newbie is looking for a customDistribution function

*To*: mathgroup at smc.vnet.net*Subject*: [mg50383] newbie is looking for a customDistribution function*From*: János <janos.lobb at yale.edu>*Date*: Wed, 1 Sep 2004 01:49:22 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Hi, I looked for it in the archives, but found none. I am looking for ways to create a custom distribution, which I can call as a function. Here is an example for illustration. Let's say I have a list created from a 4 elements alphabet {a,b,c,d}: In[1]:= lst={a,a,b,c,a,d,a,c,c,a} Out[1]= {a,a,b,c,a,d,a,c,c,a} Distribute gives me - thanks David Park - all the two element combinations of {a,b,c,d} In[11]:= twocombs=Distribute[Table[{a,b,c,d},{2}],List] Out[11]= {{a,a},{a,b},{a,c},{a,d},{b,a},{b,b},{b,c},{b,d},{c,a},{c,b},{c,c},{c,d} ,{ d,a},{d,b},{d,c},{d,d}} I can count the occurrence of an element of twocombs in lst with the following function: occuranceCount[x_List] := Count[Partition[lst, 2, 1], x] Mapping this function over twocombs gives me the number of occurances of elements of twocombs in lst: In[12]:= distro=Map[occuranceCount,twocombs] Out[12]= {1,1,1,1,0,0,1,0,2,0,1,0,1,0,0,0} It shows that for example {c,a} occurs twice, {d,a} occurs once and {d,c} or {d,d} never occur. Now, I would like to create a distribution function called twocombsLstDistribution which I could call and it would give me back elements of twocombs with the probability as they occur in distro, that is for on average I would get twice as much {c,a}s as {d,a}s and never get {d.c} or {d,d}. How can I craft that ? /Of course I need it for an arbitrary but finite length string lst over a fixed length alphabet {a,b,c,d,....} for k-length elements of kcombs, and it has to be super fast :). My real lst is between 30,000 and 70,000 element long over a four element alphabet and I am looking for k between 5 and a few hundred. / Thanks ahead, János ------------------------------------------------- People never lie so much as after a hunt, during a war or before an election - Otto von Bismarck -

**Follow-Ups**:**Re: Re: newbie is looking***From:*Tomas Garza <tgarza01@prodigy.net.mx>

**Re: newbie is looking for a customDistribution function***From:*DrBob <drbob@bigfoot.com>

**Re: newbie is looking for a customDistribution function***From:*Tomas Garza <tgarza01@prodigy.net.mx>