Min and Max of a list of Associations











up vote
10
down vote

favorite
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?






list-manipulation associations







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 at 6:30















up vote
10
down vote

favorite
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?






list-manipulation associations







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 at 6:30













up vote
10
down vote

favorite
1









up vote
10
down vote

favorite
1






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?






list-manipulation associations







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




list-manipulation associations






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Dec 7 at 6:22









C. E.

49.3k395199




49.3k395199










asked Dec 7 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 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 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 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 at 6:30










3 Answers
3






active

oldest

votes

















up vote
13
down vote



accepted










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






























    up vote
    6
    down vote













    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 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 at 13:45










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


















    up vote
    1
    down vote













    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',
      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








      up vote
      13
      down vote



      accepted










      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



























        up vote
        13
        down vote



        accepted










        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

























          up vote
          13
          down vote



          accepted







          up vote
          13
          down vote



          accepted






          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 at 8:30

























          answered Dec 7 at 6:22









          Shredderroy

          1,4931115




          1,4931115






















              up vote
              6
              down vote













              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 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 at 13:45










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















              up vote
              6
              down vote













              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 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 at 13:45










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













              up vote
              6
              down vote










              up vote
              6
              down vote









              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 at 6:34









              Henrik Schumacher

              47.4k466134




              47.4k466134








              • 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 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 at 13:45










              • Thanks, I am checking the link right now :)
                – Soner
                Dec 7 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 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 at 13:45










              • Thanks, I am checking the link right now :)
                – Soner
                Dec 7 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 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 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 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 at 13:45












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




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










              up vote
              1
              down vote













              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

























                up vote
                1
                down vote













                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























                  up vote
                  1
                  down vote










                  up vote
                  1
                  down vote









                  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 at 10:30









                  Edmund

                  25.5k330100




                  25.5k330100






























                      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

                      Image
                      Сан-Квентин Местоположение Сан-Квентин, Калифорния Координаты 37°56′13″ с. ш. 122°29′20″ з. д. H G Я O L Текущий статус Действует Режим безопасности минимальный и максимальный Количество мест 3 302 Открытие Июнь 1852 Находится в ведомстве California Department of Corrections and Rehabilitation Начальник Mike Martel, начальник  Сан-Квентин на Викискладе Сан-Квентин (англ.  San Quentin ) — тюрьма, располагающаяся на 432 акрах (около 1,7 км²), на мысе Сан-Квентин, в округе Марин, штат Калифорния, США. Тюрьма штата Калифорния Сан-Квентин была открыта в июле 1852 года и является старейшей в штате. Она была построена заключёнными, которые проживали в течение строительства на тюремном судне Вабан. В Сан-Квентине отбывали наказание и мужчины, и женщины до 1934 года, когда построили женскую тюрьму в Техачапи и туда перевели всех заключённых женщин. В Сан-Квентине приводятся в исполнение смертные казни, для этого имеется газовая камера, но...
                      Read more

                      8-я гвардейская общевойсковая армия

                      Image
                      8-я гвардейская общевойсковая ордена Ленина армия Награды: Войска: РККА → Советская армия → СВ России Род войск: Формирование: 1943 Расформирование (преобразование): 1992 Предшественник: 62-я армия (1942—43) → 8-я гвардейская общевойсковая армия (1943—92) → 8-й гвардейский армейский корпус (1992—98) Боевой путь Изюм-Барвенковская операция Донбасская операция Запорожская операция Битва за Днепр Днепропетровская операция Березнеговато-Снигирёвская операция Одесская операция Люблин-Брестская операция Варшавско-Познанская операция Восточно-Померанская операция Берлинская наступательная операция У этого термина существуют и другие значения, см. 8-я армия. Фотография Гвардейского Красного Знамени (лицевая сторона) 8-й гвардейской армии , образца 1943 года. Фотография Гвардейского Красного Знамени (оборотная сторона) 8-й гвардейской армии , образца 1943 года. 8-я гвардейская общевойсковая ордена Ленина армия  — гвардейское фор...
                      Read more

                      Алькесар

                      Image
                      Муниципалитет Алькесар Alquézar Герб 42°10′16″ с. ш. 0°01′27″ в. д. H G Я O L Страна Испания   Испания Автономное сообщество Арагон Провинция Уэска Комарка Сомонтано-де-Барбастро Алькальд Хосе Марияно Альтемир Ласкорс (ИСРП) История и география Площадь 32,36 км² Высота НУМ 660 м Часовой пояс UTC+1, летом UTC+2 Население Население 313 человек ( 2010 ) Плотность 9,92 чел./км² Этнохороним alquezarano/-a Цифровые идентификаторы Телефонный код +34 974 Почтовые индексы 22112 Автомобильный код HU alquezar.org   (исп.) Показать/скрыть карты Алькесар Алькесар Алькесар  Аудио, фото и видео на Викискладе Алькесар (исп.  Alquézar ) — муниципалитет в Испании, входит в провинцию Уэска, в составе автономного сообщества Арагон. Муниципалитет находится в составе района (комарки) Сомонтано-де-Барбастро. Занимает площадь 32,36 км². Население — 321 челове...
                      Read more