On Apr 20, 11:04 pm, per <perfr...@gmail.com> wrote: > On Apr 20, 11:08 pm, Steven D'Aprano > > > > <ste...@remove.this.cybersource.com.au> wrote: > > On Mon, 20 Apr 2009 11:39:35 -0700, per wrote: > > > hi all, > > > > i am generating a list of random tuples of numbers between 0 and 1 using > > > the rand() function, as follows: > > > > for i in range(0, n): > > > rand_tuple = (rand(), rand(), rand()) mylist.append(rand_tuple) > > > > when i generate this list, some of the random tuples might be very close > > > to each other, numerically. for example, i might get: > > [...] > > > how can i maximize the amount of "numeric distance" between the elements > > > of > > > this list, but still make sure that all the tuples have numbers strictly > > > between 0 and 1 (inclusive)? > > > Well, the only way to *maximise* the distance between the elements is to > > set them to (0.0, 0.5, 1.0). > > > > in other words i want the list of random numbers to be arbitrarily > > > different (which is why i am using rand()) but as different from other > > > tuples in the list as possible. > > > That means that the numbers you are generating will no longer be > > uniformly distributed, they will be biased. That's okay, but you need to > > describe *how* you want them biased. What precisely do you mean by > > "maximizing the distance"? > > > For example, here's one strategy: you need three random numbers, so > > divide the complete range 0-1 into three: generate three random numbers > > between 0 and 1/3.0, called x, y, z, and return [x, 1/3.0 + y, 2/3.0 + z]. > > > You might even decide to shuffle the list before returning them. > > > But note that you might still happen to get (say) [0.332, 0.334, 0.668] > > or similar. That's the thing with randomness. > > > -- > > Steven > > i realize my example in the original post was misleading. i dont want > to maximize the difference between individual members of a single > tuple -- i want to maximize the difference between distinct tuples. in > other words, it's ok to have (.332, .334, .38), as long as the other > tuple is, say, (.52, .6, .9) which is very difference from (.332, . > 334, .38). i want the member of a given tuple to be arbitrary, e.g. > something like (rand(), rand(), rand()) but that the tuples be very > different from each other. > > to be more formal by very different, i would be happy if they were > maximally distant in ordinary euclidean space... so if you just plot > the 3-tuples on x, y, z i want them to all be very different from each > other. i realize this is obviously biased and that the tuples are not > uniformly distributed -- that's exactly what i want... > > any ideas on how to go about this? > > thank you.
Two ideas. One, start with a square grid and jitter the individual points by a small random amount. Two, start with one point, and move from it by a random large distance: a2= a1+ .5+ rand( ), then %1. -- http://mail.python.org/mailman/listinfo/python-list
