[R] "chronological" ordering of factor in lm() and plot()

Eric C. Jennings matheric at myuw.net
Sat Apr 16 06:29:14 CEST 2005


I am trying to do some basic regression and ANOVA on cycle times (numeric
vectors) across weekdays (character vector), where I have simply labelled my
days as:
days<- c("mon","tue","wed"...etc).
(NOTE: There are actually multiple instances of each day, and the data is
read-in from a .dat file.)

I have no trouble at all with the actual number crunching, It is the
"proper" ordering of the factor that I am asking about. R first alphabetizes
it("fri","mon","thu"...) before doing the work of lm(), aov() and especially
plot().

I have tried as.ordered(factor( )), but that doesn't do anything.
If I re-assign levels() in the way that I want, that just renames the the
levels of the factor but does not reorder it internally.
I've looked at chron(), but that seems to entail using a numeric vector
instead of a character vector.

How can I get it to "properly" (chronologically) order the factor. (In some
ways I'm thinking that all I can do is:
days<- c("a.mon","b.tues","c.wed"...etc)

Thanks for all that you can do
Eric Jennings
matheric at u.washington.edu
matheric at myuw.net




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