[R] How to import variable length lists of lists into R from text file?

[Britt Anderson]

I will be collecting data where one of the fields may be of length
zero to some variable number of elements, along with other items of
fixed size.

As an illustration if mydata.dat is:

V1 V2   V3           V4             V5
1, 2.3, "Bob", {1.7,2.3,3.4}, 4.5
2, 3.4, "Carol", {}, 3.4
3, 2.2, "Ted", {1.0,2.5}, 3.5 ...
...

I want to be able to do something like mydata <-
read.csv("./mydata.dat") and have the field with curly braces live in
a single cell of the data frame as a potentially empty list of
floating point numbers. Is this possible? I am creating the text file
so I can put in whatever characters would be useful to facilitate this
operation. The curly braces are just for example purposes.

Thank you,
Britt Anderson