Nested List Doesn't Work Properly

import re def get_number(element): re_number = re.match('(\d+\.?\d*)', element) if re_number: return float(re_number.group(1)) else: return 1.0 def ge

Solution 1:

I think the problem is the assignment equation = eqn. Since eqn is a list, it is a mutable and thus passed as a reference, when you assign a mutable, the variable actually contains a pointer to that object. This means that equation and eqn are the same list.

You should

from copyimport deepcopy
equation = deepcopy(eqn)

You need deepcopy instead of copy because you have a list of lists, also the inner list needs to be copied.

Solution 2:

This line:

equation=eqn

doesn't do what you think it does. Try this instead:

importcopy
equation=copy.deepcopy(eqn)

Python assignment isn't a copy operation, but rather a binding operation. The line you have means "bind the name equation to the same object to which eqn is currently bound."

Your algorithm requires that equation and eqn are distinct objects.