[Tutor] Why does counting to 20 million stress my computer? (original) (raw)

Dick Moores rdm at rcblue.com
Sat Jul 17 05:17:50 CEST 2004

Danny Yoo wrote at 10:21 7/16/2004:

An alternative solution is to use a while-loop, something like:

### counter = 0 while counter < 10: print "counter is:", counter counter = counter + 1 ###

Using range() on large numbers is a common gotcha, so don't worry too much about not knowing about xrange(). There are a few things that work perfectly well on small things, but break down when the problem grows much larger; range() is one of those.

Thanks, Danny.

I found an egregious error in the spin.py I posted earlier. It had k being augmented inside the range() loop. I took this line out, used xrange() instead of range(), and for a speed comparison, added the loop you suggested as another way.

Here are some results:

integer: 1000000 (1,000,000) Counting.. 0 to 1000000 in 0.141 seconds! And now counting using a different loop.. 0 to 1000000 in 0.406 seconds!

integer: 10000000 (10,000,000) Counting.. 0 to 10000000 in 1.500 seconds! And now counting using a different loop.. 0 to 10000000 in 4.016 seconds!

integer: 50000000 (50,000,000) Counting.. 0 to 50000000 in 7.188 seconds! And now counting using a different loop.. 0 to 50000000 in 19.110 seconds!

integer: 100000000 (100,000,000) Counting.. 0 to 100000000 in 15.078 seconds! And now counting using a different loop.. 0 to 100000000 in 40.204 seconds!

integer: 1000000000 (1,000,000,000) Counting.. 0 to 1000000000 in 148.859 seconds! And now counting using a different loop.. 0 to 1000000000 in 397.484 seconds!

Here's some info on my Dell desktop (thanks to Belarc Advisor): 2.80 gigahertz Intel Pentium 4 8 kilobyte primary memory cache 512 kilobyte secondary memory cache

Bus Clock: 533 megahertz

512 Megabytes Installed Memory

======================================= #spin2.py

import time print """ Enter an integer to count to from zero. To quit, enter x or q. """

while True: # for exiting via ^C or ^D try: max = raw_input("integer: ") except (TypeError, EOFError): print "Bye." break if len(max) == 0: print "Hey, don't just hit Enter, type an integer first!" continue if max in ["q", "x"]: print "Bye." break try: max = int(max) + 1 except: print "That's not an integer!" continue print "Counting.." tStart = time.time() for k in xrange(max): pass tEnd = time.time() print "0 to %d in %.3f seconds!" % (k, (tEnd - tStart))

 print "And now counting using a different loop.."
 c = 0
 tStart = time.time()
 while c < max -1 :
     c += 1
 tEnd = time.time()
 print "0 to %d in %.3f seconds!" % (c, (tEnd - tStart))

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

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