Cristian.Codorean a écrit : > I was just reading a "Python Speed/Performance Tips" article on the > Python wiki > http://wiki.python.org/moin/PythonSpeed/PerformanceTips > and I got to the part that talks about string concatenation and that it > is faster when using join instead of += because of strings being > immutable.
This is somewhat obsolete. String concatenation have been subject to some optimization since 2.3.x (IIRC - else please someone correct me). NB: this is only true for CPython. But the "".join() idiom is, well, still idiomatic... > So I have tried it: > > from time import time > t=time() > > s='almfklasmfkmaskmkmasfkmkqemkmqeqw' > for x in range(40): > #s+= s[len(s)/2:] > s="".join((s,s[len(s)/2:])) Lol... I'm afraid you didn't get the idiom right. The point is to avoid useless allocations in the loop body. The idiom is: buf = [] for x in range(42): buf.append(s) s = "".join(buf) > print 'duration', time() - t timeit may be a better choice for microbenchmarks. -- http://mail.python.org/mailman/listinfo/python-list
