How to split string of characters by commas but keep dates?

I have a string of characters like this in R

ABCDE,"January 10, 2010",F,,,,GH,"March 9, 2009",,,

I would like to do something like str.split() to partition by all combinations of commas and quotation marks into an array of strings, but keep the commas in quotation marks that represent dates so that I get:

ABCDE
January 10, 2010
F
GH
March 9, 2009

Thanks

Solution

If the pattern is as showed, then a regex option would be to create delimiter and make use of read.table

read.table(text = gsub('"', '', gsub('("[^,"]+,)(*SKIP)(*FAIL)|,',
   '\n', trimws(gsub(",{2,}", ",", str1), whitespace = ","), perl = TRUE)), 
    header = FALSE, fill = TRUE, sep = "\n")

-output

                V1
1            ABCDE
2 January 10, 2010
3                F
4               GH
5    March 9, 2009

Or with scan

data.frame(V1 = setdiff(scan(text = str1, sep = ",",
    what = character()), ""))

-output

              V1
1            ABCDE
2 January 10, 2010
3                F
4               GH
5    March 9, 2009

data

str1 <- "ABCDE,\"January 10, 2010\",F,,,,GH,\"March 9, 2009\",,,"