Iterate over keys of association












3












$begingroup$


How do you iterate over the keys or rules of an association (in any order)? E.g. for 



<|"0"->"a", "1"->"b", "2"->"c"|>


I would like to either iterate over "0", "1", "2" or tuples containing each key and value.



For example, something that performed the equivalent of a python dictionary's items, method would be ideal (which returns a list (or iterator) in the form [(key1, value1), ...], so {{"0", "a"}, {"1", "b"}, {"2", "c"}} here).






associations







share|improve this question











$endgroup$








  • 1




    $begingroup$
    Simply use Map, KeyValueMap or KeyMap?
    $endgroup$
    – Henrik Schumacher
    Dec 5 '18 at 19:20












  • $begingroup$
    Can you tell what exactly do you want to do?
    $endgroup$
    – Kuba♦
    Dec 5 '18 at 21:42










  • $begingroup$
    Woooops! Done! :)
    $endgroup$
    – SLesslyTall
    Dec 6 '18 at 7:40










  • $begingroup$
    @SLesslyTall You see, you want KeyValueMap[List] @ asso but who could've known :)
    $endgroup$
    – Kuba♦
    Dec 6 '18 at 7:53
















3












$begingroup$


How do you iterate over the keys or rules of an association (in any order)? E.g. for 



<|"0"->"a", "1"->"b", "2"->"c"|>


I would like to either iterate over "0", "1", "2" or tuples containing each key and value.



For example, something that performed the equivalent of a python dictionary's items, method would be ideal (which returns a list (or iterator) in the form [(key1, value1), ...], so {{"0", "a"}, {"1", "b"}, {"2", "c"}} here).






associations







share|improve this question











$endgroup$








  • 1




    $begingroup$
    Simply use Map, KeyValueMap or KeyMap?
    $endgroup$
    – Henrik Schumacher
    Dec 5 '18 at 19:20












  • $begingroup$
    Can you tell what exactly do you want to do?
    $endgroup$
    – Kuba♦
    Dec 5 '18 at 21:42










  • $begingroup$
    Woooops! Done! :)
    $endgroup$
    – SLesslyTall
    Dec 6 '18 at 7:40










  • $begingroup$
    @SLesslyTall You see, you want KeyValueMap[List] @ asso but who could've known :)
    $endgroup$
    – Kuba♦
    Dec 6 '18 at 7:53














3












3








3





$begingroup$


How do you iterate over the keys or rules of an association (in any order)? E.g. for 



<|"0"->"a", "1"->"b", "2"->"c"|>


I would like to either iterate over "0", "1", "2" or tuples containing each key and value.



For example, something that performed the equivalent of a python dictionary's items, method would be ideal (which returns a list (or iterator) in the form [(key1, value1), ...], so {{"0", "a"}, {"1", "b"}, {"2", "c"}} here).






associations







share|improve this question











$endgroup$




How do you iterate over the keys or rules of an association (in any order)? E.g. for 



<|"0"->"a", "1"->"b", "2"->"c"|>


I would like to either iterate over "0", "1", "2" or tuples containing each key and value.



For example, something that performed the equivalent of a python dictionary's items, method would be ideal (which returns a list (or iterator) in the form [(key1, value1), ...], so {{"0", "a"}, {"1", "b"}, {"2", "c"}} here).






associations




associations






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Dec 6 '18 at 7:40







SLesslyTall

















asked Dec 5 '18 at 19:15









SLesslyTallSLesslyTall

22317




22317








  • 1




    $begingroup$
    Simply use Map, KeyValueMap or KeyMap?
    $endgroup$
    – Henrik Schumacher
    Dec 5 '18 at 19:20












  • $begingroup$
    Can you tell what exactly do you want to do?
    $endgroup$
    – Kuba♦
    Dec 5 '18 at 21:42










  • $begingroup$
    Woooops! Done! :)
    $endgroup$
    – SLesslyTall
    Dec 6 '18 at 7:40










  • $begingroup$
    @SLesslyTall You see, you want KeyValueMap[List] @ asso but who could've known :)
    $endgroup$
    – Kuba♦
    Dec 6 '18 at 7:53














  • 1




    $begingroup$
    Simply use Map, KeyValueMap or KeyMap?
    $endgroup$
    – Henrik Schumacher
    Dec 5 '18 at 19:20












  • $begingroup$
    Can you tell what exactly do you want to do?
    $endgroup$
    – Kuba♦
    Dec 5 '18 at 21:42










  • $begingroup$
    Woooops! Done! :)
    $endgroup$
    – SLesslyTall
    Dec 6 '18 at 7:40










  • $begingroup$
    @SLesslyTall You see, you want KeyValueMap[List] @ asso but who could've known :)
    $endgroup$
    – Kuba♦
    Dec 6 '18 at 7:53








1




1




$begingroup$
Simply use Map, KeyValueMap or KeyMap?
$endgroup$
– Henrik Schumacher
Dec 5 '18 at 19:20






$begingroup$
Simply use Map, KeyValueMap or KeyMap?
$endgroup$
– Henrik Schumacher
Dec 5 '18 at 19:20














$begingroup$
Can you tell what exactly do you want to do?
$endgroup$
– Kuba♦
Dec 5 '18 at 21:42




$begingroup$
Can you tell what exactly do you want to do?
$endgroup$
– Kuba♦
Dec 5 '18 at 21:42












$begingroup$
Woooops! Done! :)
$endgroup$
– SLesslyTall
Dec 6 '18 at 7:40




$begingroup$
Woooops! Done! :)
$endgroup$
– SLesslyTall
Dec 6 '18 at 7:40












$begingroup$
@SLesslyTall You see, you want KeyValueMap[List] @ asso but who could've known :)
$endgroup$
– Kuba♦
Dec 6 '18 at 7:53




$begingroup$
@SLesslyTall You see, you want KeyValueMap[List] @ asso but who could've known :)
$endgroup$
– Kuba♦
Dec 6 '18 at 7:53










2 Answers
2






active

oldest

votes


















2












$begingroup$

To iterate over the keys of an association, first get the keys in a list using Keys. then use this in your favorite iteration construct (Do, Table, Scan, Map, etc):



In[16]:= assoc = <|"0" -> 0, "1" -> 1, "2" -> 2|>;



In[17]:= Do[Print[x], {x, Keys[assoc]}]



During evaluation of In[17]:= 0



During evaluation of In[17]:= 1



During evaluation of In[17]:= 2





share|improve this answer









$endgroup$





















    6












    $begingroup$

    If you would like to map over the keys to transform them into something else, you can use KeyMap:



    a = <|"0" -> 0, "1" -> 1, "2" -> 2|>;
    
a // KeyMap[("newKey" <> #) &]
    
(* <|"newKey0" -> 0, "newKey1" -> 1, "newKey2" -> 2|> *)


    Otherwise, the good old Map will iterate over the values as if the structure were a list:



    a // Map[("newVal" <> ToString@#) &]
    
(* <|"0" -> "newVal0", "1" -> "newVal1", "2" -> "newVal2"|> *)


    You should also look up KeyValueMap to see if that would make your task easier.



    Edit



    Henrik Schumacher's succinct comment contains everything I have elaborated here. His comment had not been posted when I began writing this answer.






    share|improve this answer









    $endgroup$













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      2 Answers
      2






      active

      oldest

      votes








      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      2












      $begingroup$

      To iterate over the keys of an association, first get the keys in a list using Keys. then use this in your favorite iteration construct (Do, Table, Scan, Map, etc):



      In[16]:= assoc = <|"0" -> 0, "1" -> 1, "2" -> 2|>;
      

      
In[17]:= Do[Print[x], {x, Keys[assoc]}]
      

      
During evaluation of In[17]:= 0
      

      
During evaluation of In[17]:= 1
      

      
During evaluation of In[17]:= 2





      share|improve this answer









      $endgroup$


















        2












        $begingroup$

        To iterate over the keys of an association, first get the keys in a list using Keys. then use this in your favorite iteration construct (Do, Table, Scan, Map, etc):



        In[16]:= assoc = <|"0" -> 0, "1" -> 1, "2" -> 2|>;
        

        
In[17]:= Do[Print[x], {x, Keys[assoc]}]
        

        
During evaluation of In[17]:= 0
        

        
During evaluation of In[17]:= 1
        

        
During evaluation of In[17]:= 2





        share|improve this answer









        $endgroup$
















          2












          2








          2





          $begingroup$

          To iterate over the keys of an association, first get the keys in a list using Keys. then use this in your favorite iteration construct (Do, Table, Scan, Map, etc):



          In[16]:= assoc = <|"0" -> 0, "1" -> 1, "2" -> 2|>;
          

          
In[17]:= Do[Print[x], {x, Keys[assoc]}]
          

          
During evaluation of In[17]:= 0
          

          
During evaluation of In[17]:= 1
          

          
During evaluation of In[17]:= 2





          share|improve this answer









          $endgroup$



          To iterate over the keys of an association, first get the keys in a list using Keys. then use this in your favorite iteration construct (Do, Table, Scan, Map, etc):



          In[16]:= assoc = <|"0" -> 0, "1" -> 1, "2" -> 2|>;
          

          
In[17]:= Do[Print[x], {x, Keys[assoc]}]
          

          
During evaluation of In[17]:= 0
          

          
During evaluation of In[17]:= 1
          

          
During evaluation of In[17]:= 2






          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Dec 5 '18 at 19:41









          Jason B.Jason B.

          48.1k388189




          48.1k388189























              6












              $begingroup$

              If you would like to map over the keys to transform them into something else, you can use KeyMap:



              a = <|"0" -> 0, "1" -> 1, "2" -> 2|>;
              
a // KeyMap[("newKey" <> #) &]
              
(* <|"newKey0" -> 0, "newKey1" -> 1, "newKey2" -> 2|> *)


              Otherwise, the good old Map will iterate over the values as if the structure were a list:



              a // Map[("newVal" <> ToString@#) &]
              
(* <|"0" -> "newVal0", "1" -> "newVal1", "2" -> "newVal2"|> *)


              You should also look up KeyValueMap to see if that would make your task easier.



              Edit



              Henrik Schumacher's succinct comment contains everything I have elaborated here. His comment had not been posted when I began writing this answer.






              share|improve this answer









              $endgroup$


















                6












                $begingroup$

                If you would like to map over the keys to transform them into something else, you can use KeyMap:



                a = <|"0" -> 0, "1" -> 1, "2" -> 2|>;
                
a // KeyMap[("newKey" <> #) &]
                
(* <|"newKey0" -> 0, "newKey1" -> 1, "newKey2" -> 2|> *)


                Otherwise, the good old Map will iterate over the values as if the structure were a list:



                a // Map[("newVal" <> ToString@#) &]
                
(* <|"0" -> "newVal0", "1" -> "newVal1", "2" -> "newVal2"|> *)


                You should also look up KeyValueMap to see if that would make your task easier.



                Edit



                Henrik Schumacher's succinct comment contains everything I have elaborated here. His comment had not been posted when I began writing this answer.






                share|improve this answer









                $endgroup$
















                  6












                  6








                  6





                  $begingroup$

                  If you would like to map over the keys to transform them into something else, you can use KeyMap:



                  a = <|"0" -> 0, "1" -> 1, "2" -> 2|>;
                  
a // KeyMap[("newKey" <> #) &]
                  
(* <|"newKey0" -> 0, "newKey1" -> 1, "newKey2" -> 2|> *)


                  Otherwise, the good old Map will iterate over the values as if the structure were a list:



                  a // Map[("newVal" <> ToString@#) &]
                  
(* <|"0" -> "newVal0", "1" -> "newVal1", "2" -> "newVal2"|> *)


                  You should also look up KeyValueMap to see if that would make your task easier.



                  Edit



                  Henrik Schumacher's succinct comment contains everything I have elaborated here. His comment had not been posted when I began writing this answer.






                  share|improve this answer









                  $endgroup$



                  If you would like to map over the keys to transform them into something else, you can use KeyMap:



                  a = <|"0" -> 0, "1" -> 1, "2" -> 2|>;
                  
a // KeyMap[("newKey" <> #) &]
                  
(* <|"newKey0" -> 0, "newKey1" -> 1, "newKey2" -> 2|> *)


                  Otherwise, the good old Map will iterate over the values as if the structure were a list:



                  a // Map[("newVal" <> ToString@#) &]
                  
(* <|"0" -> "newVal0", "1" -> "newVal1", "2" -> "newVal2"|> *)


                  You should also look up KeyValueMap to see if that would make your task easier.



                  Edit



                  Henrik Schumacher's succinct comment contains everything I have elaborated here. His comment had not been posted when I began writing this answer.







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered Dec 5 '18 at 19:25









                  ShredderroyShredderroy

                  1,5201115




                  1,5201115






























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