<[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] >I am trying to write some code that will take a list of functional > expressions, and order them so that those with primitive terms appear > at the beginning of the list and those that are defined by other terms > appear last. > > eg: > getSortedEquations(['b = w + z','a = z - y','w = 2*z + v','z = e + > f','y = p + l']) = > ['w = 2*z + v', 'z = e + f', 'y = p + l', 'b = w + z', 'a = z - y'] > > It is easy enough to tokenise each of the equations and produce a list > like: > ['b', ['w','z']], ['a': ['z','y']], ['w':'z','v'] , ['z', ['e','f']], > ['y',['p','l']] > > But I'd like to find an algorithm that can handle the sorting problem. > > So I suspect that this is a common problem for those familiar with > partially ordered sets or directed graphs.
Right. > I'm wondering if anyone else > is familiar with this problem and knows an efficient algorithm that > will solve it. It would be good if any such algorithm would be able to > check for circular definitions in the input. Read http://en.wikipedia.org/wiki/Topological_sorting or just search for "topological sorting" on the net. Regards, Christian -- http://mail.python.org/mailman/listinfo/python-list
