How do you undo x = `a` if A is a list?

Moshe Zadka moshez at math.huji.ac.il
Fri Feb 11 22:14:34 CET 2000


On Fri, 11 Feb 2000, Trent Mick wrote:

> > Now how do I read that line in from a file and convert it from a
> > string to a
> > list?
> 
> Here is one way. Save your variable in the proper format to a Python module.
> Don't know if I would recommend it. As Skip et al. suggest, eval() and its
> kin are probably better.

One reason to do what you suggest is to use a pre-calculated table.

for example

def primes(n):
	# generate a list of all primes less then n
	pass

a = primes(10000)
f = open("primes.py", 'w')
f.write("a="+`a`)
f.close()

=========================

Then do "import primes" whenever you want a list of the primes less then
10000. It is *extremely* fast after the first time: it uses Python's
"marshal", which is heavily optimized.

--
Moshe Zadka <mzadka at geocities.com>. 
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