Rogério Brito wrote:
Hi, All.
I'm just getting my feet wet on Python and, just for starters, I'm
coding some elementary number theory algorithms (yes, I know that most
of them are already implemented as modules, but this is an exercise in
learning the language idioms).
As you can see from the code below, my background is in C, without too
much sophistication.
What I would like is to receive some criticism to my code to make it
more Python'esque and, possibly, use the resources of the computer in a
more efficient way (the algorithm implemented below is the Sieve of
Eratosthenes):
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#!/usr/bin/env python
n = int(raw_input())
a = [i for i in range(0,n+1)]
a[1] = 0 # not a prime
prime = 1 # last used prime
finished = False
while (not finished):
prime = prime + 1
# find new prime
while prime*prime <= n and a[prime] == 0:
prime += 1
# cross the composite numbers
if prime*prime <= n:
j = 2*prime
while j <= n:
a[j] = 0
j += prime
else:
finished = True
# print out the prime numbers
i = 2
while i <= n:
if a[i] != 0:
print a[i]
i += 1
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Thank you for any help in improving this program,
Your Python is actually pretty good - if Raymond Hettinger pronounces it
OK then few would dare to disagree.
As for your English, though, the word you sought was "Pythonic" (not
that you will ever find such a word in Webster's dictionary). To suggest
that your code is Pythonesque would mean you found it farcical or
ridiculous (like a Monty Python sketch), which it clearly is not.
Another wrinkle you might consider is simply printing the primes out as
they are generated rather than doing the printing in a separate loop,
though whether that approach would be preferable in "real life" would
depend on the application, of course.
regards
Steve
PS: I think either my mailer or yours has mangled the indentation.
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Steve Holden +1 571 484 6266 +1 800 494 3119
Holden Web LLC http://www.holdenweb.com/
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