RE: Pipes Inside Mathematica?

*To*: mathgroup at smc.vnet.net*Subject*: [mg45669] RE: [mg45659] Pipes Inside Mathematica?*From*: "David Park" <djmp at earthlink.net>*Date*: Sat, 17 Jan 2004 02:34:39 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

Harold, There was a question similar to this just a few days ago. {{5*Pi}, {13*E}} // IntegerPart // Table[0, Extract[#, 1] // Evaluate, Extract[#, 2] // Evaluate] & If you want to use a function that requires more than one argument after //, then use a pure function. The only extra problem in this case is that Table has the Attribute HoldAll so we also have to Evaluate the iterators. David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ From: Harold Noffke [mailto:Harold.Noffke at wpafb.af.mil] To: mathgroup at smc.vnet.net MathGroup: I think Mathematica would be a better programming language if it had a construct that allowed pipes (like Unix does). The //-mark comes close to facilitating this, but Mathematica needs a placeholder to denote "result from preceding //-mark". Here's a short example to illustrate what would be gained. In[1]:= m = 5*Pi // IntegerPart Out[1]= 15 In[2]:= n = 13*E // IntegerPart Out[2]= 35 In[3]:= Table[0, {m}, {n}] // MatrixForm Out[3]//MatrixForm= 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 > > 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 : : : : : : 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 > 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 What we would really like to write is the preceding computation as a pipeline, so that it looks something like this ... {{5*Pi},{13*E}} // IntegerPart // Table[0, Extract[<?>,1], Extract[<?>,2]] // MatrixForm The <?> symbol means, "I don't know what to put here" -- it's a placeholder for whatever Mathematica wants to use as "result from preceding //-mark". Maybe @ would make a good placeholder here, and what we would see on screen is ... {{5*Pi},{13*E}} // IntegerPart // Table[0, Extract[@,1], Extract[@,2]] // MatrixForm I think Mathematica will be a better programming language if it adopts some sort of pipe convention. Harold