(PR#8777) strsplit does [not] return correct value when spliting ""
Prof Brian Ripley wrote:
On Mon, 17 Apr 2006, Charles Dupont wrote:
[...]
The man page states in the value section that strsplit returns:
A list of length 'length(x)' the 'i'-th element of which contains
the vector of splits of 'x[i]'.
It mentions no change in behavior if the value of x[i] = "".
There is none, for there are no splits in that case. I did ask you to point to the documentation of the rule you are assuming, and I can't find any.
No, the documentation does not explicitely mention this, but shouldn't "there
are not splits" mean: So the string is returned unchanged?
Consider these examples - I don't think that's the behavior you'd expect
unless told otherwise:
a <- "a"
b <- ""
a == strsplit (a, ",") # TRUE
b == strsplit (b, ",") # FALSE
So, maybe there is a general rule that empty elements get purged?
strsplit ("a,,b", ",")
[[1]]
[1] "a" "" "b"
strsplit ("a", "a")
[[1]]
[1] ""
Apparently not so. Then why does an empty string get "split" to a non-existent
string?
Note: I don't really care much about what the behavior is, but if the
described behavior is indeed intended, I think it should be documented. IMO
it's pretty counter intuitive.
Regards
Thomas
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