On Nov 16, 11:04 pm, Steven D'Aprano <[EMAIL PROTECTED] cybersource.com.au> wrote: > On Sun, 16 Nov 2008 02:41:03 -0800, John Machin wrote: > > On Nov 16, 9:31 pm, Steven D'Aprano <[EMAIL PROTECTED] > > cybersource.com.au> wrote: > >> On Sun, 16 Nov 2008 01:50:16 -0800, John Machin wrote: > >> > > def A(w, v, i,j): > >> > > if i == 0 or j == 0: return 0 > >> > > if w[i-1] > j: return A(w, v, i-1, j) if w[i-1] <= j: return > >> > > max(A(w,v, i-1, j), v[i-1] + > >> > > A(w,v, i-1, j - w[i-1])) > >> >> I am reading this blog > > >> >>http://20bits.com/articles/introduction-to-dynamic-programming/ > > >> > I suggest that you don't bother reading a blog written by somebody > >> > who (presumably consciously) keyed in that "if w[i-1] <= j: " above. > > >> That is a translation of standard terminology for a hybrid function. > >> Mathematics doesn't have an "else", so you write hybrid functions by > >> enumerating each branch as an if. > > > An else is not required. > > if w[i-1] > j: > > return A(w, v, i-1, j) > > return max(A(w,v, i-1, j), v[i-1] + A(w,v, i-1, j - w[i-1])) > > Which is also not valid terminology for hybrid functions.
I couldn't care less. It's valid and efficient (compared to the original) Python. > >> While it's not especially good Python technique, it's a perfectly > >> idiomatic mathematical expression, and shouldn't be the basis for > >> dismissing an entire blog. > > > He's meant to be writing Python code, not mathematical expressions. > > And he's written Python code. Perfectly valid Python code. Just because > it is not what you consider to be idiomatic Python code isn't a good > reason to dismiss his entire blog. > > What you've done is rather like me saying that because you failed to use > a colon after "required", and therefore haven't written what *I* consider > good English style, not only is your specific post best avoided, but > *all* your posts should be avoided. I trust you understand the logical > fallacy I would be making, which you have already made. Nothing to do with style. It was the screaming inefficiency of: if non_trivial_condition: return x if not non_trivial_condition: return y that fired me up. > http://en.wikipedia.org/wiki/Style_over_substance_fallacy Quoted Wikipedia -> instant disqualification -> you lose. Good night. -- http://mail.python.org/mailman/listinfo/python-list