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.

49.4k395200




49.4k395200










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

              47.8k466134




              47.8k466134








              • 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

                      Probability when a professor distributes a quiz and homework assignment to a class of n students.

                      Image
                      0 0 $begingroup$ Need help with this problem. Suppose our lazy professor collects a quiz and a homework assignment from a class of n students one day, then distributes both the quizzes and the homework assignments back to the class in a random fashion for grading. Each student receives one quiz and one homework assignment to grade. (a) What is the probability that every student receives someone else's quiz to grade, and someone else's homework to grade? (b) What is the probability that no student receives both their own quiz and their own homework assignment to grade? In this case, some students may receive their own quiz, and others may receive their own homework assignment. (c) Compute the limiting probability as n approaches infinity in each case. ...
                      Read more

                      Aardman Animations

                      Image
                      Aardman Animations, Ltd. Aardman Animations Tipo privada Atividade Animação em stop-motion , Animação em CGI Fundação 1972 Fundador(es) Peter Lord David Sproxton Sede Bristol, Inglaterra  Reino Unido Proprietário(s) Dreamworks Pessoas-chave Peter Lord David Sproxton Nick Park Divisões Aardman Features Aardman Digital Aardman Commercials Aardman Broadcast Aardman International Aardman Rights Aardman Effects Aardman 3-D Systems Aardman Nathan Love AardBoiled Website oficial aardman.com ...
                      Read more

                      Are they similar matrix

                      Image
                      0 $begingroup$ Do $begin{bmatrix} 0&i&0\0&0&1\0&0&0 end{bmatrix} $ and $begin{bmatrix} 0&0&0\-i&0&0\0&1&0 end{bmatrix} $ are similar.Is this True/false Clearly both are nilpotent and one is conjucate transpose of other but how to know if they are similar.i'm stuck. Please help me linear-algebra vector-spaces eigenvalues-eigenvectors generalizedeigenvector share | cite | improve this question edited Dec 10 '18 at 6:38 Vasanth Kris asked Dec 10 '18 at 6:19 ...
                      Read more