Iterate over keys of association











up vote
3
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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).










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  • 1




    Simply use Map, KeyValueMap or KeyMap?
    – Henrik Schumacher
    Dec 5 at 19:20












  • Can you tell what exactly do you want to do?
    – Kuba
    Dec 5 at 21:42










  • Woooops! Done! :)
    – SLesslyTall
    Dec 6 at 7:40










  • @SLesslyTall You see, you want KeyValueMap[List] @ asso but who could've known :)
    – Kuba
    2 days ago















up vote
3
down vote

favorite












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).










share|improve this question




















  • 1




    Simply use Map, KeyValueMap or KeyMap?
    – Henrik Schumacher
    Dec 5 at 19:20












  • Can you tell what exactly do you want to do?
    – Kuba
    Dec 5 at 21:42










  • Woooops! Done! :)
    – SLesslyTall
    Dec 6 at 7:40










  • @SLesslyTall You see, you want KeyValueMap[List] @ asso but who could've known :)
    – Kuba
    2 days ago













up vote
3
down vote

favorite









up vote
3
down vote

favorite











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).










share|improve this question















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






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share|improve this question













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share|improve this question








edited Dec 6 at 7:40

























asked Dec 5 at 19:15









SLesslyTall

22317




22317








  • 1




    Simply use Map, KeyValueMap or KeyMap?
    – Henrik Schumacher
    Dec 5 at 19:20












  • Can you tell what exactly do you want to do?
    – Kuba
    Dec 5 at 21:42










  • Woooops! Done! :)
    – SLesslyTall
    Dec 6 at 7:40










  • @SLesslyTall You see, you want KeyValueMap[List] @ asso but who could've known :)
    – Kuba
    2 days ago














  • 1




    Simply use Map, KeyValueMap or KeyMap?
    – Henrik Schumacher
    Dec 5 at 19:20












  • Can you tell what exactly do you want to do?
    – Kuba
    Dec 5 at 21:42










  • Woooops! Done! :)
    – SLesslyTall
    Dec 6 at 7:40










  • @SLesslyTall You see, you want KeyValueMap[List] @ asso but who could've known :)
    – Kuba
    2 days ago








1




1




Simply use Map, KeyValueMap or KeyMap?
– Henrik Schumacher
Dec 5 at 19:20






Simply use Map, KeyValueMap or KeyMap?
– Henrik Schumacher
Dec 5 at 19:20














Can you tell what exactly do you want to do?
– Kuba
Dec 5 at 21:42




Can you tell what exactly do you want to do?
– Kuba
Dec 5 at 21:42












Woooops! Done! :)
– SLesslyTall
Dec 6 at 7:40




Woooops! Done! :)
– SLesslyTall
Dec 6 at 7:40












@SLesslyTall You see, you want KeyValueMap[List] @ asso but who could've known :)
– Kuba
2 days ago




@SLesslyTall You see, you want KeyValueMap[List] @ asso but who could've known :)
– Kuba
2 days ago










2 Answers
2






active

oldest

votes

















up vote
2
down vote



accepted










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




























    up vote
    6
    down vote













    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





















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      2 Answers
      2






      active

      oldest

      votes








      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes








      up vote
      2
      down vote



      accepted










      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

























        up vote
        2
        down vote



        accepted










        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























          up vote
          2
          down vote



          accepted







          up vote
          2
          down vote



          accepted






          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












          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 at 19:41









          Jason B.

          47.5k387185




          47.5k387185






















              up vote
              6
              down vote













              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

























                up vote
                6
                down vote













                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























                  up vote
                  6
                  down vote










                  up vote
                  6
                  down vote









                  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












                  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 at 19:25









                  Shredderroy

                  1,4381115




                  1,4381115






























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