Truncate a set of lists until a subset of entries matches?












3














Consider lists of vectors of elements like



list[1]={{a1,b1,c11},{a2,b2,c12},{a3,b3,c13},{a4,b4,c14},{a5,b5,c15}};
list[2]={{a1,b1,c21} ,{a3,b3,c23},{a4,b4,c24},{a5,b5,c25}};
list[3]={{a1,b1,c31},{a2,b2,c32},{a3,b3,c33} ,{a5,b5,c35}};


where the length 3 of vectors in lists is just an example and could be longer, and there may be more than 3 such lists.



I would like to have a function truncate[listoflists_] that takes all these lists and truncates them to only have the vectors containing ai,bi entries that are present in all of them:



{list[1],list[2],list[3]}=truncate[{list[1],list[2],list[3]}];
list[1]
list[2]
list[3]



{{a1,b1,c11},{a3,b3,c13},{a5,b5,c15}}



{{a1,b1,c21},{a3,b3,c23},{a5,b5,c25}}



{{a1,b1,c31},{a3,b3,c33},{a5,b5,c35}}




Is there a quick way to do this in Mathematica? Thanks for any suggestion.










share|improve this question



























    3














    Consider lists of vectors of elements like



    list[1]={{a1,b1,c11},{a2,b2,c12},{a3,b3,c13},{a4,b4,c14},{a5,b5,c15}};
    list[2]={{a1,b1,c21} ,{a3,b3,c23},{a4,b4,c24},{a5,b5,c25}};
    list[3]={{a1,b1,c31},{a2,b2,c32},{a3,b3,c33} ,{a5,b5,c35}};


    where the length 3 of vectors in lists is just an example and could be longer, and there may be more than 3 such lists.



    I would like to have a function truncate[listoflists_] that takes all these lists and truncates them to only have the vectors containing ai,bi entries that are present in all of them:



    {list[1],list[2],list[3]}=truncate[{list[1],list[2],list[3]}];
    list[1]
    list[2]
    list[3]



    {{a1,b1,c11},{a3,b3,c13},{a5,b5,c15}}



    {{a1,b1,c21},{a3,b3,c23},{a5,b5,c25}}



    {{a1,b1,c31},{a3,b3,c33},{a5,b5,c35}}




    Is there a quick way to do this in Mathematica? Thanks for any suggestion.










    share|improve this question

























      3












      3








      3







      Consider lists of vectors of elements like



      list[1]={{a1,b1,c11},{a2,b2,c12},{a3,b3,c13},{a4,b4,c14},{a5,b5,c15}};
      list[2]={{a1,b1,c21} ,{a3,b3,c23},{a4,b4,c24},{a5,b5,c25}};
      list[3]={{a1,b1,c31},{a2,b2,c32},{a3,b3,c33} ,{a5,b5,c35}};


      where the length 3 of vectors in lists is just an example and could be longer, and there may be more than 3 such lists.



      I would like to have a function truncate[listoflists_] that takes all these lists and truncates them to only have the vectors containing ai,bi entries that are present in all of them:



      {list[1],list[2],list[3]}=truncate[{list[1],list[2],list[3]}];
      list[1]
      list[2]
      list[3]



      {{a1,b1,c11},{a3,b3,c13},{a5,b5,c15}}



      {{a1,b1,c21},{a3,b3,c23},{a5,b5,c25}}



      {{a1,b1,c31},{a3,b3,c33},{a5,b5,c35}}




      Is there a quick way to do this in Mathematica? Thanks for any suggestion.










      share|improve this question













      Consider lists of vectors of elements like



      list[1]={{a1,b1,c11},{a2,b2,c12},{a3,b3,c13},{a4,b4,c14},{a5,b5,c15}};
      list[2]={{a1,b1,c21} ,{a3,b3,c23},{a4,b4,c24},{a5,b5,c25}};
      list[3]={{a1,b1,c31},{a2,b2,c32},{a3,b3,c33} ,{a5,b5,c35}};


      where the length 3 of vectors in lists is just an example and could be longer, and there may be more than 3 such lists.



      I would like to have a function truncate[listoflists_] that takes all these lists and truncates them to only have the vectors containing ai,bi entries that are present in all of them:



      {list[1],list[2],list[3]}=truncate[{list[1],list[2],list[3]}];
      list[1]
      list[2]
      list[3]



      {{a1,b1,c11},{a3,b3,c13},{a5,b5,c15}}



      {{a1,b1,c21},{a3,b3,c23},{a5,b5,c25}}



      {{a1,b1,c31},{a3,b3,c33},{a5,b5,c35}}




      Is there a quick way to do this in Mathematica? Thanks for any suggestion.







      list-manipulation function-construction






      share|improve this question













      share|improve this question











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      asked Nov 23 '18 at 21:04









      KagaratschKagaratsch

      4,59231246




      4,59231246






















          2 Answers
          2






          active

          oldest

          votes


















          3














          It is short (does not mean quick) to get it via associations:



          truncate = Values @ KeyIntersection @ Map[#[[;; 2]] -> # &, #, {2}] &


          We convert {a1,b1,c11} to {a1,b1}->{a1,b1,c11} and everything else is straightforward.






          share|improve this answer



















          • 1




            Love it when a mod ends up in the LQ review. :)
            – Michael E2
            Nov 23 '18 at 21:45










          • @MichaelE2 ok, explanation added.
            – Kuba
            Nov 23 '18 at 21:53










          • I approved it anyway. It's not always clear that excessive exposition would be an improvement.
            – Michael E2
            Nov 23 '18 at 22:00










          • I have changed it to truncate = Values@KeyIntersection@Map[{#[[1]], #[[2]]} -> # &, #, {2}] & to make it compatible with longer vector cases.
            – Kagaratsch
            Nov 23 '18 at 23:35






          • 1




            @Kagaratsch right, you mentioned it. I edited the code.
            – Kuba
            Nov 24 '18 at 0:27



















          1














          Also



          tF = Module[{i = Intersection@@#[[;;, ;;, #2]], k = #2}, Select[MemberQ[i, #[[k]]]&]/@ #]&

          lists = list /@ {1, 2, 3};
          tF[lists, {1, 2}]



          {{{a1, b1, c11}, {a3, b3, c13}, {a5, b5, c15}},

          {{a1, b1, c21}, {a3, b3, c23}, {a5, b5, c25}},

          {{a1, b1, c31}, {a3, b3, c33}, {a5, b5, c35}}}







          share|improve this answer





















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            2 Answers
            2






            active

            oldest

            votes








            2 Answers
            2






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            3














            It is short (does not mean quick) to get it via associations:



            truncate = Values @ KeyIntersection @ Map[#[[;; 2]] -> # &, #, {2}] &


            We convert {a1,b1,c11} to {a1,b1}->{a1,b1,c11} and everything else is straightforward.






            share|improve this answer



















            • 1




              Love it when a mod ends up in the LQ review. :)
              – Michael E2
              Nov 23 '18 at 21:45










            • @MichaelE2 ok, explanation added.
              – Kuba
              Nov 23 '18 at 21:53










            • I approved it anyway. It's not always clear that excessive exposition would be an improvement.
              – Michael E2
              Nov 23 '18 at 22:00










            • I have changed it to truncate = Values@KeyIntersection@Map[{#[[1]], #[[2]]} -> # &, #, {2}] & to make it compatible with longer vector cases.
              – Kagaratsch
              Nov 23 '18 at 23:35






            • 1




              @Kagaratsch right, you mentioned it. I edited the code.
              – Kuba
              Nov 24 '18 at 0:27
















            3














            It is short (does not mean quick) to get it via associations:



            truncate = Values @ KeyIntersection @ Map[#[[;; 2]] -> # &, #, {2}] &


            We convert {a1,b1,c11} to {a1,b1}->{a1,b1,c11} and everything else is straightforward.






            share|improve this answer



















            • 1




              Love it when a mod ends up in the LQ review. :)
              – Michael E2
              Nov 23 '18 at 21:45










            • @MichaelE2 ok, explanation added.
              – Kuba
              Nov 23 '18 at 21:53










            • I approved it anyway. It's not always clear that excessive exposition would be an improvement.
              – Michael E2
              Nov 23 '18 at 22:00










            • I have changed it to truncate = Values@KeyIntersection@Map[{#[[1]], #[[2]]} -> # &, #, {2}] & to make it compatible with longer vector cases.
              – Kagaratsch
              Nov 23 '18 at 23:35






            • 1




              @Kagaratsch right, you mentioned it. I edited the code.
              – Kuba
              Nov 24 '18 at 0:27














            3












            3








            3






            It is short (does not mean quick) to get it via associations:



            truncate = Values @ KeyIntersection @ Map[#[[;; 2]] -> # &, #, {2}] &


            We convert {a1,b1,c11} to {a1,b1}->{a1,b1,c11} and everything else is straightforward.






            share|improve this answer














            It is short (does not mean quick) to get it via associations:



            truncate = Values @ KeyIntersection @ Map[#[[;; 2]] -> # &, #, {2}] &


            We convert {a1,b1,c11} to {a1,b1}->{a1,b1,c11} and everything else is straightforward.







            share|improve this answer














            share|improve this answer



            share|improve this answer








            edited Nov 24 '18 at 0:27

























            answered Nov 23 '18 at 21:23









            KubaKuba

            104k12201518




            104k12201518








            • 1




              Love it when a mod ends up in the LQ review. :)
              – Michael E2
              Nov 23 '18 at 21:45










            • @MichaelE2 ok, explanation added.
              – Kuba
              Nov 23 '18 at 21:53










            • I approved it anyway. It's not always clear that excessive exposition would be an improvement.
              – Michael E2
              Nov 23 '18 at 22:00










            • I have changed it to truncate = Values@KeyIntersection@Map[{#[[1]], #[[2]]} -> # &, #, {2}] & to make it compatible with longer vector cases.
              – Kagaratsch
              Nov 23 '18 at 23:35






            • 1




              @Kagaratsch right, you mentioned it. I edited the code.
              – Kuba
              Nov 24 '18 at 0:27














            • 1




              Love it when a mod ends up in the LQ review. :)
              – Michael E2
              Nov 23 '18 at 21:45










            • @MichaelE2 ok, explanation added.
              – Kuba
              Nov 23 '18 at 21:53










            • I approved it anyway. It's not always clear that excessive exposition would be an improvement.
              – Michael E2
              Nov 23 '18 at 22:00










            • I have changed it to truncate = Values@KeyIntersection@Map[{#[[1]], #[[2]]} -> # &, #, {2}] & to make it compatible with longer vector cases.
              – Kagaratsch
              Nov 23 '18 at 23:35






            • 1




              @Kagaratsch right, you mentioned it. I edited the code.
              – Kuba
              Nov 24 '18 at 0:27








            1




            1




            Love it when a mod ends up in the LQ review. :)
            – Michael E2
            Nov 23 '18 at 21:45




            Love it when a mod ends up in the LQ review. :)
            – Michael E2
            Nov 23 '18 at 21:45












            @MichaelE2 ok, explanation added.
            – Kuba
            Nov 23 '18 at 21:53




            @MichaelE2 ok, explanation added.
            – Kuba
            Nov 23 '18 at 21:53












            I approved it anyway. It's not always clear that excessive exposition would be an improvement.
            – Michael E2
            Nov 23 '18 at 22:00




            I approved it anyway. It's not always clear that excessive exposition would be an improvement.
            – Michael E2
            Nov 23 '18 at 22:00












            I have changed it to truncate = Values@KeyIntersection@Map[{#[[1]], #[[2]]} -> # &, #, {2}] & to make it compatible with longer vector cases.
            – Kagaratsch
            Nov 23 '18 at 23:35




            I have changed it to truncate = Values@KeyIntersection@Map[{#[[1]], #[[2]]} -> # &, #, {2}] & to make it compatible with longer vector cases.
            – Kagaratsch
            Nov 23 '18 at 23:35




            1




            1




            @Kagaratsch right, you mentioned it. I edited the code.
            – Kuba
            Nov 24 '18 at 0:27




            @Kagaratsch right, you mentioned it. I edited the code.
            – Kuba
            Nov 24 '18 at 0:27











            1














            Also



            tF = Module[{i = Intersection@@#[[;;, ;;, #2]], k = #2}, Select[MemberQ[i, #[[k]]]&]/@ #]&

            lists = list /@ {1, 2, 3};
            tF[lists, {1, 2}]



            {{{a1, b1, c11}, {a3, b3, c13}, {a5, b5, c15}},

            {{a1, b1, c21}, {a3, b3, c23}, {a5, b5, c25}},

            {{a1, b1, c31}, {a3, b3, c33}, {a5, b5, c35}}}







            share|improve this answer


























              1














              Also



              tF = Module[{i = Intersection@@#[[;;, ;;, #2]], k = #2}, Select[MemberQ[i, #[[k]]]&]/@ #]&

              lists = list /@ {1, 2, 3};
              tF[lists, {1, 2}]



              {{{a1, b1, c11}, {a3, b3, c13}, {a5, b5, c15}},

              {{a1, b1, c21}, {a3, b3, c23}, {a5, b5, c25}},

              {{a1, b1, c31}, {a3, b3, c33}, {a5, b5, c35}}}







              share|improve this answer
























                1












                1








                1






                Also



                tF = Module[{i = Intersection@@#[[;;, ;;, #2]], k = #2}, Select[MemberQ[i, #[[k]]]&]/@ #]&

                lists = list /@ {1, 2, 3};
                tF[lists, {1, 2}]



                {{{a1, b1, c11}, {a3, b3, c13}, {a5, b5, c15}},

                {{a1, b1, c21}, {a3, b3, c23}, {a5, b5, c25}},

                {{a1, b1, c31}, {a3, b3, c33}, {a5, b5, c35}}}







                share|improve this answer












                Also



                tF = Module[{i = Intersection@@#[[;;, ;;, #2]], k = #2}, Select[MemberQ[i, #[[k]]]&]/@ #]&

                lists = list /@ {1, 2, 3};
                tF[lists, {1, 2}]



                {{{a1, b1, c11}, {a3, b3, c13}, {a5, b5, c15}},

                {{a1, b1, c21}, {a3, b3, c23}, {a5, b5, c25}},

                {{a1, b1, c31}, {a3, b3, c33}, {a5, b5, c35}}}








                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Nov 24 '18 at 19:32









                kglrkglr

                178k9198409




                178k9198409






























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