[R] hashing using named lists

Prof Brian Ripley ripley at stats.ox.ac.uk
Thu Nov 18 18:50:40 CET 2004

On Thu, 18 Nov 2004, ulas karaoz wrote:

> hi all,
> I am trying to use named list to hash a bunch of vector by name, for 
> instance:
> test = list()
> test$name = c(1,2,3)
> the problem is that when i try to get the values back by using the name, the 
> matching isn't done in an exact way, so
> test$na is not NULL.
> is there a way around this?

?match on the names

> Why by default all.equal.list doesnt require an exact match?

What do you mean by that?  It (by default or not) tests all the 
attributes, including the names:

test <- list(name=1:3)
test2 <- list(na=1:3)
all.equal(test, test2)
[1] "Names: 1 string mismatches"

Now, all.equal does not require an exact match, deliberately: that is what 
identical() is for:

identical(test, test2)

> How can I do hashing in R?


Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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