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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

Merge Associations and replace absent value with 0

I have two associations like this ...
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

List of Strings to Associations [closed]

I have a list of Strings, some thing like below: ...
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

Get values of Dataset in depth 2

Given the following dataset ...
3
votes
1answer
69 views

A calculation in two depth association

I have a dataset where values are associations too. ...
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
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

Select several values in nested associations

I have nested associations like this: ...
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"}: ...