Questions tagged [associations]
Questions on the associative data-structure introduced in Mathematica version 10.
10
votes
3answers
272 views
Min and Max of a list of Associations
I am trying to find the minimum values for all elements in a list of associations, below is an example
...
3
votes
2answers
141 views
Iterate over keys of association
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 ...
2
votes
3answers
63 views
3
votes
1answer
32 views
KeySelect via Not[StringMatchQ[Pattern]] fails
I have an Association asc that has mixed type Keys:
...
0
votes
1answer
81 views
Aggregate function problem
I use a function to do something similar to a SQL sum. I've asked about simplifying it in another post. I'm still using this function and it works well for aggregates like ...
5
votes
1answer
54 views
unexpected result from augmented assignment to association
Is the last of these results expected? If so, how?
...
9
votes
1answer
71 views
Parallelize[MapIndexed[…,Association[…]]] returns broken result
Bug introduced in 10.0.2 or earlier and persisting through 11.3
Confirmed: CASE:4041910
Consider the following example:
...
2
votes
1answer
95 views
Parallelize the construction of sparse matrices
I'm trying to parallelize a few constructions of chain complexes (given as a list of sparse matrices). I have a function that for any column (or row) computes the list of nonzero entries in that ...
1
vote
0answers
37 views
Extracting Parts of Speech
I am looking to parse the ConstituentsTree from TextStructure.
Someone already asked how to get the proper nouns out of a text here:
Extract names from a document
I am looking for a more general ...
4
votes
2answers
82 views
speedy update of list of associations
Suppose as is a list of associations that I want to update.
For example:
...
11
votes
3answers
236 views
Convert List of Associations into Association of Lists
For neural networks mathematica likes 2 ways to structure training sets:
...
3
votes
2answers
121 views
Merge associations with the same keys, same in a sense by user's definition
I know that it is the standard functionality of Merge to combine the values of the same keys among associations.
Now I would like to deal with a situation in which,...
6
votes
2answers
75 views
GraphDistance error when Graph vertices are Associations
Bug introduced in 10.0 or earlier and persisting through 11.3
Here is a nice graph whose vertices are Associations:
...
2
votes
1answer
39 views
Filter rows in nested Association / Dataset using Select
The Dataset I am working with has the following nested structure.
...
1
vote
1answer
66 views
Converting a list of associations into a single association
How do i smartly join a List of Associations (eg. returned by ParallelTable) such that i get a single Association?
...
6
votes
2answers
96 views
How to use ReplaceAll and RuleDelayed with an Association? [duplicate]
I expected that something like this
...
6
votes
1answer
78 views
How can I update an association with a function?
I'm not sure if this is a bug, or if I just am not understanding, properly, how to create a function.
I am able to use a list of rules to update an association like so:
...
7
votes
2answers
185 views
How can I map associations to expressions?
I have a list of associations, and I would like to make it so that an expression automatically reads the associated data from the associations list, that has the same name, into the expression. An ...
8
votes
2answers
229 views
Deleting all keys that have null values
I have a notebook that I am working on that starts with an imported CSV file. Many of the rows have blank data in them. I have used the following command to establish a list of associations:
...
5
votes
3answers
158 views
ByteCount on Function
I was comparing RAM and CPU efficiency for List, Rule, Association, Function. The following code
...
1
vote
1answer
113 views
How to make an Association of Assocations [closed]
As a learning exercise I’m trying to convert some data we have from spreadsheets into an association of associations. However, I’ve only managed to format two different associations, a key of the ...
11
votes
1answer
113 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
21 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
111 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
66 views
6
votes
1answer
82 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
41 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
93 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
46 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
33 views
3
votes
1answer
69 views
1
vote
1answer
71 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
91 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/...
2
votes
0answers
25 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
30 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
45 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
165 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
45 views
Export & Import Association with Lists and Rationals without ExpressionJSON
Consider following association:
...
2
votes
0answers
64 views
Lookup in Association [closed]
I have some issues with the Lookup in Association. My association looks as:
...
1
vote
1answer
80 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
115 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
97 views
4
votes
4answers
151 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
40 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
82 views
`ListPlot` with `Association` as input
It seems ListPlot will somehow drop the trailing list of Associations when the Association ...
0
votes
1answer
53 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
57 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
143 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
67 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
204 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"}:
...
