Converting a list to a data frame

How does one convert a list into a data frame?

str(weight_chains)

List of 1

$ : 'mcmc' num [1:100000, 1:3] -105 -105 -105 -104 -103 ...

  ..- attr(*, "dimnames")=List of 2

  .. ..$ : NULL

  .. ..$ : chr [1:3] "a" "b" "s"

  ..- attr(*, "mcpar")= num [1:3] 1001 101000 1

- attr(*, "class")= chr "mcmc.list"

 

Such that ..

weight_chains



               a         b         s  

1     -104.72512 1.0141407  9.369227

2     -104.52297 1.0167432  9.131354

3     -104.72669 1.0139528  9.219877