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?






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 '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?






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 '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?






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 '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





















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      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






























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