Re: Python code for testing well parenthesized expression
> Don't you want to just test that the number of "("s equals the number of
> ")"s or am I missing the point?
I had this idea too, but there is additional requirement that any
beginning must have greater or equal number of '(' than ')'.
--
Adrian
--
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Re: Python code for testing well parenthesized expression
Strings are immutable, so your method of slicing one letter at time
will be building lots of them. That shouldn't hurt you here, but it
will when you hit a bigger problem. In the i() there should be "return
op == 0" on the end.
def well(expr):
mapping = {'(':1, ')':-1}
count = 0
for s in expr:
if s in mapping:
count += mapping[s]
if s < 0:
return False
return count == 0
def test_well():
examples = [
('zx4er(1(er(Yy)ol)ol)ik', True),
('x(x)x(x(x)xx(xx(x)x(x(x)xx)())x(x(x)xx)()x)()',
True),
('a(ty(y(y(bn)))lokl)kl', True),
('xc(er(tgy(rf(yh)()uj)ki))', True),
('e', True),
('rf(tgt)juj)jkik(jun)', False),
('zx(4er(1(er(Yy)ol)ol)ik', False),
]
for expr, expected in examples:
assert well(expr) == expected
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Re: older pythons
The recommended Debian way is update-alternatives. I find it a bit unintuitive, so I have to read through the documentation every time I use it, but it should be able link a chosen version of python to /usr/ bin/python. I don't know if it's set up by default, I have only one version installed. -- Adrian -- http://mail.python.org/mailman/listinfo/python-list
Re: modifying a list element from a function
Could you explain your high level goal for this? It looks like a very wicked way of doing things. Have You tried to read the list methods' documentation? Maybe there you find something you need (like list.index)? -- Adrian -- http://mail.python.org/mailman/listinfo/python-list
