The problem is not with len(), merely with the conversion from an int
to an Integer required in comparing len(results)<cota.
The following code is faster than either of your versions. Note that
'3r' is an int, whereas '3' is an Integer.
tri=pen=hex=dt=dp=dh=1r
results=[]
cota = 3r
while len(results)<cota:
if tri==pen==hex:
results.append(tri)
if tri<=pen and tri<=hex:
dt+=1r
tri+=dt
elif pen<=hex:
dp+=3r
pen+=dp
else:
dh+=4r
hex+=dh
print results
On Tue, Nov 23, 2010 at 3:00 AM, Pablo Angulo <pablo.ang...@uam.es> wrote:
> Hello:
> A colleague was working in code for a certain projecteuler problem,
> and found that using "len" of a list has a severe penalty on the sage
> notebook, which doesn't happen on either the sage or the python console.
> The two versions of the code below differ only in a call to the function
> len. In console, the penalty in performance is around 10%, but in the
> Sage notebook, it takes 3 times longer: the call to "len" costs doble
> time as the rest of the loop. Anyway, we've been getting weird results
> from time and its family lately (like CPU time longer than Wall time: is
> that ok?). This is tested on versions 4.6 and 4.4, on different
> architectures.
>
> Regards
>
> Version 1
>
> tri=pen=hex=dt=dp=dh=1
> results=[]
> cota = 3
> while len(results)<cota:
> if tri==pen==hex:
> results.append(tri)
> if tri<=pen and tri<=hex:
> dt+=1
> tri+=dt
> elif pen<=hex:
> dp+=3;
> pen+=dp
> else:
> dh+=4;
> hex+=dh
> print results
>
>
> Version 2
>
> cota = 3
> tri=pen=hex=dt=dp=dh=1
> results=[]
> n=0
> while n<cota:
> if tri==pen==hex:
> results.append(tri)
> n+=1
> if tri<=pen and tri<=hex:
> dt+=1
> tri+=dt
> elif pen<=hex:
> dp+=3;
> pen+=dp
> else:
> dh+=4;
> hex+=dh
> print results
>
> --
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