Is there any way to map a list of elements to a dictionary without a loop?










1















I want to create 2 dictionaries by mapping 2 lists from a central dictionary, without using a loop.



Input dictionary:



edict_all = 1:[[23,20]], 2:[[45,45]], 3:[[56,43]], 4:[[66,23]], 5:[[24,23]], 9:[[57,78]], 8:[[67,76]], 51:[[242,223]]


And I have 2 lists:



list_a = [1,4,8,9,51]
list_b = [1,2,3,5,9]


Currently, I am using 2 for loops:



edict_a, edict_b = dict(), dict()
for i in list_a:
edict_a[i] = edict_all[i]

for i in list_b:
edict_b[i] = edict_all[i]


And the output is:



edict_a = 1: [[23, 20]], 4: [[66, 23]], 8: [[67, 76]], 9: [[57, 78]], 51: [[242, 223]]

edict_b = 1: [[23, 20]], 2: [[45, 45]], 3: [[56, 43]], 5: [[24, 23]], 9: [[57, 78]]









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  • Not aware of a way to get what you are looking for without python looping through the values. There are lots of ways to get what you want with list or dict comprehensions as well as built-in functions that may not have the appearance of the looping approach you are using (and may be more efficient) but in fact are all looping through the data.

    – benvc
    Nov 14 '18 at 16:24
















1















I want to create 2 dictionaries by mapping 2 lists from a central dictionary, without using a loop.



Input dictionary:



edict_all = 1:[[23,20]], 2:[[45,45]], 3:[[56,43]], 4:[[66,23]], 5:[[24,23]], 9:[[57,78]], 8:[[67,76]], 51:[[242,223]]


And I have 2 lists:



list_a = [1,4,8,9,51]
list_b = [1,2,3,5,9]


Currently, I am using 2 for loops:



edict_a, edict_b = dict(), dict()
for i in list_a:
edict_a[i] = edict_all[i]

for i in list_b:
edict_b[i] = edict_all[i]


And the output is:



edict_a = 1: [[23, 20]], 4: [[66, 23]], 8: [[67, 76]], 9: [[57, 78]], 51: [[242, 223]]

edict_b = 1: [[23, 20]], 2: [[45, 45]], 3: [[56, 43]], 5: [[24, 23]], 9: [[57, 78]]









share|improve this question
























  • Not aware of a way to get what you are looking for without python looping through the values. There are lots of ways to get what you want with list or dict comprehensions as well as built-in functions that may not have the appearance of the looping approach you are using (and may be more efficient) but in fact are all looping through the data.

    – benvc
    Nov 14 '18 at 16:24














1












1








1








I want to create 2 dictionaries by mapping 2 lists from a central dictionary, without using a loop.



Input dictionary:



edict_all = 1:[[23,20]], 2:[[45,45]], 3:[[56,43]], 4:[[66,23]], 5:[[24,23]], 9:[[57,78]], 8:[[67,76]], 51:[[242,223]]


And I have 2 lists:



list_a = [1,4,8,9,51]
list_b = [1,2,3,5,9]


Currently, I am using 2 for loops:



edict_a, edict_b = dict(), dict()
for i in list_a:
edict_a[i] = edict_all[i]

for i in list_b:
edict_b[i] = edict_all[i]


And the output is:



edict_a = 1: [[23, 20]], 4: [[66, 23]], 8: [[67, 76]], 9: [[57, 78]], 51: [[242, 223]]

edict_b = 1: [[23, 20]], 2: [[45, 45]], 3: [[56, 43]], 5: [[24, 23]], 9: [[57, 78]]









share|improve this question
















I want to create 2 dictionaries by mapping 2 lists from a central dictionary, without using a loop.



Input dictionary:



edict_all = 1:[[23,20]], 2:[[45,45]], 3:[[56,43]], 4:[[66,23]], 5:[[24,23]], 9:[[57,78]], 8:[[67,76]], 51:[[242,223]]


And I have 2 lists:



list_a = [1,4,8,9,51]
list_b = [1,2,3,5,9]


Currently, I am using 2 for loops:



edict_a, edict_b = dict(), dict()
for i in list_a:
edict_a[i] = edict_all[i]

for i in list_b:
edict_b[i] = edict_all[i]


And the output is:



edict_a = 1: [[23, 20]], 4: [[66, 23]], 8: [[67, 76]], 9: [[57, 78]], 51: [[242, 223]]

edict_b = 1: [[23, 20]], 2: [[45, 45]], 3: [[56, 43]], 5: [[24, 23]], 9: [[57, 78]]






python python-3.x list dictionary mapping






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edited Nov 14 '18 at 17:14









jpp

102k2164115




102k2164115










asked Nov 14 '18 at 15:15









Gurpreet.SGurpreet.S

626




626












  • Not aware of a way to get what you are looking for without python looping through the values. There are lots of ways to get what you want with list or dict comprehensions as well as built-in functions that may not have the appearance of the looping approach you are using (and may be more efficient) but in fact are all looping through the data.

    – benvc
    Nov 14 '18 at 16:24


















  • Not aware of a way to get what you are looking for without python looping through the values. There are lots of ways to get what you want with list or dict comprehensions as well as built-in functions that may not have the appearance of the looping approach you are using (and may be more efficient) but in fact are all looping through the data.

    – benvc
    Nov 14 '18 at 16:24

















Not aware of a way to get what you are looking for without python looping through the values. There are lots of ways to get what you want with list or dict comprehensions as well as built-in functions that may not have the appearance of the looping approach you are using (and may be more efficient) but in fact are all looping through the data.

– benvc
Nov 14 '18 at 16:24






Not aware of a way to get what you are looking for without python looping through the values. There are lots of ways to get what you want with list or dict comprehensions as well as built-in functions that may not have the appearance of the looping approach you are using (and may be more efficient) but in fact are all looping through the data.

– benvc
Nov 14 '18 at 16:24













2 Answers
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1














Loops at some level are unavoidable here, but you can hide them with zip and operator.itemgetter:



from operator import itemgetter

edict_a = dict(zip(list_a, itemgetter(*list_a)(edict_all)))
edict_b = dict(zip(list_b, itemgetter(*list_b)(edict_all)))





share|improve this answer






























    0














    You can use Python generator expression to filter data and then pass it back to dict() constructor:



    edict_a = dict((key, value) for key, value in edict_all.items() if key in list_a)
    edict_b = dict((key, value) for key, value in edict_all.items() if key in list_b)


    And yes, loops in any form are unavoidable for this problem. At least you can write it in one line.






    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









      1














      Loops at some level are unavoidable here, but you can hide them with zip and operator.itemgetter:



      from operator import itemgetter

      edict_a = dict(zip(list_a, itemgetter(*list_a)(edict_all)))
      edict_b = dict(zip(list_b, itemgetter(*list_b)(edict_all)))





      share|improve this answer



























        1














        Loops at some level are unavoidable here, but you can hide them with zip and operator.itemgetter:



        from operator import itemgetter

        edict_a = dict(zip(list_a, itemgetter(*list_a)(edict_all)))
        edict_b = dict(zip(list_b, itemgetter(*list_b)(edict_all)))





        share|improve this answer

























          1












          1








          1







          Loops at some level are unavoidable here, but you can hide them with zip and operator.itemgetter:



          from operator import itemgetter

          edict_a = dict(zip(list_a, itemgetter(*list_a)(edict_all)))
          edict_b = dict(zip(list_b, itemgetter(*list_b)(edict_all)))





          share|improve this answer













          Loops at some level are unavoidable here, but you can hide them with zip and operator.itemgetter:



          from operator import itemgetter

          edict_a = dict(zip(list_a, itemgetter(*list_a)(edict_all)))
          edict_b = dict(zip(list_b, itemgetter(*list_b)(edict_all)))






          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Nov 14 '18 at 17:13









          jppjpp

          102k2164115




          102k2164115























              0














              You can use Python generator expression to filter data and then pass it back to dict() constructor:



              edict_a = dict((key, value) for key, value in edict_all.items() if key in list_a)
              edict_b = dict((key, value) for key, value in edict_all.items() if key in list_b)


              And yes, loops in any form are unavoidable for this problem. At least you can write it in one line.






              share|improve this answer



























                0














                You can use Python generator expression to filter data and then pass it back to dict() constructor:



                edict_a = dict((key, value) for key, value in edict_all.items() if key in list_a)
                edict_b = dict((key, value) for key, value in edict_all.items() if key in list_b)


                And yes, loops in any form are unavoidable for this problem. At least you can write it in one line.






                share|improve this answer

























                  0












                  0








                  0







                  You can use Python generator expression to filter data and then pass it back to dict() constructor:



                  edict_a = dict((key, value) for key, value in edict_all.items() if key in list_a)
                  edict_b = dict((key, value) for key, value in edict_all.items() if key in list_b)


                  And yes, loops in any form are unavoidable for this problem. At least you can write it in one line.






                  share|improve this answer













                  You can use Python generator expression to filter data and then pass it back to dict() constructor:



                  edict_a = dict((key, value) for key, value in edict_all.items() if key in list_a)
                  edict_b = dict((key, value) for key, value in edict_all.items() if key in list_b)


                  And yes, loops in any form are unavoidable for this problem. At least you can write it in one line.







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered Nov 14 '18 at 18:10









                  Andrey SemakinAndrey Semakin

                  153211




                  153211



























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