Re: [Tutor] lottery problem (Was Re: (no subject))
Adam Jensen wrote: Side note: if one were to only import specific functions from a module, would the load time and memory consumption be smaller? Example, is: from random import randint, seed smaller and faster than: import random Basically from random import randint, seed is equivalent to import random randint = random.randint seed = random.seed del random From that you can deduce that the whole random module is loaded into memory in both cases. A small speed advantage may be caused when the attribute lookup is avoided in a tight loop $ python3 -m timeit -s 'import random' 'random.randint' 1000 loops, best of 3: 0.0925 usec per loop $ python3 -m timeit -s 'from random import randint' 'randint' 1000 loops, best of 3: 0.0356 usec per loop but the actual randint() function call is so heavy that this speedup is lost in the noise when you actually invoke the function: $ python3 -m timeit -s 'from random import randint' 'randint(0, 42)' 10 loops, best of 3: 3.73 usec per loop $ python3 -m timeit -s 'import random' 'random.randint(0, 42)' 10 loops, best of 3: 3.82 usec per loop Side side note: since 'i' isn't being used, is there a way to loop (within the list comprehension) without the 'i'? For example, to generate three random numbers: [randint(1,10) for i in range(3)] # This works. [randint(1,10) for range(3)] # This does not work. No, but in numpy you can express it directly numpy.random.randint(1, 10, 3) or -- if you go back to the original problem -- with some effort: N = 3 numpy.random.randint(1, 10, N) + numpy.arange(0, N*10, 10) array([ 5, 11, 27]) In return the latter is likely significantly more efficient for large N than the generic list comprehension. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] lottery problem (Was Re: (no subject))
On Fri, 19 Dec 2014 10:32:15 +0100 Peter Otten __pete...@web.de wrote: Basically from random import randint, seed is equivalent to import random randint = random.randint seed = random.seed del random From that you can deduce that the whole random module is loaded into memory in both cases. A small speed advantage may be caused when the attribute lookup is avoided in a tight loop Thanks for the clarification, that's really helpful. So I guess the import style is more about name space management than controlling the details of what gets loaded... or -- if you go back to the original problem -- with some effort: N = 3 numpy.random.randint(1, 10, N) + numpy.arange(0, N*10, 10) array([ 5, 11, 27]) In return the latter is likely significantly more efficient for large N than the generic list comprehension. Ha! That's fun. Seven seems to be a magic number in the original problem, so maybe a little tweak: import numpy as np N=7 (np.random.randint(1,N,N) + np.arange(0,N*N,N)).tolist() ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
[Tutor] lottery problem (Was Re: (no subject))
On 18/12/14 21:10, Abdullahi Farah Mohamud wrote:
hello i need help with a program and i dont understand what is wrong
Please always add a meaningful subject line.
when the computers asks the user if he would like to go again
and the user says yes, it asks for the number of lines
and then if the user clicks 3 it will only give
me one line.
import random
abz = 0
lines = int(input('How many lines would you like?'))
loop = lines
if lines 7:
You might want to check fpor negative numbers too
or you will loop forever.
print('Too many lines saaxib')
exit()
else:
print()
while lines != 0:
line1 = random.randint (1,7)
line2 = random.randint (8,14)
line3 = random.randint (15,21)
line4 = random.randint (22,28)
line5 = random.randint (29,35)
line6 = random.randint (36,42)
line7 = random.randint (43,49)
lines = lines - 1
print(line1, line2, line3, line4, line5, line6,line7)
Down to here basically works. But...
You could have used a list instead of all the
individual variables
line[0] = ...
line[1] = ...
But then you could get clever and use a loop:
while lines != 0:
start = 1
period = 7
for lineNum in range(7):
line[lineNum] = random(start,period)
start += period
period += period
print (*line)
lines -=1
while abz == 0:
again = input('Would you like to go again?')
if again == 'yes':
lines = int(input('How many lines would you like?'))
line1 = random.randint (1,7)
Notice this is outside the if statement so will execute
regardless of the answer.
But unlike the equivalent section above it is NOT in a
while loop so will only execute once per question.
Which is what you were seeing.
line2 = random.randint (8,14)
line3 = random.randint (15,21)
line4 = random.randint (22,28)
line5 = random.randint (29,35)
line6 = random.randint (36,42)
line7 = random.randint (43,49)
lines = lines - 1
print(line1, line2, line3, line4, line5, line6,line7)
Since you are duplicating code you could put it in a function - have you
seen functions yet?
def getLine(start=1, period=7):
line = []
for lineNum in range(7):
line[lineNum] = random(start,period)
start += period
period += period
return line
then the while loop becomes:
while lines != 0:
line = getLine()
print(*line)
lines -= 1
if again == 'no':
print('Okay the program is finished saaxib')
exit()
HTH
--
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos
___
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Re: [Tutor] lottery problem (Was Re: (no subject))
On Fri, 19 Dec 2014 00:55:49 + Alan Gauld alan.ga...@btinternet.com wrote: You could have used a list instead of all the individual variables line[0] = ... line[1] = ... But then you could get clever and use a loop: while lines != 0: start = 1 period = 7 for lineNum in range(7): line[lineNum] = random(start,period) start += period period += period print (*line) lines -=1 A list comprehension might be fun. https://docs.python.org/3.4/tutorial/datastructures.html#list-comprehensions For example: [random.randint(x,x+6) for x in range(1,50,7)] [4, 9, 15, 27, 33, 36, 49] And to build the 'lines' list (although, this is getting rather ugly): lines = [[random.randint(x,x+6) for x in range(1,50,7)] for i in range(7)] lines [[2, 13, 18, 27, 35, 37, 47], [1, 11, 21, 24, 34, 37, 49], [7, 12, 16, 24, 29, 36, 44], [4, 9, 16, 22, 32, 37, 46], [2, 13, 20, 22, 29, 40, 46], [7, 14, 19, 26, 35, 42, 43], [4, 12, 16, 22, 34, 40, 46]] It might also be a good idea to execute random.seed() before calling randint() - https://docs.python.org/3.4/library/random.html#random.seed ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] lottery problem (Was Re: (no subject))
On Thu, 18 Dec 2014 20:27:03 -0500 Adam Jensen han...@riseup.net wrote: And to build the 'lines' list (although, this is getting rather ugly): lines = [[random.randint(x,x+6) for x in range(1,50,7)] for i in range(7)] Oops, in the context of the original program this might make more sense if written as: data = [[random.randint(x,x+6) for x in range(1,50,7)] for i in range(lines)] Side note: if one were to only import specific functions from a module, would the load time and memory consumption be smaller? Example, is: from random import randint, seed smaller and faster than: import random Side side note: since 'i' isn't being used, is there a way to loop (within the list comprehension) without the 'i'? For example, to generate three random numbers: [randint(1,10) for i in range(3)] # This works. [randint(1,10) for range(3)] # This does not work. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
