Min and Max of a list of Associations












10














I am trying to find the minimum values for all elements in a list of associations, below is an example



x = {<|"a"-> 4, "b"->9, "c"->15|>, <|"a"->21, "b"->11, "c"->1|>, <|"a"->12, "b"->3, "c"->21|>}



Required output for Min
{<|"a"-> 2, "b"->3, "c"->1|>}



Required output for Max
{<|"a"-> 21, "b"->11, "c"->15|>}




My attempt
for Max: MaximalBy[Values]@x
Result: {<|"a" -> 21, "b" -> 11, "c" -> 1|>}



for Min: MinimalBy[Values]@x
Result: {<|"a" -> 4, "b" -> 9, "c" -> 15|>}



Is there an elegant way to achieve this result?










share|improve this question




















  • 1




    I don't get it. How is the key a getting the value 2? That value does not appear for a in any of the associations. Similarly, why is the value of c not equal to 21 in the maximal result?
    – Shredderroy
    Dec 7 '18 at 6:30
















10














I am trying to find the minimum values for all elements in a list of associations, below is an example



x = {<|"a"-> 4, "b"->9, "c"->15|>, <|"a"->21, "b"->11, "c"->1|>, <|"a"->12, "b"->3, "c"->21|>}



Required output for Min
{<|"a"-> 2, "b"->3, "c"->1|>}



Required output for Max
{<|"a"-> 21, "b"->11, "c"->15|>}




My attempt
for Max: MaximalBy[Values]@x
Result: {<|"a" -> 21, "b" -> 11, "c" -> 1|>}



for Min: MinimalBy[Values]@x
Result: {<|"a" -> 4, "b" -> 9, "c" -> 15|>}



Is there an elegant way to achieve this result?










share|improve this question




















  • 1




    I don't get it. How is the key a getting the value 2? That value does not appear for a in any of the associations. Similarly, why is the value of c not equal to 21 in the maximal result?
    – Shredderroy
    Dec 7 '18 at 6:30














10












10








10


1





I am trying to find the minimum values for all elements in a list of associations, below is an example



x = {<|"a"-> 4, "b"->9, "c"->15|>, <|"a"->21, "b"->11, "c"->1|>, <|"a"->12, "b"->3, "c"->21|>}



Required output for Min
{<|"a"-> 2, "b"->3, "c"->1|>}



Required output for Max
{<|"a"-> 21, "b"->11, "c"->15|>}




My attempt
for Max: MaximalBy[Values]@x
Result: {<|"a" -> 21, "b" -> 11, "c" -> 1|>}



for Min: MinimalBy[Values]@x
Result: {<|"a" -> 4, "b" -> 9, "c" -> 15|>}



Is there an elegant way to achieve this result?










share|improve this question















I am trying to find the minimum values for all elements in a list of associations, below is an example



x = {<|"a"-> 4, "b"->9, "c"->15|>, <|"a"->21, "b"->11, "c"->1|>, <|"a"->12, "b"->3, "c"->21|>}



Required output for Min
{<|"a"-> 2, "b"->3, "c"->1|>}



Required output for Max
{<|"a"-> 21, "b"->11, "c"->15|>}




My attempt
for Max: MaximalBy[Values]@x
Result: {<|"a" -> 21, "b" -> 11, "c" -> 1|>}



for Min: MinimalBy[Values]@x
Result: {<|"a" -> 4, "b" -> 9, "c" -> 15|>}



Is there an elegant way to achieve this result?







list-manipulation associations






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Dec 7 '18 at 6:22









C. E.

49.8k397202




49.8k397202










asked Dec 7 '18 at 5:39









Professor Williams

533




533








  • 1




    I don't get it. How is the key a getting the value 2? That value does not appear for a in any of the associations. Similarly, why is the value of c not equal to 21 in the maximal result?
    – Shredderroy
    Dec 7 '18 at 6:30














  • 1




    I don't get it. How is the key a getting the value 2? That value does not appear for a in any of the associations. Similarly, why is the value of c not equal to 21 in the maximal result?
    – Shredderroy
    Dec 7 '18 at 6:30








1




1




I don't get it. How is the key a getting the value 2? That value does not appear for a in any of the associations. Similarly, why is the value of c not equal to 21 in the maximal result?
– Shredderroy
Dec 7 '18 at 6:30




I don't get it. How is the key a getting the value 2? That value does not appear for a in any of the associations. Similarly, why is the value of c not equal to 21 in the maximal result?
– Shredderroy
Dec 7 '18 at 6:30










3 Answers
3






active

oldest

votes


















13














How about



a = {
<|"a" -> 4, "b" -> 9, "c" -> 15|>,
<|"a" -> 21, "b" -> 11, "c" -> 1|>,
<|"a" -> 12, "b" -> 3, "c" -> 21|>
};

Merge[a, Min]

(*<|"a" -> 4, "b" -> 3, "c" -> 1|>*)

Merge[a, Max]

(*<|"a" -> 21, "b" -> 11, "c" -> 21|>*)


EDIT



Improved, as per Kuba's suggestion.






share|improve this answer































    6














    Random`Private`MapThreadMin[x]
    Random`Private`MapThreadMax[x]



    <|"a" -> 4, "b" -> 3, "c" -> 1|>



    <|"a" -> 21, "b" -> 11, "c" -> 21|>







    share|improve this answer

















    • 1




      is there any list out there for these "hidden" commands? Or do you happen to have a favourite list that you can share with us?
      – Soner
      Dec 7 '18 at 12:33






    • 1




      A good try is always ?**` ;) Honestly, I learned this trick very recently from Carl Woll. Some other good place to look for such things is What are some useful undocumented Mathematica functions?
      – Henrik Schumacher
      Dec 7 '18 at 13:45










    • Thanks, I am checking the link right now :)
      – Soner
      Dec 7 '18 at 21:35



















    1














    You may use Query and MinMax.



    With x as in OP.



    Query[Transpose /* Map[MinMax]]@x



    <|"a" -> {4, 21}, "b" -> {3, 11}, "c" -> {1, 21}|>



    You can produce a more descriptive result with AssociationThread.



    res = Query[Transpose /* Map[AssociationThread[{"Min", "Max"}, MinMax@#] &]]@x



    <|"a" -> <|"Min" -> 4, "Max" -> 21|>, 
    "b" -> <|"Min" -> 3, "Max" -> 11|>,
    "c" -> <|"Min" -> 1, "Max" -> 21|>|>



    Which you can then access by Key with Association's syntax sugar.



    res["a", "Max"]



    21



    Hope this helps.






    share|improve this answer





















      Your Answer





      StackExchange.ifUsing("editor", function () {
      return StackExchange.using("mathjaxEditing", function () {
      StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
      StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
      });
      });
      }, "mathjax-editing");

      StackExchange.ready(function() {
      var channelOptions = {
      tags: "".split(" "),
      id: "387"
      };
      initTagRenderer("".split(" "), "".split(" "), channelOptions);

      StackExchange.using("externalEditor", function() {
      // Have to fire editor after snippets, if snippets enabled
      if (StackExchange.settings.snippets.snippetsEnabled) {
      StackExchange.using("snippets", function() {
      createEditor();
      });
      }
      else {
      createEditor();
      }
      });

      function createEditor() {
      StackExchange.prepareEditor({
      heartbeatType: 'answer',
      autoActivateHeartbeat: false,
      convertImagesToLinks: false,
      noModals: true,
      showLowRepImageUploadWarning: true,
      reputationToPostImages: null,
      bindNavPrevention: true,
      postfix: "",
      imageUploader: {
      brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
      contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
      allowUrls: true
      },
      onDemand: true,
      discardSelector: ".discard-answer"
      ,immediatelyShowMarkdownHelp:true
      });


      }
      });














      draft saved

      draft discarded


















      StackExchange.ready(
      function () {
      StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmathematica.stackexchange.com%2fquestions%2f187472%2fmin-and-max-of-a-list-of-associations%23new-answer', 'question_page');
      }
      );

      Post as a guest















      Required, but never shown

























      3 Answers
      3






      active

      oldest

      votes








      3 Answers
      3






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      13














      How about



      a = {
      <|"a" -> 4, "b" -> 9, "c" -> 15|>,
      <|"a" -> 21, "b" -> 11, "c" -> 1|>,
      <|"a" -> 12, "b" -> 3, "c" -> 21|>
      };

      Merge[a, Min]

      (*<|"a" -> 4, "b" -> 3, "c" -> 1|>*)

      Merge[a, Max]

      (*<|"a" -> 21, "b" -> 11, "c" -> 21|>*)


      EDIT



      Improved, as per Kuba's suggestion.






      share|improve this answer




























        13














        How about



        a = {
        <|"a" -> 4, "b" -> 9, "c" -> 15|>,
        <|"a" -> 21, "b" -> 11, "c" -> 1|>,
        <|"a" -> 12, "b" -> 3, "c" -> 21|>
        };

        Merge[a, Min]

        (*<|"a" -> 4, "b" -> 3, "c" -> 1|>*)

        Merge[a, Max]

        (*<|"a" -> 21, "b" -> 11, "c" -> 21|>*)


        EDIT



        Improved, as per Kuba's suggestion.






        share|improve this answer


























          13












          13








          13






          How about



          a = {
          <|"a" -> 4, "b" -> 9, "c" -> 15|>,
          <|"a" -> 21, "b" -> 11, "c" -> 1|>,
          <|"a" -> 12, "b" -> 3, "c" -> 21|>
          };

          Merge[a, Min]

          (*<|"a" -> 4, "b" -> 3, "c" -> 1|>*)

          Merge[a, Max]

          (*<|"a" -> 21, "b" -> 11, "c" -> 21|>*)


          EDIT



          Improved, as per Kuba's suggestion.






          share|improve this answer














          How about



          a = {
          <|"a" -> 4, "b" -> 9, "c" -> 15|>,
          <|"a" -> 21, "b" -> 11, "c" -> 1|>,
          <|"a" -> 12, "b" -> 3, "c" -> 21|>
          };

          Merge[a, Min]

          (*<|"a" -> 4, "b" -> 3, "c" -> 1|>*)

          Merge[a, Max]

          (*<|"a" -> 21, "b" -> 11, "c" -> 21|>*)


          EDIT



          Improved, as per Kuba's suggestion.







          share|improve this answer














          share|improve this answer



          share|improve this answer








          edited Dec 7 '18 at 8:30

























          answered Dec 7 '18 at 6:22









          Shredderroy

          1,4931115




          1,4931115























              6














              Random`Private`MapThreadMin[x]
              Random`Private`MapThreadMax[x]



              <|"a" -> 4, "b" -> 3, "c" -> 1|>



              <|"a" -> 21, "b" -> 11, "c" -> 21|>







              share|improve this answer

















              • 1




                is there any list out there for these "hidden" commands? Or do you happen to have a favourite list that you can share with us?
                – Soner
                Dec 7 '18 at 12:33






              • 1




                A good try is always ?**` ;) Honestly, I learned this trick very recently from Carl Woll. Some other good place to look for such things is What are some useful undocumented Mathematica functions?
                – Henrik Schumacher
                Dec 7 '18 at 13:45










              • Thanks, I am checking the link right now :)
                – Soner
                Dec 7 '18 at 21:35
















              6














              Random`Private`MapThreadMin[x]
              Random`Private`MapThreadMax[x]



              <|"a" -> 4, "b" -> 3, "c" -> 1|>



              <|"a" -> 21, "b" -> 11, "c" -> 21|>







              share|improve this answer

















              • 1




                is there any list out there for these "hidden" commands? Or do you happen to have a favourite list that you can share with us?
                – Soner
                Dec 7 '18 at 12:33






              • 1




                A good try is always ?**` ;) Honestly, I learned this trick very recently from Carl Woll. Some other good place to look for such things is What are some useful undocumented Mathematica functions?
                – Henrik Schumacher
                Dec 7 '18 at 13:45










              • Thanks, I am checking the link right now :)
                – Soner
                Dec 7 '18 at 21:35














              6












              6








              6






              Random`Private`MapThreadMin[x]
              Random`Private`MapThreadMax[x]



              <|"a" -> 4, "b" -> 3, "c" -> 1|>



              <|"a" -> 21, "b" -> 11, "c" -> 21|>







              share|improve this answer












              Random`Private`MapThreadMin[x]
              Random`Private`MapThreadMax[x]



              <|"a" -> 4, "b" -> 3, "c" -> 1|>



              <|"a" -> 21, "b" -> 11, "c" -> 21|>








              share|improve this answer












              share|improve this answer



              share|improve this answer










              answered Dec 7 '18 at 6:34









              Henrik Schumacher

              48.8k467139




              48.8k467139








              • 1




                is there any list out there for these "hidden" commands? Or do you happen to have a favourite list that you can share with us?
                – Soner
                Dec 7 '18 at 12:33






              • 1




                A good try is always ?**` ;) Honestly, I learned this trick very recently from Carl Woll. Some other good place to look for such things is What are some useful undocumented Mathematica functions?
                – Henrik Schumacher
                Dec 7 '18 at 13:45










              • Thanks, I am checking the link right now :)
                – Soner
                Dec 7 '18 at 21:35














              • 1




                is there any list out there for these "hidden" commands? Or do you happen to have a favourite list that you can share with us?
                – Soner
                Dec 7 '18 at 12:33






              • 1




                A good try is always ?**` ;) Honestly, I learned this trick very recently from Carl Woll. Some other good place to look for such things is What are some useful undocumented Mathematica functions?
                – Henrik Schumacher
                Dec 7 '18 at 13:45










              • Thanks, I am checking the link right now :)
                – Soner
                Dec 7 '18 at 21:35








              1




              1




              is there any list out there for these "hidden" commands? Or do you happen to have a favourite list that you can share with us?
              – Soner
              Dec 7 '18 at 12:33




              is there any list out there for these "hidden" commands? Or do you happen to have a favourite list that you can share with us?
              – Soner
              Dec 7 '18 at 12:33




              1




              1




              A good try is always ?**` ;) Honestly, I learned this trick very recently from Carl Woll. Some other good place to look for such things is What are some useful undocumented Mathematica functions?
              – Henrik Schumacher
              Dec 7 '18 at 13:45




              A good try is always ?**` ;) Honestly, I learned this trick very recently from Carl Woll. Some other good place to look for such things is What are some useful undocumented Mathematica functions?
              – Henrik Schumacher
              Dec 7 '18 at 13:45












              Thanks, I am checking the link right now :)
              – Soner
              Dec 7 '18 at 21:35




              Thanks, I am checking the link right now :)
              – Soner
              Dec 7 '18 at 21:35











              1














              You may use Query and MinMax.



              With x as in OP.



              Query[Transpose /* Map[MinMax]]@x



              <|"a" -> {4, 21}, "b" -> {3, 11}, "c" -> {1, 21}|>



              You can produce a more descriptive result with AssociationThread.



              res = Query[Transpose /* Map[AssociationThread[{"Min", "Max"}, MinMax@#] &]]@x



              <|"a" -> <|"Min" -> 4, "Max" -> 21|>, 
              "b" -> <|"Min" -> 3, "Max" -> 11|>,
              "c" -> <|"Min" -> 1, "Max" -> 21|>|>



              Which you can then access by Key with Association's syntax sugar.



              res["a", "Max"]



              21



              Hope this helps.






              share|improve this answer


























                1














                You may use Query and MinMax.



                With x as in OP.



                Query[Transpose /* Map[MinMax]]@x



                <|"a" -> {4, 21}, "b" -> {3, 11}, "c" -> {1, 21}|>



                You can produce a more descriptive result with AssociationThread.



                res = Query[Transpose /* Map[AssociationThread[{"Min", "Max"}, MinMax@#] &]]@x



                <|"a" -> <|"Min" -> 4, "Max" -> 21|>, 
                "b" -> <|"Min" -> 3, "Max" -> 11|>,
                "c" -> <|"Min" -> 1, "Max" -> 21|>|>



                Which you can then access by Key with Association's syntax sugar.



                res["a", "Max"]



                21



                Hope this helps.






                share|improve this answer
























                  1












                  1








                  1






                  You may use Query and MinMax.



                  With x as in OP.



                  Query[Transpose /* Map[MinMax]]@x



                  <|"a" -> {4, 21}, "b" -> {3, 11}, "c" -> {1, 21}|>



                  You can produce a more descriptive result with AssociationThread.



                  res = Query[Transpose /* Map[AssociationThread[{"Min", "Max"}, MinMax@#] &]]@x



                  <|"a" -> <|"Min" -> 4, "Max" -> 21|>, 
                  "b" -> <|"Min" -> 3, "Max" -> 11|>,
                  "c" -> <|"Min" -> 1, "Max" -> 21|>|>



                  Which you can then access by Key with Association's syntax sugar.



                  res["a", "Max"]



                  21



                  Hope this helps.






                  share|improve this answer












                  You may use Query and MinMax.



                  With x as in OP.



                  Query[Transpose /* Map[MinMax]]@x



                  <|"a" -> {4, 21}, "b" -> {3, 11}, "c" -> {1, 21}|>



                  You can produce a more descriptive result with AssociationThread.



                  res = Query[Transpose /* Map[AssociationThread[{"Min", "Max"}, MinMax@#] &]]@x



                  <|"a" -> <|"Min" -> 4, "Max" -> 21|>, 
                  "b" -> <|"Min" -> 3, "Max" -> 11|>,
                  "c" -> <|"Min" -> 1, "Max" -> 21|>|>



                  Which you can then access by Key with Association's syntax sugar.



                  res["a", "Max"]



                  21



                  Hope this helps.







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered Dec 7 '18 at 10:30









                  Edmund

                  25.7k330100




                  25.7k330100






























                      draft saved

                      draft discarded




















































                      Thanks for contributing an answer to Mathematica Stack Exchange!


                      • Please be sure to answer the question. Provide details and share your research!

                      But avoid



                      • Asking for help, clarification, or responding to other answers.

                      • Making statements based on opinion; back them up with references or personal experience.


                      Use MathJax to format equations. MathJax reference.


                      To learn more, see our tips on writing great answers.





                      Some of your past answers have not been well-received, and you're in danger of being blocked from answering.


                      Please pay close attention to the following guidance:


                      • Please be sure to answer the question. Provide details and share your research!

                      But avoid



                      • Asking for help, clarification, or responding to other answers.

                      • Making statements based on opinion; back them up with references or personal experience.


                      To learn more, see our tips on writing great answers.




                      draft saved


                      draft discarded














                      StackExchange.ready(
                      function () {
                      StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmathematica.stackexchange.com%2fquestions%2f187472%2fmin-and-max-of-a-list-of-associations%23new-answer', 'question_page');
                      }
                      );

                      Post as a guest















                      Required, but never shown





















































                      Required, but never shown














                      Required, but never shown












                      Required, but never shown







                      Required, but never shown

































                      Required, but never shown














                      Required, but never shown












                      Required, but never shown







                      Required, but never shown







                      Popular posts from this blog

                      Сан-Квентин

                      8-я гвардейская общевойсковая армия

                      Алькесар