up and running
> with R?
>
> * What documents helped you the most in this
> initial phase?
>
> I especially want to hear from people who are
> lazy and impatient.
>
> Feel free to write to me off-list. Definitely
> write off-list if you are just confirming what
> has been said on-list.
>
> --
> Patrick Burns
> pbu...@pburns.seanet.com
> http://www.burns-stat.com
> (home of 'The R Inferno' and 'A Guide for the Unwilling S User')
>
> ______________________________________________
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> PLEASE do read the posting guide
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> and provide commented, minimal, self-contained, reproducible code.
>
--
Kevin Wright
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