Store GAP REPL representation of expression in string












1














I have noticed that the representation that is displayed by the GAP REPL (read-evaluate-print loop) when an expression is evaluated sometimes differs from the result of printing that same expression, e.g.:



gap> x:=PartialPerm([1,2],[3,4]);

[1,3][2,4]

gap> Print(x);

PartialPerm( [1, 2], [3, 4] );


Is there some general way to obtain the former string representation outside of an interactive GAP session which will work for any expression? (Or, failing that, a way that works in the special case of partial permutations?)






gap







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    1














    I have noticed that the representation that is displayed by the GAP REPL (read-evaluate-print loop) when an expression is evaluated sometimes differs from the result of printing that same expression, e.g.:



    gap> x:=PartialPerm([1,2],[3,4]);
    
[1,3][2,4]
    
gap> Print(x);
    
PartialPerm( [1, 2], [3, 4] );


    Is there some general way to obtain the former string representation outside of an interactive GAP session which will work for any expression? (Or, failing that, a way that works in the special case of partial permutations?)






    gap







    share|cite|improve this question



























      1












      1








      1







      I have noticed that the representation that is displayed by the GAP REPL (read-evaluate-print loop) when an expression is evaluated sometimes differs from the result of printing that same expression, e.g.:



      gap> x:=PartialPerm([1,2],[3,4]);
      
[1,3][2,4]
      
gap> Print(x);
      
PartialPerm( [1, 2], [3, 4] );


      Is there some general way to obtain the former string representation outside of an interactive GAP session which will work for any expression? (Or, failing that, a way that works in the special case of partial permutations?)






      gap







      share|cite|improve this question















      I have noticed that the representation that is displayed by the GAP REPL (read-evaluate-print loop) when an expression is evaluated sometimes differs from the result of printing that same expression, e.g.:



      gap> x:=PartialPerm([1,2],[3,4]);
      
[1,3][2,4]
      
gap> Print(x);
      
PartialPerm( [1, 2], [3, 4] );


      Is there some general way to obtain the former string representation outside of an interactive GAP session which will work for any expression? (Or, failing that, a way that works in the special case of partial permutations?)






      gap




      gap






      share|cite|improve this question















      share|cite|improve this question













      share|cite|improve this question




      share|cite|improve this question








      edited yesterday









      Alexander Konovalov

      5,16221956




      5,16221956










      asked yesterday









      Peter

      1394




      1394






















          1 Answer
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          oldest

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          2














          GAP has operations DisplayString, ViewSrting and PrintString documented here. Usually, displaying an object produces a human-readable relatively complete and verbose output, viewing produces a short and concise output, and printing produces an output in a complete form which is GAP readable (if at all possible), such that reading the output into GAP produces an object which is equal to the original one.



          Depending on the type of the object, they may delegate to each other in the order specified here.



          In the example in question, we have



          gap> PrintString(x);
          
"PartialPerm( >[ 1, 2 ], <>[ 3, 4 ]<> )<"
          
gap> ViewString(x);
          
">[>1<,>3<<]>[>2<,>4<<]"
          
gap> DisplayString(x);
          
"<object>n"


          As you see, the output have additional control characters < (ASCII 1) and > (ASCII 2) that allow proper line breaks. The function StripLineBreakCharacters (see here) may be used to remove them:



          gap> StripLineBreakCharacters(PrintString(x));
          
"PartialPerm( [ 1, 2 ], [ 3, 4 ] )"
          
gap> StripLineBreakCharacters(ViewString(x));
          
"[1,3][2,4]"
          
gap> StripLineBreakCharacters(DisplayString(x));
          
"<object>n"


          There is also String (see here) which should approximate as closely as possible the character sequence you see if you print an object:



          gap> String(x);
          
"PartialPerm( [ 1, 2 ], [ 3, 4 ] )"


          Perhaps for partial permutations that's the best option.






          share|cite|improve this answer























          • Thanks, very helpful (although it feels like this shouldn't be this complicated but I guess that's on GAP).
            – Peter
            yesterday










          • There is also String - will update the answer now.
            – Alexander Konovalov
            yesterday











          Your Answer





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          1 Answer
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          1 Answer
          1






          active

          oldest

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          active

          oldest

          votes






          active

          oldest

          votes









          2














          GAP has operations DisplayString, ViewSrting and PrintString documented here. Usually, displaying an object produces a human-readable relatively complete and verbose output, viewing produces a short and concise output, and printing produces an output in a complete form which is GAP readable (if at all possible), such that reading the output into GAP produces an object which is equal to the original one.



          Depending on the type of the object, they may delegate to each other in the order specified here.



          In the example in question, we have



          gap> PrintString(x);
          
"PartialPerm( >[ 1, 2 ], <>[ 3, 4 ]<> )<"
          
gap> ViewString(x);
          
">[>1<,>3<<]>[>2<,>4<<]"
          
gap> DisplayString(x);
          
"<object>n"


          As you see, the output have additional control characters < (ASCII 1) and > (ASCII 2) that allow proper line breaks. The function StripLineBreakCharacters (see here) may be used to remove them:



          gap> StripLineBreakCharacters(PrintString(x));
          
"PartialPerm( [ 1, 2 ], [ 3, 4 ] )"
          
gap> StripLineBreakCharacters(ViewString(x));
          
"[1,3][2,4]"
          
gap> StripLineBreakCharacters(DisplayString(x));
          
"<object>n"


          There is also String (see here) which should approximate as closely as possible the character sequence you see if you print an object:



          gap> String(x);
          
"PartialPerm( [ 1, 2 ], [ 3, 4 ] )"


          Perhaps for partial permutations that's the best option.






          share|cite|improve this answer























          • Thanks, very helpful (although it feels like this shouldn't be this complicated but I guess that's on GAP).
            – Peter
            yesterday










          • There is also String - will update the answer now.
            – Alexander Konovalov
            yesterday
















          2














          GAP has operations DisplayString, ViewSrting and PrintString documented here. Usually, displaying an object produces a human-readable relatively complete and verbose output, viewing produces a short and concise output, and printing produces an output in a complete form which is GAP readable (if at all possible), such that reading the output into GAP produces an object which is equal to the original one.



          Depending on the type of the object, they may delegate to each other in the order specified here.



          In the example in question, we have



          gap> PrintString(x);
          
"PartialPerm( >[ 1, 2 ], <>[ 3, 4 ]<> )<"
          
gap> ViewString(x);
          
">[>1<,>3<<]>[>2<,>4<<]"
          
gap> DisplayString(x);
          
"<object>n"


          As you see, the output have additional control characters < (ASCII 1) and > (ASCII 2) that allow proper line breaks. The function StripLineBreakCharacters (see here) may be used to remove them:



          gap> StripLineBreakCharacters(PrintString(x));
          
"PartialPerm( [ 1, 2 ], [ 3, 4 ] )"
          
gap> StripLineBreakCharacters(ViewString(x));
          
"[1,3][2,4]"
          
gap> StripLineBreakCharacters(DisplayString(x));
          
"<object>n"


          There is also String (see here) which should approximate as closely as possible the character sequence you see if you print an object:



          gap> String(x);
          
"PartialPerm( [ 1, 2 ], [ 3, 4 ] )"


          Perhaps for partial permutations that's the best option.






          share|cite|improve this answer























          • Thanks, very helpful (although it feels like this shouldn't be this complicated but I guess that's on GAP).
            – Peter
            yesterday










          • There is also String - will update the answer now.
            – Alexander Konovalov
            yesterday














          2












          2








          2






          GAP has operations DisplayString, ViewSrting and PrintString documented here. Usually, displaying an object produces a human-readable relatively complete and verbose output, viewing produces a short and concise output, and printing produces an output in a complete form which is GAP readable (if at all possible), such that reading the output into GAP produces an object which is equal to the original one.



          Depending on the type of the object, they may delegate to each other in the order specified here.



          In the example in question, we have



          gap> PrintString(x);
          
"PartialPerm( >[ 1, 2 ], <>[ 3, 4 ]<> )<"
          
gap> ViewString(x);
          
">[>1<,>3<<]>[>2<,>4<<]"
          
gap> DisplayString(x);
          
"<object>n"


          As you see, the output have additional control characters < (ASCII 1) and > (ASCII 2) that allow proper line breaks. The function StripLineBreakCharacters (see here) may be used to remove them:



          gap> StripLineBreakCharacters(PrintString(x));
          
"PartialPerm( [ 1, 2 ], [ 3, 4 ] )"
          
gap> StripLineBreakCharacters(ViewString(x));
          
"[1,3][2,4]"
          
gap> StripLineBreakCharacters(DisplayString(x));
          
"<object>n"


          There is also String (see here) which should approximate as closely as possible the character sequence you see if you print an object:



          gap> String(x);
          
"PartialPerm( [ 1, 2 ], [ 3, 4 ] )"


          Perhaps for partial permutations that's the best option.






          share|cite|improve this answer














          GAP has operations DisplayString, ViewSrting and PrintString documented here. Usually, displaying an object produces a human-readable relatively complete and verbose output, viewing produces a short and concise output, and printing produces an output in a complete form which is GAP readable (if at all possible), such that reading the output into GAP produces an object which is equal to the original one.



          Depending on the type of the object, they may delegate to each other in the order specified here.



          In the example in question, we have



          gap> PrintString(x);
          
"PartialPerm( >[ 1, 2 ], <>[ 3, 4 ]<> )<"
          
gap> ViewString(x);
          
">[>1<,>3<<]>[>2<,>4<<]"
          
gap> DisplayString(x);
          
"<object>n"


          As you see, the output have additional control characters < (ASCII 1) and > (ASCII 2) that allow proper line breaks. The function StripLineBreakCharacters (see here) may be used to remove them:



          gap> StripLineBreakCharacters(PrintString(x));
          
"PartialPerm( [ 1, 2 ], [ 3, 4 ] )"
          
gap> StripLineBreakCharacters(ViewString(x));
          
"[1,3][2,4]"
          
gap> StripLineBreakCharacters(DisplayString(x));
          
"<object>n"


          There is also String (see here) which should approximate as closely as possible the character sequence you see if you print an object:



          gap> String(x);
          
"PartialPerm( [ 1, 2 ], [ 3, 4 ] )"


          Perhaps for partial permutations that's the best option.







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited yesterday

























          answered yesterday









          Alexander Konovalov

          5,16221956




          5,16221956












          • Thanks, very helpful (although it feels like this shouldn't be this complicated but I guess that's on GAP).
            – Peter
            yesterday










          • There is also String - will update the answer now.
            – Alexander Konovalov
            yesterday


















          • Thanks, very helpful (although it feels like this shouldn't be this complicated but I guess that's on GAP).
            – Peter
            yesterday










          • There is also String - will update the answer now.
            – Alexander Konovalov
            yesterday
















          Thanks, very helpful (although it feels like this shouldn't be this complicated but I guess that's on GAP).
          – Peter
          yesterday




          Thanks, very helpful (although it feels like this shouldn't be this complicated but I guess that's on GAP).
          – Peter
          yesterday












          There is also String - will update the answer now.
          – Alexander Konovalov
          yesterday




          There is also String - will update the answer now.
          – Alexander Konovalov
          yesterday


















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