Re: Programming style: postfix/prefix vs. functional

*To*: mathgroup at smc.vnet.net*Subject*: [mg70597] Re: Programming style: postfix/prefix vs. functional*From*: dimmechan at yahoo.com*Date*: Sat, 21 Oct 2006 05:13:28 -0400 (EDT)*References*: <eha5kn$b82$1@smc.vnet.net>

For a newcomer, as you said you are, I would suggest to use the complete name of the higher order built-in functions Map, Apply, MapAll. You should also use the /. and //. notations. Also you can write your code containg Map, Apply etc and converting to InputForm to get it with compact notation. This can be done by selecting the Cells, and then press simultaneously Shift+Ctrl+I. Some examples follow: Here is a user defined function that mofifies slightly the Plot function in order to deal with periodic discontinuus functions like Tan[x]. plotDisc[f_, {x_, a_, b_, c_}, opts___] := Show[Map[Plot[f, {x, Part[#, 1], Part[#, 2]}, opts,DisplayFunction -> Identity] &, Partition[Range[a, b, c],2, 1]], DisplayFunction -> $DisplayFunction] Here is an example of application plotDisc[Tan[x], {x, 0, 8Pi, Pi/2}, PlotStyle -> Blue, Frame -> True, Axes -> False] (*plot to be displayed*) Here is the same function after it was converted to InputForm plotDisc[f_, {x_, a_, b_, c_}, opts___] := Show[(Plot[f, {x, #1[[1]], #1[[2]]}, opts, DisplayFunction -> Identity] & ) /@ Partition[Range[a, b, c], 2, 1], DisplayFunction -> $DisplayFunction] Here is another user defined function that demonstrates the used ploints by the Plot algorithm and as well draw vertical lines connected them to horizontal axis. plotAlgor[f_, {x_, a_, b_}, opts___] := Show[ff = Plot[ f, {x, a, b}, opts, DisplayFunction -> Identity], Map[ Graphics[{{Red, Line[{{First[#], 0}, #}]}, {Green, PointSize[0.018], Point[#]}}] &, Cases[ff, {z_? NumberQ, w_?NumberQ}, Infinity]], DisplayFunction -> $DisplayFunction] Here is an example of application plotAlgor[x, {x, 0, 2Pi}, PlotStyle -> Blue]; plotAlgor[Sin[x], {x, 0, 2Pi}, PlotStyle -> Blue]; (*plots to be displayed*) and here is the same function converted in InputForm plotAlgor[f_, {x_, a_, b_}, opts___] := Show[ff = Plot[f, {x, a, b}, opts, DisplayFunction -> Identity], (Graphics[{{Red, Line[{{First[#1], 0}, #1}]}, {Green, PointSize[0.018], Point[#1]}}] & ) /@ Cases[ff, {(z_)?NumberQ, (w_)?NumberQ}, Infinity], DisplayFunction -> $DisplayFunction] See also the following ReplaceAll[log[a b c d],log[x_ y_]\[Rule]log[x]+log[y]] log[a]+log[b c d] The same expression in InputForm log[a*b*c*d] /. log[(x_)*(y_)] -> log[x] + log[y] log[a] + log[b*c*d] ReplaceRepeated[log[a b c d],log[x_ y_]\[Rule]log[x]+log[y]] log[a]+log[b]+log[c]+log[d] The same expression in InputForm log[a*b*c*d] //. log[(x_)*(y_)] -> log[x] + log[y] log[a] + log[b] + log[c] + log[d] Following Ted Esrek's advice (see http://www.verbeia.com/mathematica/tips/Tricks.html) I suggest that users in your position get a copy of The Mathematica Book and read sections 1.0 through 1.10, sections 2.1 through 2.4 (260 pages of light reading). Here are also some other links for introduction to Mathematica programming http://library.wolfram.com/infocenter/TechNotes/Mathematica/ http://library.wolfram.com/infocenter/MathSource/5216/ Lastlly I highly recomend you two books Introduction to Programming with Mathematica, Third Edition (by Wellin, Gaylord and Kamin) Mastering Mathematica: Programming Methods and Applications, Second Edition (by John W. Gray) Regards Dimitris Will Robertson wrote: > Hello, > > As a newcomer to Mathematica, I'm a little unsure on what "good style" > would be in this programming language. I notice that several functions > have prefix and postfix notations such as //. for ReplaceRepeated, /@ > for Map, and so on. > > Clearly using these forms makes the code more compact, but sacrifices > some level of readability. Are there guidelines or suggestions that > have built up over the years of whether these are "good" or "bad" to > use? > > If it's simply personal preference, what do you like to use? > -- > Many thanks, > Will Robertson