# Find the values of the largest key of an association

I have an association:

1->{10,50,100}, 2->{2,4,6,9,60,90}, 3->{3,7,12,1425}, 4->{8,13,17,22,24,26,29}, 5->{18,23,27,32,97}, 6->{28,33,37,48,98}, 7->{38,78}, 8->{88}


I want to get the value of the largest key i.e. 8, from the above association i.e. 88. Is there a way to accomplish this?

• The function KeySort might also be notable in case you want to perform several of such iindexing by ordering of the keys; then you can order once a = KeySort[a] and access smallest and largest key by a[[1]] and a[[-1]] (and so on...) May 9, 2020 at 11:31

## 2 Answers

assoc = Association[1 -> {1, 5, 10, 50, 100},
2 -> {2, 4, 6, 9, 11, 15, 20, 40, 51, 55, 60, 90},
3 -> {3, 7, 12, 14, 16, 19, 21, 25, 30, 41, 45, 52, 54, 56, 59, 61,
65, 70, 91, 95},
4 -> {8, 13, 17, 22, 24, 26, 29, 31, 35, 42, 44, 46, 49, 53, 57, 62,
64, 66, 69, 71, 75, 80, 92, 94, 96, 99},
5 -> {18, 23, 27, 32, 34, 36, 39, 43, 47, 58, 63, 67, 72, 74, 76,
79, 81, 85, 93, 97},
6 -> {28, 33, 37, 48, 68, 73, 77, 82, 84, 86, 89, 98},
7 -> {38, 78, 83, 87}, 8 -> {88}];

assoc[Max @ Keys @ assoc]

{88}


Also

MaximalBy[First] @ assoc (* thanks: @swish *)

<|8 -> {88}|>

• MaximalBy works on associations, no need for Normal. May 9, 2020 at 10:48
• thank you @swish. Updated with your suggestion.
– kglr
May 9, 2020 at 10:52
Function[x, x@*Max@AssociationMap[Reverse][x]]@assoc


although I would use the method proposed by @kglr i.e.

assoc[Max @ Keys @ assoc]