Substitution rule for sums of similar objects?

The name of the pictureThe name of the pictureThe name of the pictureClash Royale CLAN TAG#URR8PPP











up vote
3
down vote

favorite












Consider objects like



obj= (Sum[Subscript[A, i], i, 1, 5] Sum[Subscript[A, i], i, 3, 6] Sum[Subscript[A, i], i, 2, 3])/(
 Sum[Subscript[A, i], i, 3, 8] Sum[Subscript[A, i], i, 1, 2] Sum[Subscript[A, i], i, 4, 6])



enter image description here




I would like to have a substitution rule myRule that would perform the following replacement



obj /. myRule



enter image description here




for sequences of sums of $A_i$ of any lengths, and with indices not necessarily consecutive and not necessarily integer. How can this be done?






function-construction pattern-matching replacement







share|improve this question



























    up vote
    3
    down vote

    favorite












    Consider objects like



    obj= (Sum[Subscript[A, i], i, 1, 5] Sum[Subscript[A, i], i, 3, 6] Sum[Subscript[A, i], i, 2, 3])/(
     Sum[Subscript[A, i], i, 3, 8] Sum[Subscript[A, i], i, 1, 2] Sum[Subscript[A, i], i, 4, 6])



    enter image description here




    I would like to have a substitution rule myRule that would perform the following replacement



    obj /. myRule



    enter image description here




    for sequences of sums of $A_i$ of any lengths, and with indices not necessarily consecutive and not necessarily integer. How can this be done?






    function-construction pattern-matching replacement







    share|improve this question

























      up vote
      3
      down vote

      favorite









      up vote
      3
      down vote

      favorite











      Consider objects like



      obj= (Sum[Subscript[A, i], i, 1, 5] Sum[Subscript[A, i], i, 3, 6] Sum[Subscript[A, i], i, 2, 3])/(
       Sum[Subscript[A, i], i, 3, 8] Sum[Subscript[A, i], i, 1, 2] Sum[Subscript[A, i], i, 4, 6])



      enter image description here




      I would like to have a substitution rule myRule that would perform the following replacement



      obj /. myRule



      enter image description here




      for sequences of sums of $A_i$ of any lengths, and with indices not necessarily consecutive and not necessarily integer. How can this be done?






      function-construction pattern-matching replacement







      share|improve this question















      Consider objects like



      obj= (Sum[Subscript[A, i], i, 1, 5] Sum[Subscript[A, i], i, 3, 6] Sum[Subscript[A, i], i, 2, 3])/(
       Sum[Subscript[A, i], i, 3, 8] Sum[Subscript[A, i], i, 1, 2] Sum[Subscript[A, i], i, 4, 6])



      enter image description here




      I would like to have a substitution rule myRule that would perform the following replacement



      obj /. myRule



      enter image description here




      for sequences of sums of $A_i$ of any lengths, and with indices not necessarily consecutive and not necessarily integer. How can this be done?






      function-construction pattern-matching replacement




      function-construction pattern-matching replacement






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited 2 hours ago









      xzczd

      24.9k466235




      24.9k466235










      asked 3 hours ago









      Kagaratsch

      4,42431246




      4,42431246




















          3 Answers
          3






          active

          oldest

          votes

















          up vote
          3
          down vote



          accepted










          Try the following:



          obj /. HoldPattern@Plus@a : (h : Subscript)[A, _] .. :> h[A, ## & @@ Last /@ a]


          It can be even shorter:



          obj /. HoldPattern@+a : (h : Subscript)[A, _] .. :> h[A, ## & @@ Last /@ a]





          share|improve this answer





























            up vote
            1
            down vote













            Here's an alternative that will work with subscripted As that have more than one subscript, which may (or may not) be what you want:



            obj /. HoldPattern[Plus[seq : Subscript[A, __] ..]] :>
             Subscript[A, Sequence @@ Cases[seq, Subscript[A, inds__] :> inds]]





            share|improve this answer



























              up vote
              0
              down vote













              Block[Plus = (Subscript[#[[1]], ## & @@ ##[[All, -1]]] &), obj] // TeXForm



              $largefracA_2,3 A_3,4,5,6 A_1,2,3,4,5A_1,2 A_4,5,6 A_3,4,5,6,7,8$




              Alternatively,



              obj /. Plus -> (Subscript[#[[1]], ## & @@ ##[[All, -1]]] &) // TeXForm



              $largefracA_2,3 A_3,4,5,6 A_1,2,3,4,5A_1,2 A_4,5,6 A_3,4,5,6,7,8$







              share|improve this answer




















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                3 Answers
                3






                active

                oldest

                votes








                3 Answers
                3






                active

                oldest

                votes









                active

                oldest

                votes






                active

                oldest

                votes








                up vote
                3
                down vote



                accepted










                Try the following:



                obj /. HoldPattern@Plus@a : (h : Subscript)[A, _] .. :> h[A, ## & @@ Last /@ a]


                It can be even shorter:



                obj /. HoldPattern@+a : (h : Subscript)[A, _] .. :> h[A, ## & @@ Last /@ a]





                share|improve this answer


























                  up vote
                  3
                  down vote



                  accepted










                  Try the following:



                  obj /. HoldPattern@Plus@a : (h : Subscript)[A, _] .. :> h[A, ## & @@ Last /@ a]


                  It can be even shorter:



                  obj /. HoldPattern@+a : (h : Subscript)[A, _] .. :> h[A, ## & @@ Last /@ a]





                  share|improve this answer
























                    up vote
                    3
                    down vote



                    accepted







                    up vote
                    3
                    down vote



                    accepted






                    Try the following:



                    obj /. HoldPattern@Plus@a : (h : Subscript)[A, _] .. :> h[A, ## & @@ Last /@ a]


                    It can be even shorter:



                    obj /. HoldPattern@+a : (h : Subscript)[A, _] .. :> h[A, ## & @@ Last /@ a]





                    share|improve this answer














                    Try the following:



                    obj /. HoldPattern@Plus@a : (h : Subscript)[A, _] .. :> h[A, ## & @@ Last /@ a]


                    It can be even shorter:



                    obj /. HoldPattern@+a : (h : Subscript)[A, _] .. :> h[A, ## & @@ Last /@ a]






                    share|improve this answer














                    share|improve this answer



                    share|improve this answer








                    edited 2 hours ago

























                    answered 3 hours ago









                    xzczd

                    24.9k466235




                    24.9k466235




















                        up vote
                        1
                        down vote













                        Here's an alternative that will work with subscripted As that have more than one subscript, which may (or may not) be what you want:



                        obj /. HoldPattern[Plus[seq : Subscript[A, __] ..]] :>
                         Subscript[A, Sequence @@ Cases[seq, Subscript[A, inds__] :> inds]]





                        share|improve this answer
























                          up vote
                          1
                          down vote













                          Here's an alternative that will work with subscripted As that have more than one subscript, which may (or may not) be what you want:



                          obj /. HoldPattern[Plus[seq : Subscript[A, __] ..]] :>
                           Subscript[A, Sequence @@ Cases[seq, Subscript[A, inds__] :> inds]]





                          share|improve this answer






















                            up vote
                            1
                            down vote










                            up vote
                            1
                            down vote









                            Here's an alternative that will work with subscripted As that have more than one subscript, which may (or may not) be what you want:



                            obj /. HoldPattern[Plus[seq : Subscript[A, __] ..]] :>
                             Subscript[A, Sequence @@ Cases[seq, Subscript[A, inds__] :> inds]]





                            share|improve this answer












                            Here's an alternative that will work with subscripted As that have more than one subscript, which may (or may not) be what you want:



                            obj /. HoldPattern[Plus[seq : Subscript[A, __] ..]] :>
                             Subscript[A, Sequence @@ Cases[seq, Subscript[A, inds__] :> inds]]






                            share|improve this answer












                            share|improve this answer



                            share|improve this answer










                            answered 57 mins ago









                            Pillsy

                            12.5k13179




                            12.5k13179




















                                up vote
                                0
                                down vote













                                Block[Plus = (Subscript[#[[1]], ## & @@ ##[[All, -1]]] &), obj] // TeXForm



                                $largefracA_2,3 A_3,4,5,6 A_1,2,3,4,5A_1,2 A_4,5,6 A_3,4,5,6,7,8$




                                Alternatively,



                                obj /. Plus -> (Subscript[#[[1]], ## & @@ ##[[All, -1]]] &) // TeXForm



                                $largefracA_2,3 A_3,4,5,6 A_1,2,3,4,5A_1,2 A_4,5,6 A_3,4,5,6,7,8$







                                share|improve this answer
























                                  up vote
                                  0
                                  down vote













                                  Block[Plus = (Subscript[#[[1]], ## & @@ ##[[All, -1]]] &), obj] // TeXForm



                                  $largefracA_2,3 A_3,4,5,6 A_1,2,3,4,5A_1,2 A_4,5,6 A_3,4,5,6,7,8$




                                  Alternatively,



                                  obj /. Plus -> (Subscript[#[[1]], ## & @@ ##[[All, -1]]] &) // TeXForm



                                  $largefracA_2,3 A_3,4,5,6 A_1,2,3,4,5A_1,2 A_4,5,6 A_3,4,5,6,7,8$







                                  share|improve this answer






















                                    up vote
                                    0
                                    down vote










                                    up vote
                                    0
                                    down vote









                                    Block[Plus = (Subscript[#[[1]], ## & @@ ##[[All, -1]]] &), obj] // TeXForm



                                    $largefracA_2,3 A_3,4,5,6 A_1,2,3,4,5A_1,2 A_4,5,6 A_3,4,5,6,7,8$




                                    Alternatively,



                                    obj /. Plus -> (Subscript[#[[1]], ## & @@ ##[[All, -1]]] &) // TeXForm



                                    $largefracA_2,3 A_3,4,5,6 A_1,2,3,4,5A_1,2 A_4,5,6 A_3,4,5,6,7,8$







                                    share|improve this answer












                                    Block[Plus = (Subscript[#[[1]], ## & @@ ##[[All, -1]]] &), obj] // TeXForm



                                    $largefracA_2,3 A_3,4,5,6 A_1,2,3,4,5A_1,2 A_4,5,6 A_3,4,5,6,7,8$




                                    Alternatively,



                                    obj /. Plus -> (Subscript[#[[1]], ## & @@ ##[[All, -1]]] &) // TeXForm



                                    $largefracA_2,3 A_3,4,5,6 A_1,2,3,4,5A_1,2 A_4,5,6 A_3,4,5,6,7,8$








                                    share|improve this answer












                                    share|improve this answer



                                    share|improve this answer










                                    answered 13 mins ago









                                    kglr

                                    167k8188390




                                    167k8188390



























                                         

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