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Results tagged with associations
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user 19542
Questions on the associative data-structure introduced in Mathematica version 10.
3
votes
Can association be used to find the maximum key less than a specific number?
I believe this is of higher order than you are looking for but it works with an Association.
Max@Select[Keys[assoc], # <= 10 &]
(* 7 *)
Keys gets the keys, Select grabs those less than equal to 10, …
- 43.2k
2
votes
Attempting to modify parts of a multi-level association in-place
You can create/assign a key/value directly by using the resetting values syntax.
m2 = <|"M" -> <|1 -> {1, 2, 3}, 2 -> {2, 3}|>, "F" -> <|1 -> {}, 2 -> {}|>|>;
m2["M"]["b"] = 3;
m2
(* <|"M" -> <|1 - …
- 43.2k
4
votes
Apply function to nested associations
MapAt[MatrixForm, test, {{"correlation"}, {"descendants", "correlation"}}]
If "descendants" contains a list of Associations then {"descendants", All, "correlation"} instead.
Hope this helps. …
- 43.2k
1
vote
Is there a way to order elements in an Association?
You may use Query and Select.
Query[Select[Between[{0, 3}]@Length@# &] /* SortBy[Length]]@assoc
<|F14->{},F17->{},F3->{},F66->{},F19->{S51},F20->{S51},F32->{S51},F35->{S51},F39->{S51},F41->{S51},F …
- 43.2k
8
votes
Why association pattern unmatched when using variable
You may use KeyValuePattern.
With
assoc = <|id -> 6, dur -> 10, skill -> 1, succ -> {7}, dl -> 250|>;
last = 7;
then the following return True.
MatchQ[assoc, KeyValuePattern[succ -> {___, last, ___}] …
- 43.2k
3
votes
Short way to query Dataset by the value of several columns
If you have your $\{column, value\}$ pairs in a list
findList = {{"x1", myX}, {"x2", myX}, {"x3", myX}, {"x4", myX}};
then you can build the Select criteria function from it.
selectCriteria[find_L …
- 43.2k
4
votes
Get association element that has a parameter
You can Select from the Keys of the Association the elements with Head equal to second and then pick out the parameter from second.
Select[Head@# === second &]@Keys[assoc] /. second[p_] -> p
(* {para …
- 43.2k
1
vote
Aliases for keys?
It seems you have already done it with Alternative.
c = <|"Major" | "Maj" -> {0, 4, 7}, "Minor" | "Min" -> {0, 3, 7}|>;
You would just need KeySelect and MatchQ.
KeySelect[MatchQ[#]@"Major" &]@c
…
- 43.2k
3
votes
Accepted
Applying KeyDrop to a String Pattern
If you have also have strings that are not words you may use DictionaryWordQ.
assoc = <|000 -> 2, .60 -> 1, .04348 -> 1, "able" -> 1, "24km" -> 3|>;
KeySelect[assoc, Quiet[DictionaryWordQ[#, IgnoreCa …
- 43.2k
4
votes
Function like KeyMap that combines values in case of key collisions
You may use Query to improve performance.
ClearAll[keyCombine];
keyCombine[fun_, asc_?AssociationQ, comb_ : Identity] :=
asc //
Query[Normal /* GroupBy[fun@*Keys]] //
Query[All, (Values@# &) /* …
- 43.2k
0
votes
Joining two datasets if second is association of associations
You could alter the GroupBy to return the structure you desire.
dReduced =
d[
GroupBy["id"]
/* Values
, Transpose
/* Query[{"id" -> First, Sequence @@ Thread[Range[2, 3] -> Total]}]
/* …
- 43.2k
16
votes
How to organically merge nested associations?
It automatically inserts nested associations where they do not exists and does not need to be assigned back to the original association. It updates existing keys when they are found. …
- 43.2k
2
votes
Min and Max of a list of Associations
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 AssociationTh …
- 43.2k
4
votes
How can I join some values in rows to be value columns in a dataset/association
dat = Dataset@KeyUnion@associations
Now with GroupBy a single hierarchical Dataset can be created. …
- 43.2k
7
votes
Merge two database with a common key
You may use JoinAcross with Dataset or Association. I show with Dataset below. To perform with Association remove the Postfix and Dataset from dsCompounds and dsProperties. Also, you may find the Ch …
- 43.2k