Questions on the associative data-structure introduced in Mathematica version 10.
11
votes
1answer
78 views
stable sort for association?
Should I be able to use the "list of functions" approach to getting a stable sort of an association? In 11.1 I see,
...
0
votes
1answer
16 views
how to get association from json? [closed]
How do I convert {{"a" : 13, "z" : 24},{"f" : 17, "h" : 94}} to get
{{"a" -> 13, "z" -> 24},{"f" -> 17, "h" -> 94}}
I am trying to change : to ->
3
votes
3answers
87 views
Simpler way to thread dataset values to each other
I have a relatively simple dataset that provides a list of values for a list of countries:
...
0
votes
1answer
62 views
5
votes
1answer
64 views
How to update values of particular keys efficiently
Say I have a list of Association,
SeedRandom[45]
test = Association[Table[i -> RandomInteger[30], {i, 6}]]
<|1 -> 18, ...
1
vote
1answer
40 views
How to draw DensityPlot on a given association? [closed]
I want to draw a DensityPlot similar to below:-
DensityPlot[Sin[x] Sin[y], {x, -4, 4}, {y, -3, 3}]
But my problem is, I am not given the function itself. I am ...
5
votes
1answer
81 views
Replace value in association data-set
I have an association dataset with a depth of two (each value is an association too, and the size of the dataset ~ 30000 keys and an average size of values are ~2000 keys association). The dataset ...
1
vote
1answer
39 views
Selecting nonzero rules from a list
I have a list of rules: list = {a1 -> 0, a2 -> 3x, a4 -> 0, a5 -> 5x+3...}.
I would like to append to another list the nonzero rules, which are: ...
1
vote
1answer
31 views
3
votes
1answer
63 views
1
vote
1answer
65 views
Why do I need a second Function in SortBy for Association?
I cannot understand why I need a second pure function when trying to sort Association by Key. Here is an example
...
3
votes
1answer
84 views
Associations & generating training sets
Solution: Pi is allowed in training sets, but not in batches generated by the batch generating function
preamble:
I want to generate my own batches of training data for training a deep CNN.
ref/...
1
vote
0answers
22 views
Keyed eigensystem for nested Association
Suppose a matrix is given where both rows and columns are keyed, for example this correlation matrix:
...
1
vote
1answer
21 views
Button doesn't work with Append [duplicate]
I have a extremely simple question on Button. I tried to append values to associations. The Append works good with given value outside button, but once it is inside Button, it doesn't append the value ...
2
votes
1answer
41 views
Handling Missing values flexibly in Query (MissingBehavior problem)
There’s an inconsistency in how Missing values are imputed in Query, with ...
6
votes
2answers
159 views
Average length (in words) of paragraphs in document
I try to calculate the average length (in words) of paragraphs in a document. The data look like:
...
0
votes
0answers
32 views
Export & Import Association with Lists and Rationals without ExpressionJSON
Consider following association:
...
2
votes
0answers
55 views
Lookup in Association [closed]
I have some issues with the Lookup in Association. My association looks as:
...
1
vote
1answer
64 views
Dynamically update of Association
I try dynamically to add new keys and update the values of existing keys in given dataset (Association). I implement this by the following code:
...
2
votes
3answers
113 views
Using Association[] in an Immediate Function
I have an Association[] which is the result of an intensive computation. Its values include the variable x and I would like to ...
1
vote
2answers
84 views
1
vote
4answers
122 views
How can I create an Association from a multidimensional list of values and a list of keys?
Given a list of values such as
vals = {{{{0., 633.25}, {642.96, 677.34}}, {{591.56, 632.45}, {634.9, 715.6}}}}
and a list of "Dimensions" such as
...
1
vote
0answers
37 views
Create Association from Expression
I have a set of algebraic expressions of a certain form, and I would like to make them into Associations in a specified way. My expressions are formed of two heads, ...
2
votes
2answers
75 views
`ListPlot` with `Association` as input
It seems ListPlot will somehow drop the trailing list of Associations when the Association ...
0
votes
1answer
37 views
Flatten table into Association Thread where each cell is an association from its column and row header
Let's say I have a table in Mathematica like so:
Where the first row is the header, and first column is also a header (similar to a multiplication table). ie S_AS_A = Es; S_BS_A = ss_sigma;
The ...
4
votes
1answer
55 views
How can I get Merge to indicate missing values?
Say I have the following code:
Merge[{<|"a" -> 1, "b" -> 2|>, <|"a" -> 2, "c" -> 3|>}, Identity]
The output is:
...
8
votes
2answers
133 views
Timing: extracting from List VS extracting from Association
I was wondering, why is extracting from an Association slightly faster than extracting from a List?
...
2
votes
2answers
65 views
Building a replacement rule from a pattern, Assocation and RuleDelayed [duplicate]
I'm trying to create a function that builds a replacement rule from a given pattern and I have trouble understanding what's going wrong.
After having written most of the question, I see that it got ...
5
votes
4answers
198 views
Fastest way to look up in a list of Associations
Given a list of associations tab where each association has keys {"name", "a", "b"}:
...
4
votes
2answers
142 views
Creating a large surjective dictionary without repeated elements?
I would like to have a surjective dictionary that saves the following associations
...
3
votes
4answers
72 views
Cross-Rearranging parts of nested lists inside list of associations
I have list of associations like this:
...
1
vote
1answer
51 views
Extracting the graph of Keys in nested Associations
Related to this q: Extract all Values from nested Association
How to extract the direct graph of all Keys in nested Associations...
1
vote
0answers
55 views
1
vote
1answer
45 views
Plotting an association key corresponding to the maximum value
I have an Association <|0->q^2, 1->2p q, 2->p^2|>, where q=1-p.
I would like to plot the key (0, 1 or 2) ...
3
votes
1answer
58 views
Rename Keys in Nested Association
I am looking to expand this post, How can a key be renamed in an Association?.
I would like a function that automatically replaces any and all keys with the rule.
Here is what I have so far
...
3
votes
0answers
36 views
Missing values vanish from expressions with DateObject and slot-lookup?
Missing value vanishes when adding or subtracting DateObject but only when slot-lookup is used, in an Association query:
Given
...
7
votes
1answer
73 views
Association lookup in sub-kernel seems slow
While developing a parallel version of some code, I noticed that looking up an item in an association seemed much slower than in the serial version of the code.
To show the effect, I created the ...
5
votes
2answers
128 views
How to set parts of Associations “named with” SubValues
Parts of Associations can be set with the following syntax:
as = <|"a" -> 10|>
<|"a" -> 10|>
as["b"] = 20;
as
...
4
votes
3answers
125 views
Dataset query for keys of upper levels
Say I have a Dataset like this:
dat=Dataset[<|"a" -> 2, "b" -> "y", "c" -> {2, 3}|>]
I want to get the keys of upper levels as elements in the ...
5
votes
3answers
116 views
Changing deep parts of expression specified by complex query
asso = <|"x" -> {
<|"a" -> 5, "b" -> "y", "c" -> {5, 6, 7}|>,
<|"a" -> 6, "b" -> "z", "c" -> {}|>}
|>
I want to ...
7
votes
1answer
120 views
0
votes
0answers
36 views
How to pass var to Select[(#colunm == value) &] construct [duplicate]
I'm using a construct (more complex in fact as the value_ should take a list) to select some entries from an association with criteria:
...
7
votes
2answers
193 views
6
votes
1answer
161 views
24
votes
1answer
443 views
Bug with Block & Lookup: Scope Variable Leak
After debugging a large chunk of code, I could identify this MWE.
...
4
votes
3answers
99 views
Pretty print of Association with Format, how to?
I have some assocations, containing a lot of data, lets say something like
<|"x"->{... big list ...},....|>
I would like to print these associations in ...
4
votes
0answers
58 views
how to count or extract Cases out of list of association that matches pattern
I have list of associations
...
4
votes
0answers
122 views
Extract a key from an Association?
I have some large nested expression containing associations and I'd like to extract the nth key inside one of them, using part syntax.
Here's a tiny example:
...
2
votes
1answer
48 views
TakeLargestBy nested variable in Dataset
I would like to TakeLargestBy a nested variable in a Dataset. To be clearer, here is code to make an example dataset
...
4
votes
1answer
69 views
Merging unevaluated key/values
RuleDelayed is a supported key/value wrapper in Associations.
What are general guidelines/idiomatic methods for working with ...
