Strange dimension change of a nested array after readline and sympify operation?

If I understand correctly, in Julia m = [[1,2],[3,4]] is a two-dimensional vector with each vector of two elements. And this fact won't change after the operation of sympify

ms = sympy.sympify(m)  size(ms)  

The output will still be (2,), as expected.

However, if I create a file test.txt with just one line [[1,2],[3,4]] and run

using SymPy  open("test.txt") do io      while ! eof(io)          m = readline(io)          println(m)          ms = sympy.sympify(m)          println(ms)      end  end  

The output will be

[[1,2],[3,4]]  Sym[1 2; 3 4]  

Namely, now ms suddenly changes to a two-by-two matrix! I really cannot understand this (since the dimension of m after readline stays to be (2,) as before). Could someone explain this for me?

https://stackoverflow.com/questions/66994043/strange-dimension-change-of-a-nested-array-after-readline-and-sympify-operation April 08, 2021 at 05:00AM