Questions tagged [associations]
Questions on the associative data-structure introduced in Mathematica version 10.
520
questions
5
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2
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157
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A Nothing for Associations
In the same way that Nothing disappears from Lists, is there a built-in that when it appears as the value in an association the ...
- 5,314
0
votes
1
answer
43
views
How to organise definitions that contain named parameters
I have lots of definitions of (usually numeric) quantities that depend on parameters; they're mostly matrices (in the actual code, there are many more definitions):
...
- 205
1
vote
1
answer
55
views
Using an Association as a Manipulate variable?
I would like to use an association in a Manipulate or a DynamicModule.
Specifically, I'd like to click to change the Values of a list of Keys of an Association.
Here is some non-working code that (...
- 2,058
0
votes
0
answers
23
views
Carryover comments when merging Associations
I am tasked with merging several nested associations containing vast amounts of commented text. The merging itself is rather easy but all comments go missing and would have to be inserted manually ...
1
vote
1
answer
49
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Performance tuning joinAcross (my version)
I have written what I think is a more or less complete version of JoinAcross with code below. I've done this to try to avoid the misbehavior I've observed in the ...
- 572
0
votes
1
answer
71
views
Datasets in Mathematica [closed]
I have two columns of data as two separately defined lists. I want to create a dataset and assign a key to each column. I tried this:
...
- 5
5
votes
1
answer
51
views
Replacement of Association value does not evaluate
Cos[a - b] /. {a -> 0, b -> 0}
gives 1
However,
<|1 -> Cos[a - b]|> /. {a -> 0, b -> 0}
gives
...
- 15.6k
4
votes
3
answers
128
views
Change a group of values in a list of association
Noob here.
I want to change the value of all the keys "e", that meet my filter criteria ("c" and "d" are above or equal 20).
...
- 75
4
votes
1
answer
95
views
How to use ReplaceAll to create Association from List
I want to create a List of Associations from data in a two-dimensional List by using ...
- 199
3
votes
1
answer
120
views
Generic XML to Dataset
I am having trouble to transform XML data into a Mathematica Dataset of Associations. I want a dataset that follows the structure of the XML file with all its sublevels. Here is the example xml:
...
- 75
1
vote
3
answers
99
views
Self modifying association (in a search of "THIS" keyword)
Imagine we have the following structure (like a module)
...
- 115
0
votes
1
answer
80
views
How to create a dataset out of the entities?
I am working on learning how to create a dataset from a series of entities.
I have the following function that finds all properties of a certain entity:
...
- 1,037
0
votes
0
answers
32
views
-3
votes
1
answer
98
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How to find the distances to all buildings quickly?
I would like to create an association by mapping the function GeoDistance[Here,#]& over all buildings without missing locations in a reasonable amount of time less than 30 minutes.
I have the ...
- 1,037
5
votes
1
answer
123
views
0
votes
1
answer
58
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How to find all functions that accept level specifications as an argument?
How can I find a list of every function that takes a level specification as an argument?
- 1,037
1
vote
2
answers
80
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How to swap keys and values of an association? [duplicate]
How do you swap the values and keys of an Association in a manner similar to taking the transpose of a two-dimensional matrix or nested list?
I am trying to solve the Wolfram Challenge Capital Cities ...
- 1,037
3
votes
1
answer
46
views
Unexpected behavior with Derivative and a function parameters defined via an Association
I am confused by the following behavior:
...
- 339
18
votes
3
answers
487
views
Difference between HashTable datastructure and Association datastructure
Is there a difference in the runtimes between CreateDataStructure["HashTable"] and <||> in terms of inserting, ...
- 558
0
votes
2
answers
59
views
Add element to several associations automatically
I'm trying to add a certain element (testKey) to several already existing associations testAssoc1 and ...
- 3
1
vote
0
answers
67
views
How to work with structured data using graphs
Given that the functions for not only creating but also modifying Graph are functional programming creating copies it seems to me that it is a good idea to keep the vertices small, such as sticking to ...
- 271
1
vote
1
answer
79
views
How do I consider a list of items as a single atom when threading?
Suppose I have the following list of items:
...
- 8,085
3
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0
answers
74
views
Association vs Pattern Matching: which one is better for data storage?
Say I have a few key-value pairs. I can store them with Association as
...
- 655
4
votes
1
answer
89
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How to act with replacement on an association with syntax most similar to ReplaceAll
Replacements acting on Associations confuse me. I have read Pattern matching to a function evaluation inside an Association and How to use ReplaceAll and RuleDelayed with an Association? and I ...
- 3,553
1
vote
1
answer
61
views
Supplying options with an association [closed]
Let's say I have an association, like {"PlotStyle" -> Red}, and I want to use it to supply options to a function, such as ...
- 113
3
votes
1
answer
55
views
Converting Association to Matrix
Imagine I have the following association, where the keys are given as pairs of natural numbers
...
- 4,138
4
votes
1
answer
73
views
How can default valued be added in a Query?
I'm not understanding the the default values are not used to produced a length of 0 in the following example. What is the right way to add default values during a query?
...
- 12.3k
2
votes
1
answer
32
views
Changing Lists in Associations [closed]
On Mathematica 12.2 the code
x = <||>;
AssociateTo[x, "foo" -> {{1, 2}, {3, 4}}]
x["foo"][[1]] += {0, 1}
raises the error
Set::setps: ...
- 333
3
votes
0
answers
67
views
Representing and Extracting Properties of a System Product Breakdown Structure (a Directed Acyclic Graph)
I am trying to analyze products using a product breakdown structure (PBS), which is a directed acyclic graph (DAG) that reflects a decomposition of the product into subproducts, sub-sub-products, and ...
- 131
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votes
0
answers
67
views
AssociationMap with formatting
Build an Association using AssociationMap, where the keys are the letters of the Alphabet[] and the values are the same letters with the following Style:
The size of the letter should be set to twice ...
3
votes
1
answer
80
views
How can two objects be equal, but only one of them be a Key in my association
What is going on here? There is an element in Keys[Dat] which is equal to {2.1,2.1}, but ...
0
votes
2
answers
57
views
Selecting Keys when Lists are used as Keys
Analyzing a sequence after restructuring it, Counts returns a sequence similar to below:
...
- 1,024
2
votes
1
answer
61
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Mathematica association does not work on symbols
Question about using an association within Replace.
If I have an association which contains symbols like so:
...
- 74
0
votes
1
answer
84
views
Lists of labelled vectors, how to output a list of tuples which sum to zero
list = {{1, 1, 0}, {1, 0, 1}, {0, 1, 1}, {-1, 1, 0}, {1, -1, 0}, {-1, -1, 0}, {-1, 0, 1},
{1, 0,-1}, {-1, 0, -1}, {0, -1, 1}, {0, 1, -1}, {0, -1, -1}};
list2 = {{2, 0, 0}, {0, 2, 0}, {0, 0, 2}, {-2, ...
- 179
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votes
1
answer
58
views
How to merge or group an association by another association or rule?
I eat the following food over 3 days and track the calories. (Days indexed by 1,2,3)
...
1
vote
3
answers
67
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Merging associations other than zeros
I am importing different associations and wanting to merge them. An example of these associations are:
...
- 73
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votes
1
answer
54
views
Why is extracting values from an Association with 1 level slower than extracting values from a list of depth 1?
I am not looking for a solution or work-around, but an explanation.
Here are six examples of doing a trivial operation on an association and a list.
Initially, I was curious about the cost of calling ...
- 2,058
2
votes
0
answers
162
views
Lists of rules vs. Associations
It seems that generally, Mathematica users (or at least the Q&A I've read here) prefer associations to represent data in ways that many other languages would use structures.
However, when ...
- 2,177
4
votes
2
answers
68
views
Reduction of nested association based on criteria
I have a nested association of the following form:
...
- 113
1
vote
1
answer
101
views
How to merge two DateObject list together?
I have two huge lists of flight data(one is around 7 million observations and another is around 1 million).
The first one contains the city names, the departure time(accurate to the minute), and some ...
- 376
4
votes
1
answer
156
views
Better way to create a Dataset?
I'd like to create a Dataset from an array, where each column's heading becomes the key for all elements in that column. I can accomplish this using nested Table commands, but was wondering if there ...
- 3,446
3
votes
1
answer
52
views
Front end fails to represent correctly boxes
Context
Sometimes my front end misrepresents some output typically involving associations. For instance
EmbedCode[CloudDeploy["hello, world"]]
should ...
- 21.7k
7
votes
2
answers
176
views
Extract held value from Association
Consider an association which contains a key which must not be prematurely evaluated.
assoc = <| key :> value |>
For example, a value of ...
- 914
6
votes
4
answers
212
views
Sorting Associations by DayName (day of week) using KeySort and/or KeySortBy
I have an association where the keys are the days of the week:
...
- 3,446
11
votes
1
answer
172
views
Mysterious Intersection on Association
This bug has been fixed in version 13.0
I have try to do an intersection on list of associations and the result is astonishing. Here an example:
...
- 331
3
votes
1
answer
46
views
How to extract items from a LearnedDistribution object?
I have never understood how to use Cases to extract items from objects (other than exactly copying code written by others which, again, means I don't understand).
I ...
- 33.4k
1
vote
1
answer
44
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Fastest way to convert two associations into a sparse matrix
I have two association $N$ and $C$
$N$ has this form :
$N=<|x_1\rightarrow \{x_{1,1},...x_{1,p_1}\},x_2\rightarrow \{x_{2,1},...x_{2,p_2}\}...,x_D\rightarrow \{x_{D1},...x_{Dp_D}\} |>$
$C$ has ...
- 912
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votes
1
answer
60
views
Grouping dataset by tags
Here is a slight modificaiton of Mathematica's example dataset from the documentation:
...
- 2,470
2
votes
0
answers
54
views
Handling lists indexed with integer partitions
I am trying to do some exploration around the multi-dimensional version of [truncated moment problem], where I work with various distributions (uni- or multi-variate), and use some truncated moment ...
- 648
1
vote
1
answer
77
views
Redefining dot notation for Association
I'm trying to use Associations as object, and specifically want to use them as they are used in other languages using the dot notation.
I'm using the code below to get started.
...
- 1,007