Here is how to do short timing tests using the timeit module from the
command line on windows. (C> is the prompt.
C> python -m timeit -s "import random" random.randint(1, 100)
or
C> python -m timeit -s "import random" int(1 + random.random()*99)
The above may be easier for short code fragments like the ones you were
looking at.
Richard
----- Original Message -----
From: "Jacob Kruger" <jacob@xxxxxxxxxxxxx>
To: <program-l@xxxxxxxxxxxxx>
Sent: Monday, October 01, 2012 1:26 PM
Subject: [program-l] Re: Python list access speeds
Ok, you were right - just did something similar again, and difference was:
It took 0.167999982834 seconds to do randInt 100000 times
It took 0.0449998378754 seconds to do random and convert output 100000
times
Here's the code:
#start code
import random, time
tInt = time.time()
for I in range(1, 100000):
iRand = random.randint(1, 100)
print "It took " + str(time.time() - tInt) + " seconds to do randInt
100000
times"
tRand = time.time()
for I in range(1, 100000):
fRand = random.random()
iRand = int(fRand * 100)
print "It took " + str(time.time() - tRand) + " seconds to do random and
convert output 100000 times"
#end code
Jacob Kruger
Blind Biker
Skype: BlindZA
'...fate had broken his body, but not his spirit...'
----- Original Message -----
From: "R Dinger" <rrdinger@xxxxxxxxxx>
To: <program-l@xxxxxxxxxxxxx>
Sent: Monday, October 01, 2012 4:42 PM
Subject: [program-l] Re: Python list access speeds
Regarding your random tests: reducing time from 7 seconds to 2.7 is still
2.59 times faster and that could be significant.
I vaguely recall your test, but I thought it was much closer.
Richard
----- Original Message -----
From: "Jacob Kruger" <jacob@xxxxxxxxxxxxx>
To: <program-l@xxxxxxxxxxxxx>
Sent: Sunday, September 30, 2012 9:36 PM
Subject: [program-l] Re: Python list access speeds
Reminds me of a test I did - put together two loops where used either
random.random() and converted the result to a number ranging from 1 to
100
sort of manually, and then did the same loop, but using random.randint(1,
100), and got them to both operate like 100000 times, and it was actually
slightly quicker to just use random.random(), but anyway - think
difference
was like 2.7 seconds, compared to like 7 seconds.
Stay well
Jacob Kruger
Blind Biker
Skype: BlindZA
'...fate had broken his body, but not his spirit...'
----- Original Message -----
From: "R Dinger" <rrdinger@xxxxxxxxxx>
To: "programming" <program-l@xxxxxxxxxxxxx>
Sent: Monday, October 01, 2012 1:01 AM
Subject: [program-l] Python list access speeds
I got to thinking about list access speeds when reading replies to Al's
iterator reset question last week, so I decided to do some testing with
the
timeit module. I tested access by subscript and by direct iteration.
I used the following setup code (a list of 500 random numbers) for all
the
tests. The time to execute the setup code is not included in the timing
tests.
setup = """
from random import random
valList = []
for i in xrange(500):
valList.append(random())
"""
The following code fragments were tested each running the loop 1 million
times.
stmt1 = """
for i in range(len(valList)):
v = valList[i]
"""
time: 8.01 sec
stmt2 = """
for i in xrange(len(valList)):
v = valList[i]
"""
time: 7.43 sec
stmt3 = """
for v in valList:
pass
"""
time: 2.67 sec
stmt4 = """
for i, v in enumerate(valList):
pass
"""
time: 6.12 sec
So access by subscripting from a list generated by the range function is
the
slowest. In the second test using xrange (a generator) helped a little,
but
not much. The third test using direct iteration of the list is clearly
much
faster. Finally in the last test I used the enumerate object to
generate
the subscripts in case that was needed by the application in addition to
the
list value.
The timeit module is quite handy, but be careful it can be quite
addictive
and lead to late nights testing all sorts of code fragments.
Richard
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