On 08/10/2016 11:54, Chris Angelico wrote:
On Sat, Oct 8, 2016 at 9:12 PM, BartC <b...@freeuk.com> wrote:
On 08/10/2016 11:03, Chris Angelico wrote:
On Sat, Oct 8, 2016 at 8:58 PM, meInvent bbird <jobmatt...@gmail.com>
wrote:
how to refactor nested for loop into smaller for loop assume each of them
independent?
because memory is not enough
for ii in range(1,2000):
for jj in range(1,2000):
for kk in range(1,2000):
print run(ii,jj,kk)
Since you're using Python 2, you could try xrange instead of range.
But it won't make a lot of difference. You're trying to call your run
function 8,000,000,000 times... that is a *lot* of function calls.
Consider a faster algorithm instead!
Printing even one character 8 billion times is likely to take quite a few
hours too.
The OP's code however is a good demonstration of how crazy Python's original
for-range loop was: you need to construct a list of N elements just to be
able to count to N. How many years was it until xrange was introduced?
Hardly matters in this case. The memory usage of a list of 2000 ints is:
sys.getsizeof(range(2000))
16072
2000 * sys.getsizeof(1999)
48000
About 64KB. Not overly significant.
Well, there'll be three lots. But it's true there won't be 8 billion
elements which is what I immediately thought when the OP said they'd run
out of memory. So perhaps something is going on inside run() to account
for it.
--
Bartc
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