[R] extending strsplit to handle missing text that doesn't have the target on which to split

[Chris Evans]

I am sure there is an obvious answer to this that I'm missing but I
can't find it.  I'm parsing headers of Emails and most have a date like
this:
   "Wed, 16 Nov 2005 05:28:00 -0800"
and I can parse that using:

tmp.dat.data <- matrix(unlist(strsplit(headers$Date.line,",")),
    ncol = 2, byrow = TRUE)
before going on to look at the day and date/time data.

However, a very few headers I want to parse are missing the initial day
of the week and look like this:
   "15 Nov 2005 09:10:00 +0100"

That means that my use of strsplit() results in that date/time part
being all of the item in the list for those entries so the effect of
matrix(unlist()) is to pull the next list entry "up" in the matrix.
Because I happened to have only two errant entries I didn't see what was
happening for a moment. (An odd number gives a warning message about
dimensions not fitting but an odd number has silently moved things
up/left so doesn't: no quarrel with that from me, my stupidity that I
was slow to see what was happening!)

I'm sure I should be able to find a simple way to get around this but at
the moment I can't.

Here's a simple, reproducible example:

dat <- c("Tue, 15 Nov 2005 09:44:50 EST",
         "15 Nov 2005 09:10:00 +0100",
         "Tue, 15 Nov 2005 09:44:50 EST",
	 "Tue, 15 Nov 2005 16:29:57 +0000",
	 "Wed, 16 Nov 2005 07:00:45 EST",
	 "Wed, 16 Nov 2005 05:28:00 -0800",
	 "Wed, 16 Nov 2005 14:06:21 +0000",
         "15 Nov 2005 09:10:00 +0100")
tmp.dat.data <- matrix(unlist(strsplit(dat,",")),ncol = 2, byrow = TRUE)


tmp.dat.data comes out as a 7x2 matrix contents:

     [,1]                          [,2]
[1,] "Tue"                         " 15 Nov 2005 09:44:50 EST"
[2,] "15 Nov 2005 09:10:00 +0100"  "Tue"
[3,] " 15 Nov 2005 09:44:50 EST"   "Tue"
[4,] " 15 Nov 2005 16:29:57 +0000" "Wed"
[5,] " 16 Nov 2005 07:00:45 EST"   "Wed"
[6,] " 16 Nov 2005 05:28:00 -0800" "Wed"
[7,] " 16 Nov 2005 14:06:21 +0000" "15 Nov 2005 09:10:00 +0100"

I'd like an 8x2 matrix with tmp.dat.data[2,1] == "" and
tmp.dat.data[8,1] == ""

I'm sure there must be a simple way to achieve this by rolling a
slightly different variant of strsplit that pads things and then
applying that to the input vector but I'm failing to see how to do this
at the moment.

TIA,

Chris

--
Applied researcher, neither statistician nor programmer!