Velocity Reviews > Hpw make lists that are easy to sort.

# Hpw make lists that are easy to sort.

Anton Vredegoor
Guest
Posts: n/a

 03-31-2007
Paul Rubin wrote:

> Oh, I see what you mean. I don't see an obvious faster way to do it
> and I don't have the feeling that one necessarily exists. As someone
> mentioned, you could do an n-way merge, which at least avoids using
> quadratic memory. Here's a version using Frederik Lundh's trick of
> representing a lazy list as its head plus the generator for the tail:

That's a beautiful trick! I was just exploring some idea about
traversing the matrix starting from the upper left and ending at the
lower right by forming some kind of wave like front line. It's currently
very slow but I hope it can be polished a bit.

Also I was trying to figure out if it could have any advantage over the
straight row by row merge, but now that these lazy rows have appeared
the field has changed a lot

def typewriter(L,R):
Z = [0] * len(R)
M = [(L[0]+R[0],0)]
while M:
val,k = min(M)
yield val
Z[k] += 1
M = []
for k,x in enumerate(Z):
if x < len(R):
M.append((L[k]+R[x],k))
if not x:
break

A.