http://code.activestate.com/recipes/tags/random_number-random/2012-08-07T15:35:23-07:00ActiveState Code Recipes2012-08-07T15:35:23-07:00Dale Lindemanhttp://code.activestate.com/recipes/users/4183096/http://code.activestate.com/recipes/578237-featureclassrandomizer/

<p style="color: grey"> Python recipe 578237 by <a href="/recipes/users/4183096/">Dale Lindeman</a> (<a href="/recipes/tags/randomization/">randomization</a>, <a href="/recipes/tags/random_number/">random_number</a>). </p> <p>Generates a randomized list of unique IDs and iteratively assigns values to features in a featureclass.</p>

2010-02-25T14:07:08-08:00Jayesh Shethhttp://code.activestate.com/recipes/users/4173165/http://code.activestate.com/recipes/577071-generate-an-alpha-numeric-password-salt/

<p style="color: grey"> PHP recipe 577071 by <a href="/recipes/users/4173165/">Jayesh Sheth</a> (<a href="/recipes/tags/md5/">md5</a>, <a href="/recipes/tags/password/">password</a>, <a href="/recipes/tags/random_number/">random_number</a>, <a href="/recipes/tags/salt/">salt</a>). </p> <p>Generate an alpha-numeric password salt (with a default of 32 characters)</p>

2008-11-16T15:05:51-08:00denishttp://code.activestate.com/recipes/users/4168005/http://code.activestate.com/recipes/576564-walkers-alias-method-for-random-objects-with-diffe/

<p style="color: grey"> Python recipe 576564 by <a href="/recipes/users/4168005/">denis</a> (<a href="/recipes/tags/random_number/">random_number</a>, <a href="/recipes/tags/walker_s_alias/">walker_s_alias</a>). </p> <p>an example, strings A B C or D with probabilities .1 .2 .3 .4 --</p> <pre class="prettyprint"><code>abcd = dict( A=1, D=4, C=3, B=2 ) # keys can be any immutables: 2d points, colors, atoms ... wrand = Walkerrandom( abcd.values(), abcd.keys() ) wrand.random() # each call -&gt; "A" "B" "C" or "D" # fast: 1 randint(), 1 uniform(), table lookup </code></pre>

2008-11-05T07:52:39-08:00Kaushik Ghosehttp://code.activestate.com/recipes/users/4166965/http://code.activestate.com/recipes/576556-generating-random-numbers-with-arbitrary-distribut/

<p style="color: grey"> Python recipe 576556 by <a href="/recipes/users/4166965/">Kaushik Ghose</a> (<a href="/recipes/tags/matplotlib/">matplotlib</a>, <a href="/recipes/tags/random_number/">random_number</a>). </p> <p>This is a class that allows you to set up an arbitrary probability distribution function and generate random numbers that follow that arbitrary distribution.</p>

2008-09-21T21:21:52-07:00Kaushik Ghosehttp://code.activestate.com/recipes/users/4166965/http://code.activestate.com/recipes/576512-generating-correlated-random-numbers/

<p style="color: grey"> Python recipe 576512 by <a href="/recipes/users/4166965/">Kaushik Ghose</a> (<a href="/recipes/tags/matplotlib/">matplotlib</a>, <a href="/recipes/tags/random_number/">random_number</a>). </p> <p>From this great <a href="http://www.sitmo.com/doc/Generating_Correlated_Random_Numbers">tutorial</a></p> <p>For two corelated variables, the formula is much as one would get from intuition about the meaning of correlation with some twist due to normalizing the standard deviation: $X_3 = \alpha X_1 + \sqrt{1-\alpha^2} X_2$ Where $X_1$ and $X_2$ are two independent random variables, and $\alpha$ is the coefficient of correlation between $X_1$ and $X_3$.</p> <p>In a more general sense: <br /> Let $C$ be the correlation matrix desired. Let $X_1, X_2..., X_N$ be $N$ independent random variables arranged in a row matrix $R = [X_1, X_2,....,X_N]$. Then $Q = RU$ where $U^TU = C$ gives us $N$ random variables $Q = [Y_1, Y_2, ..., Y_N]$ with the required property.</p>