Questions tagged [associations]

Questions on the associative data-structure introduced in Mathematica version 10.

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Updating a data table

1. Example data I have a data table organized as an Association of Associations: ...
eldo's user avatar
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2 answers
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Clip, Select, FirstPosition not working for extracting values from an association based on a range from another list

I have this dataset of associations: ...
atomic-muclei's user avatar
5 votes
5 answers
568 views

Analyzing football games (pairing matrix)

I want to cross-tabulate football games over several years. Setting up example pairings: Please note that there can be up to 20 clubs and a couple of thousand matches! ...
eldo's user avatar
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8 votes
6 answers
427 views

Accumulate up and down

I want to accumulate positive and negative values separately. dt = RandomSample[Range[-10, 10]] {3, -5, 2, -9, 1, -1, 0, 8, 10, 4, -7, 7, -8, -3, 6, -4, -2, 5, -10,...
eldo's user avatar
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5 votes
6 answers
322 views

Restrict sorting to a certain range

Example data (revised to include negative values - see comment of @ydd) ...
eldo's user avatar
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2 votes
2 answers
92 views

Move rows and columns of an association matrix

Example data: ...
eldo's user avatar
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3 votes
4 answers
208 views

Add missing column keys

Example data: data = {{"1", 50}, {"1", 60}, {"1", 40}, {"2", 15}, {"3", 18}, {"3", 18}}; The first ...
eldo's user avatar
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1 vote
1 answer
105 views

Speed Up Creating a List of Associations

Background I frequently import data from CSV files. This data often has headers, is a mix of numbers and text, and is a simple 2D 'shape'. I need to clean the data (eg removing rows, trimming strings, ...
IntroductionToProbability's user avatar
6 votes
3 answers
238 views

How do I reset the inner embedded key?

I have a Association: ...
yode's user avatar
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4 votes
3 answers
146 views

How to use key values as another plotting point

I have this list: ...
atomic-muclei's user avatar
0 votes
1 answer
58 views

Apply a function to a rectangular subgrid with missing values

Some example data: ...
eldo's user avatar
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2 votes
2 answers
69 views

Grouping and rejoining to original lists of associations

I am quite new to associations, and I have been stumbling multiple times over the same issue: I want to make calculations on a GroupedBy list of associations and ...
jabberwocky's user avatar
0 votes
0 answers
52 views

Plotting a list of associations on same plot and creating legends for each one

I have a list of associations that look like this and it goes on for more ts: ...
atomic-muclei's user avatar
5 votes
2 answers
267 views

Sorting with Missing values

I have the following data: ...
eldo's user avatar
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4 votes
2 answers
193 views

How to build a ranking matrix

I have the following Association: ...
eldo's user avatar
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8 votes
5 answers
417 views

Apply a function row- and columnwise

I want to a apply a function to the 2nd row and 2nd column of an association: ...
eldo's user avatar
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1 vote
0 answers
98 views

How to make the association's keys viewable by opener in input cell in editable form?

I have an association as follows (the actual association has hundreds of keys): ...
user13892's user avatar
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3 votes
1 answer
80 views

Two-dimensional associative array such as p["A"][[n]]

I am trying to use Associations in order to clean up / factorize my code but am still confused about how these work. In the code below, I have an object p which is 2-dimensional (or rather I am hoping ...
sg1234's user avatar
  • 269
4 votes
1 answer
90 views

How do I fill in these missing keys with empty strings to get a complete Dataset?

This is my original data: ...
yode's user avatar
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4 votes
4 answers
218 views

How to regroup elements of a cluster?

Given a clustering of unique elements, clustering = {{10, 40, 30}, {200, 500}, {6}, {7}, {8}}; How do I group a given subset of them into the same cluster? eg: <...
IntroductionToProbability's user avatar
12 votes
1 answer
422 views

Strange behaviour of an association

This an almost MWE of a problem I encountered when working with associations. asc1 = <| |>; asc1[1] = Range[0, 9]; asc1[2] = Range[0, 9]; asc1 Out[150]= <|...
Fred Simons's user avatar
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7 votes
2 answers
218 views

How to GroupBy or Gather on a nested association

I've been trying to figure out how to gather or group on a list of a nested associated--and flailing. Here is a reduced example. I'm interested in performance as the is for a larger example and the ...
Craig Carter's user avatar
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3 votes
1 answer
66 views

How to shorten the output of an Association

I'm writing a function that steps through a parameter and returns the outputs of NDSolve to make crude bifurcation diagrams. It seems like an ...
Chris K's user avatar
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4 votes
1 answer
78 views

On displaying association, including all items in a nice way?

Currently I use Dataset to display an association in a nice to see way on the screen. However, only top level items are shown this way. And have to click on each ...
Nasser's user avatar
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0 votes
1 answer
45 views

Having issues creating rules from a CSV import

I'm importing a CSV file with two columns. I've done this with other files, but this one is causing issues when trying to create rules to associate IDs with the titles. Here's a sample of the ...
Sam B's user avatar
  • 159
2 votes
0 answers
61 views

Is there a way to refer to the value of another key in the same association?

I have an association like below and want to know how to properly phrase the value for winner. in this example, the answer should be "a". ...
Indiana's user avatar
  • 321
2 votes
1 answer
44 views

How to equate the list elements to values list in a compact way?

Consider some list of keys keys={"1","2","3","4"} and the list of values ...
John Taylor's user avatar
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1 vote
1 answer
50 views

How to extract keys from the following definitions (not the standard association)?

Consider some example definitions: abba["1"] = 1; abba["2"] = 2; For some reason, I do not want to introduce the other form of representation ...
John Taylor's user avatar
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2 votes
2 answers
113 views

Is there a way to divide associations by key?

I have the following two associations <|A->2.02015,B->1.98025|> <|B->0.538000,A->0.462000|> I would like to produce a third association ...
Indiana's user avatar
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1 vote
0 answers
64 views

How to Name a Path in TemporalData?

Preamble: I am working with stock prices and need to perform calculations on them. And then extract the information for further calculations. TimeSeries/...
IntroductionToProbability's user avatar
0 votes
2 answers
33 views

Error when passing variable into Block and NumberForm

I made this pseudo-code that highlights what is happening. Assume the following dictionary: ...
Giovanni Baez's user avatar
1 vote
1 answer
141 views

How can I invert the association? [duplicate]

Consider an association assoc := Association[{"a" -> 1, "b" -> 2} ] How can I invert it, i.e., to obtain the following? ...
John Taylor's user avatar
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0 votes
0 answers
20 views

`Dynamic`caly change values of an association [duplicate]

Here are two attempts to make a slider that changes an value of an association. ...
Jineon Baek's user avatar
0 votes
2 answers
72 views

How to make multiple definitions in an elegant way?

Consider the following code: ...
John Taylor's user avatar
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3 votes
2 answers
125 views

How to create a GroupBy function that is better aligned with relational algebra?

I want a GroupBy function that behaves more in alignment with relational algebra principles. I can get what I want if I do it in 2 steps: Preparation: ...
Luxspes's user avatar
  • 918
6 votes
3 answers
292 views

Apply pattern using a Slot (#) to each list element using a second slot

I am trying to find a neat way of applying an operation to each list element, but do not know how to properly use multiple slots or whether it is actually possible to solve this with multiple slots. I ...
michelangelov's user avatar
1 vote
1 answer
100 views

Where does the result of thing["Properties"] come from?

Question I'll focus on the example stream=AudioStream@First@$AudioInputDevices I can do stream@"Properties" to get a ...
Adam's user avatar
  • 3,797
0 votes
3 answers
57 views

Efficient and compact replacement for Association in the following case

Consider the following association: ...
John Taylor's user avatar
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4 votes
1 answer
61 views

KeyReplace with text pattern

KeyReplace is a user added function that can be used to replace keys in associations. From the documentation: ...
Todd Dixon's user avatar
1 vote
1 answer
42 views

Replacement for Association in the following case

Consider the following three integrals: ...
John Taylor's user avatar
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2 votes
0 answers
48 views

Incoherence between `AssociateTo`/`KeyDropFrom` and `DownValues`

My version is 13.2 on Mac. When modifying association I find the following incoherences between AssociateTo/KeyDropFrom and <...
Lacia's user avatar
  • 2,183
1 vote
2 answers
88 views

Construct association depending on itself

I want to construct an association that some of the Values are constructed from other parts of the Values, for the simplest ...
Lacia's user avatar
  • 2,183
0 votes
0 answers
60 views

Long associations of short associations or the inverse, which one should I use?

I don't have enough experiences of using Association or Dataset, and when operating with nested associations I meet the ...
Lacia's user avatar
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1 vote
1 answer
115 views

How to update this Association?

I have the following association, assoc: ...
nilo de roock's user avatar
0 votes
1 answer
52 views

Why association slows down compiled function in the following example?

Consider the following code, which generates some data and performs some selections: ...
John Taylor's user avatar
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2 votes
2 answers
63 views

Pattern matching in Association fails in `Set` assignment

I want to define a symbolic-valued function using Set to memoize the result. However, I get different results when using an ...
Phro's user avatar
  • 131
1 vote
0 answers
94 views

Convert CSV to JSON

I'd like to convert some csv data to json. The CSV: ...
wmv's user avatar
  • 359
1 vote
1 answer
64 views

Permutations of Dataset

I have data with missing values. I need all permutations which follow the two rules: Every year must be represented in each draw; and each draw must contain a minimum of two elements for each year. ...
Rogo's user avatar
  • 790
1 vote
2 answers
54 views

Grouping Associations with varying lengths

I have a large dataset that comes to me in lists of four elements. Each list has a type, an identifying number, a year and a return. Here is a small sample What I need is a dataset in which the ...
Rogo's user avatar
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2 votes
1 answer
60 views

How do I compose a list from an Association such that the final product matches a fixed percentage of each of four subsets?

My question is in two parts. The first is about picking discrete elements inside a list of Associations to match a fixed percentage of a final sub-list; the second is about overcoming the rounding ...
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