If your objective is to convert your string to a list of lists, you could do that in JSL. Here are two approaches:
// Given this string:
a = {"1.2, 2.3, 3.4", "5.6, 6.7, 7.8"};
// Return data like { {1.2, 2.3, 3.4} , {5.6, 6.7, 7.8} }
// Parse things apart
new_list = {};
m = 0;
for (i = 1, i <= nitems(a), i++,
one_list = words(a[i], ", ");
for (k = 1, k <= nitems(one_list), k++,
one_list[k] = num(one_list[k]);
);
m++;
new_list[m] = one_list;
);
print(new_list);
// Use matrix operators
exec_string = "new_mat = matrix({";
for (i = 1, i <= nitems(a), i++,
if (i == 1,
exec_string = exec_string || "{" || a[i] || "}";
,
exec_string = exec_string || ", {" || a[i] || "}";
);
);
exec_string = exec_string || "})";
eval(parse(exec_string));
print(new_mat);
The first one returns:
{{1.2, 2.3, 3.4}, {5.6, 6.7, 7.8}}
The second one returns a matrix:
[1.2 2.3 3.4, 5.6 6.7 7.8]