Re: compact notation for NonCommutativeMultiply that supports cut and paste

*To*: mathgroup at smc.vnet.net*Subject*: [mg127727] Re: compact notation for NonCommutativeMultiply that supports cut and paste*From*: Tobias Hagge <tobiashagge at gmail.com>*Date*: Fri, 17 Aug 2012 03:43:44 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net*References*: <8525141.75636.1344674234471.JavaMail.root@m06> <k07hjo$cu8$1@smc.vnet.net>

David, thank you for your interesting solution. It does not allow copy/pasting of just part of a noncommutative product, which is a feature for some applications, but not quite what I need. After some experimentation I was able to find two ways to accomplish more precisely what I was looking for, which I'm posting below. Contrary to what I wrote (sorry), what I really want is SMALL (rather than no) spaces between the symbols, just like Times. I ran into these problems: 1) Executing this: << Notation` InfixNotation[ParsedBoxWrapper["foo"], NonCommutativeMultiply] NonCommutativeMultiply[a, b, c] and then copy/pasting the output gives "afoobfoo c". 2) Evaluating this: << Notation` Unprotect[NonCommutativeMultiply]; InfixNotation[ParsedBoxWrapper["\[Null]"], NonCommutativeMultiply]; NonCommutativeMultiply /: MakeBoxes[NonCommutativeMultiply[x__], StandardForm] := RowBox[Riffle[(MakeBoxes[#, StandardForm]) & /@ {x}, ConstantArray[ "\[InvisibleSpace]\[Null]\[InvisibleSpace]", Length[{x}] - 1]]]; NonCommutativeMultiply[a,b,c] and then copy/pasting gives input which evaluates correctly, however the spacing of output before copy/pasting still does not match the spacing after. For whatever reason, the following code does not produce the problematic whitespace. It gives a StandardForm output for NonCommutativeMultiply which looks like times, but copy/pastes to a form which evaluates as NonCommutativeMultiply. Unprotect[NonCommutativeMultiply]; InfixNotation[ParsedBoxWrapper["\[Null]"], NonCommutativeMultiply]; NonCommutativeMultiply /: MakeBoxes[NonCommutativeMultiply[x__], StandardForm] := RowBox[Flatten[ Riffle[(MakeBoxes[#, StandardForm]) & /@ {x}, ConstantArray[{"\[VeryThinSpace]", "\[Null]", "\[VeryThinSpace]"}, Length[{x}] - 1]] , 1] ]; \[VeryThinSpace] can be replaced with \[InvisibleSpace] if no spacing between factors is desired. I tried replacing \[Null] with "|" (to get something like your notation), but unfortunately, replacing \[VeryThinSpace] with \[NegativeVeryThinSpace] causes the bad whitespace to reoccur, so this code won't give a notation like yours which is as compact. A second solution is: InfixNotation[ParsedBoxWrapper["\[InvisibleApplication]"], NonCommutativeMultiply] It is simpler but has two slight disadvantages: 1) Invisible function application no longer works. 2) When copy/pasting part of a long product, there is no visible indication whether the end of the selection is a symbol or the noncommutative operator. Best, Tobias On Sunday, August 12, 2012 1:14:16 AM UTC-5, djmpark wrote: > I think you are saying that you don't like the x**y**z space taking infix > > operator of NonComutativeMultiple and want something more compact because of > > long multiplication sequences. I think it is a bit confusing to have no > > infix separator (Is every argument guaranteed to be a single character > > symbol?). The following uses a Vertical line and negative spaces to make a > > pretty compact form. > > > > Unprotect[NonCommutativeMultiply]; > > NonCommutativeMultiply /: > > MakeBoxes[NonCommutativeMultiply[x__ /; Length[{x}] > 1], > > form : (StandardForm | TraditionalForm)] := > > Module[{displayFunc, interpretationFunc, work1, work2, work3, > > n = Length[{x}], f}, > > > > work1 = > > Riffle[Table[Slot[i], {i, n}], > > RowBox[{"\[NegativeThinSpace]", "\[NegativeMediumSpace]", "|", > > "\[NegativeMediumSpace]", "\[NegativeThinSpace]"}]]; > > work2 = RowBox@work1; > > displayFunc = (Evaluate@work2) &; > > > > work3 = Riffle[Table[Slot[i], {i, n}], ","]; > > interpretationFunc = > > f[(RowBox[{"NonCommutativeMultiply", "[", Sequence @@ work3, > > "]"}])] /. f -> Function; > > > > TemplateBox[MakeBoxes[#, form] & /@ {x}, "NonCommutativeMultiply", > > DisplayFunction -> displayFunc, > > InterpretationFunction -> interpretationFunc] > > ] > > > > NonCommutativeMultiply[a, b, T, dd, F] > > % // FullForm > > % // InputForm > > > > TemplateBox is an undocumented, but rather nifty construction, that I got > > from WRI support some time ago. It can be copied and pasted. You can edit > > the variables but not other parts of the expression. Someone from WRI might > > give a neater formulation of this. > > > > > > David Park > > > > > From: tobiashagge > > > Hello, > > > > I am doing some group theory computations that have output of the form > > > > := NonCommutativeMultiply[very-long-sequence-of-letters] > > > > I want the StandardForm output to display as a string of symbols without > > spaces, just like the output of Times. I want to be able to copy and paste > > that output into an input line and have it be correctly interpreted. > > Finally, I want "a b" to evaluate as Times[a,b]. > > > > I decided to define the null character as an operator, piecing together bits > > of code from the internet. > > > > Unprotect[NonCommutativeMultiply]; > > InfixNotation[ParsedBoxWrapper["\[Null]"], NonCommutativeMultiply]; > > > > > > I'm having two issues: > > 1) The special characters are not visible in the notebook, which makes the > > code a bit hard to read. > > 2) Letters appear spaced apart in the output. If you copy and paste the > > output, the spacing disappears (so pushing the letters together in the > > output using negative space will make copy/paste awkward). > > > > Using AlignmentMarker instead of Null fixes the spacing issue. However, for > > reasons I do not understand, the InfixNotation command does not work in this > > case. > > > > Any help or helpful advice is appreciated. > > > > Best, > > Tobias