Re: Loop programming; how do i do this ???
- To: mathgroup at smc.vnet.net
- Subject: [mg96116] Re: Loop programming; how do i do this ???
- From: Peter Pein <petsie at dordos.net>
- Date: Thu, 5 Feb 2009 04:41:03 -0500 (EST)
- References: <gmbr29$igp$1@smc.vnet.net>
plzhlp schrieb: > I need to implement a function into my notebook but am having great difficulties even getting started (i'm new to mathematica and programming in general) > > The function accepts a 1d array (of variable length) of integers > > which will refer to a 2d array of constants, of which all need to be tested against eachother. > > for example: > > 1DArrayVar = {2, 4, 5} > > 2DArrayCon = { > {a1,b1,c1}, > {a2,b2,c2}, > {a3,b3,c3}, > {a4,b4,c4}, > {a5,b5,c5} > } > > Function[1DArrayVar] > > in this scenario will test: > > Do[ > Do[ > Do[ > > TEST[2DArrayCon[[2,x]],2DArrayCon[[4,y]],2DArrayCon[[5,z]]] > > , {x, Length[DArrayCon[[2]]] > , {y, Length[DArrayCon[[4]]] > , {z, Length[DArrayCon[[5]]] > > > So basically the problem is that i need a variable amount of nested loops, as the length of 1DArrayVar will always be unknown. > >>From some research on the internet i've learned a recursive algorithm might be the solution, but i am completely lost on how to start -- > > any tips would be really appreciated ! > Hi, I would use In[1]:= D1ArrayVar = {2, 4, 5}; D2ArrayCon = {{a1, b1, c1}, {a2, b2, c2}, {a3, b3, c3}, {a4, b4, c4}, {a5, b5, c5}}; In[3]:= Apply[TEST, Distribute[D2ArrayCon[[D1ArrayVar]], List], {1}] Out[3]= {TEST[a2, a4, a5], TEST[a2, a4, b5], TEST[a2, a4, c5], TEST[a2, b4, a5], TEST[a2, b4, b5], TEST[a2, b4, c5], TEST[a2, c4, a5], TEST[a2, c4, b5], TEST[a2, c4, c5], TEST[b2, a4, a5], TEST[b2, a4, b5], TEST[b2, a4, c5], TEST[b2, b4, a5], TEST[b2, b4, b5], TEST[b2, b4, c5], TEST[b2, c4, a5], TEST[b2, c4, b5], TEST[b2, c4, c5], TEST[c2, a4, a5], TEST[c2, a4, b5], TEST[c2, a4, c5], TEST[c2, b4, a5], TEST[c2, b4, b5], TEST[c2, b4, c5], TEST[c2, c4, a5], TEST[c2, c4, b5], TEST[c2, c4, c5]} or with a shorter list of indices: In[4]:= Apply[TEST, Distribute[D2ArrayCon[[{1, 4}]], List], {1}] Out[4]= {TEST[a1, a4], TEST[a1, b4], TEST[a1, c4], TEST[b1, a4], TEST[b1, b4], TEST[b1, c4], TEST[c1, a4], TEST[c1, b4], TEST[c1, c4]}