457,842 Members | 1,608 Online Need help? Post your question and get tips & solutions from a community of 457,842 IT Pros & Developers. It's quick & easy.

# Random Number Generation?

 P: n/a Hello All, I need some help with random number generation. What I need exactly is: To create a few thousand numbers, decimal and integers, between 5 and 90, and then to export them as a single column at a spreadsheet. I am newbie, I was not able to create decimals with the random modules of Python 2.3. Thanks, Dimos __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com Dec 11 '05 #1
4 Replies

 P: n/a Dimos wrote: Hello All, I need some help with random number generation. What I need exactly is: To create a few thousand numbers, decimal and integers, between 5 and 90, and then to export them as a single column at a spreadsheet. I am newbie, I was not able to create decimals with the random modules of Python 2.3. The random module lets you create floats and integers, not instances of class decimal.Decimal (surely not in 2.3, which didn't even HAVE a module decimal in its standard library!). If you want floats, the way to create a float with uniform distribution between 5 and 90 is to call random.uniform(5, 90). If you want 3000: r3k = [random.uniform(5, 90) for i in xrange(3000)] None of the 3k numbers will be integers, and it's unlikely that any of the 3k floats happens to have a fractional part that's exactly 0. If you do want integers as well as floats, you'll have to decide with what probability an integer must appear instead of a float, and do a second pass on r3k to enforce this. Alex Dec 11 '05 #2

 P: n/a Dimos wrote: Hello All, I need some help with random number generation. What I need exactly is: To create a few thousand numbers, decimal and integers, between 5 and 90, and then to export them as a single column at a spreadsheet. I am newbie, I was not able to create decimals with the random modules of Python 2.3. You use randint(a,b) to generate an integer between a and b. For real numbers, the function is random(). But that result is always between 0.0 and 1.0, so you have to make the range adjustment yourself. import random for i in range(10): print random.random()*85 + 5 20.2844473176 83.5690712033 77.3459998722 8.79906993754 53.3672450881 25.2609744882 19.8894951301 39.9794852838 43.4056977237 21.7770662903 Thanks, Dimos __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com Dec 11 '05 #3

 P: n/a On Sun, 11 Dec 2005 09:46:33 -0800 (PST), Dimos wrote: Hello All,I need some help with random number generation. What Ineed exactly is:To create a few thousand numbers, decimal andintegers, between 5 and 90,and then to export them as a single column at aspreadsheet.I am newbie, I was not able to create decimals withthe random modules ofPython 2.3. Others have mentioned random.random and, better for your use case, random.uniform, but I'm not sure what you mean by "decimal and integers". Theoretically, the chances of getting an integer from a uniformly random sample from an interval of real numbers is practically zero, and even allowing for IEEE 754 double representation, the realtive population of integers vs non-integers is pretty low. So what do you mean by "integer"? And what by "decimals"? If you just want an artificial sprinkling of exact integer values to happen some percentage of the time, you could do something like from random import uniform, random def urnmix(nnum=20, lo=5, hi=90, percentint=25): ... percentint /= 100. ... for _ in xrange(nnum): ... u = uniform(5, 90) ... if random()

 P: n/a bo**@oz.net (Bengt Richter) writes: Theoretically, the chances of getting an integer from a uniformly random sample from an interval of real numbers is practically zero, and even allowing for IEEE 754 double representation, Well, if we're going to be picky, the chances of getting a number with an IEEE 754 representation from a uniformly random sample from an interval of real numbers is practically zero. Of course, this is true for *any* finite subset of the reals (such as the set of numbers that have names that can be pronounced in the average human lifespan), and probably an infinite number of infinite subsets as well. But I tend to pick irrationals when asked to "pick a number between 1 and 10." So what do you mean by "integer"? And what by "decimals"? I think we should start by finding out what he means by "number", which is apparently a superset of both what he means by "integer" and "decimals". http://www.mired.org/home/mwm/ Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information. Dec 12 '05 #5

### This discussion thread is closed

Replies have been disabled for this discussion. 