On Dec 2, 2009, at 5:00 PM, Peng Yu wrote:
On Wed, Dec 2, 2009 at 3:51 PM, David Winsemius <dwinsem...@comcast.net
> wrote:
On Dec 2, 2009, at 4:33 PM, Peng Yu wrote:
intersect(c(1,3,2),c('1','3')) # note x is numeric and y is
character
[1] "1" "3"
Apparently, intersect() treats num as string. But this is not
documented in the help. Could somebody add it in the future
version of
R?
It is documented that intersect will return a value of that is same
mode as
its "y" argument. How could it be any more clear?
Also according to the help, the argument should not have duplicated
elements.
That's not what my help page says. It says that "conceptually" they
won't
have them, but immediately thereafter it says:
"Details
Each of union, intersect, setdiff and setequal will discard any
duplicated
values in the arguments, and they apply as.vector to their
arguments (and so
in particular coerce factors to character vectors)."
Unfortunately, R does not have a package that will ensure that
users will
read the help pages carefully.
I didn't read Details.
If you are not going to read the help page, then please stop asking
for corrections to it.
Because I was interested in the arguments. The
problem of some R document is that some information should gathered
together are spread into multiple places. In particular, in the help
of intersect, the first line of 'Details' should be merged with
'Argument' to make the help page clear and easy to read.
--
David
But I tried the following example, it seems that it doesn't
matter where there are duplicated elements or not. Should the help
be
corrected? Or somebody could provide me with an example that make
intersect() fails if there are duplicated elements?
x=c(3,1,2,1,7)
y=c(5,1,4,2,3,8,1)
x
[1] 3 1 2 1 7
y
[1] 5 1 4 2 3 8 1
intersect(x,y)
[1] 3 1 2
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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