[R] save a list as a matrix

[Robert Ruser]

Hello,
Let's assume that one has a list:
my.list <- list(a=c(1,2,3,4),b=4,c=c(1:7))

I want to save my.list as a matrix in .txt file. Because of  different
length we can put NA or 0.
Effect (row.names a, b and c are not necessary)

a 1 2 3 4 0 0 0
b 4 0 0 0 0 0 0
c 1 2 3 4 5 6 7

How to do it?
Thank you.
Robert