Questions on using or implementing more or less common data structures such as linked lists, structs, trees, tries, heaps etc. in Mathematica.

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0answers
2 views

Short way to query Dataset by the value of several columns

I learned how to query Dataset for rows that contain a certain value, but now I need to query for a long series of And in chain ...
22
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2answers
343 views

Dataset vs an association of associations

Associations with a record structure (e.g., a flat table) can be organised in one of two main ways. First as a list of associations, which is also used in the case of Mathematica's data set ...
1
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0answers
60 views

Custom Head for Encapsulation

Often when I'm writing a project in Mathematica, the number of arguments I must provide to functions spins out of control. I need a sort of object-oriented encapsulation approach. I've already had a ...
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0answers
101 views

Integration of graphs with datasets

Mathematica has a rich family of graph algorithms. I would like to leverage some of these for a very large tree structure. Because of the size of the structure, I would like to store it in a Dataset ...
2
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0answers
46 views

AVL binary search tree implementation

Is there any text-book implementation of self-balancing binary search trees such as AVL or red-black in Mathematica?
17
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1answer
202 views

Why do lookup times in Dataset and Association differ by orders of magnitude?

Consider the following three data structures: a list of rules, an association, and a dataset: ...
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1answer
58 views

Import and export without changing number format

I have a complex file that is the output of a program. The file contains multiple columns with data in different number formats. For example: ...
3
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0answers
82 views

Does Mathematica support an unordered set (e.g. hashset) data structure?

Does Mathematica support any data structure representing an unordered set (without multiplicity) of Mathematica expressions? I would like this data structure to support $O(1)$ insertion, deletion, and ...
2
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0answers
48 views

Does Mathematica support out-of-core Associations?

I often find myself collecting data in an Association[] which outgrows my computer's main memory. Does Mathematica support any out-of-core equivalent? Ideally, I ...
2
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2answers
165 views

Entropy of the elements of a general data set

I have the following data set, and wish to track the evolution of the entropy of each element within the set. I have evaluated the entropy for some elements, but how does one evaluate the entropy of ...
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0answers
51 views

combining separate data into pairs after reading from excel so I can run regression

I have the following code that reads data from an excel spreadsheet: ...
3
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4answers
112 views
2
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1answer
110 views

ordered tree data structure

I have a map $f:X\to \mathbb{N}$ and I wish to find $x,x'\in X$ such that $f(x)=f(x')$. Since such elements are rare, I will have to check very many elements and perform many comparisons, so I suspect ...
4
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1answer
108 views

Parsing string with nested information

I am trying to parse a string, but I have no idea how to solve the following problem ...
5
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2answers
212 views

How would I programmatically add a row to a Dataset?

I would like to use a Dataset to track the process of a lengthy calculation over a large volume of material. Dataset appeals to me because of the power of the queries and it also looks like it may ...
4
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1answer
111 views

Filtering Query Nested Data (Dataset and Association)

I am trying to filter a nested Dataset. I have some data that looks like this (curated for this example): ...
3
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2answers
245 views

Mathematica data structures for analysis [closed]

I'm starting to learn Mathematica and one thing that has been bugging me is the apparent lack of a good structure for keeping data and metadata for analysis. Something along R's ...
2
votes
1answer
123 views

Structure of KernelMixtureDistribution and SmoothKernelDistribution

I would like to know more about the structure behind the KernelMixtureDistribution and SmoothKernelDistribution in Mathematica. ...
21
votes
1answer
266 views

Make my data-structure atomic

Lately, and by lately I mean since version 7 or so, the number of atomic expressions in Mathematica constantly grew. In former times only the native types like integers and optimised arrays were ...
0
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1answer
72 views

Right data format when EmpiricalDistribution expects “Rectangular Array”

I have the following code to generate random data (these are the eigenvalues of a non-central Wishart matrix, and I am interested in their distribution). ...
1
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1answer
148 views

ReadList or any other command to read in blocks of very large numbers

I have a data file, data.txt, having following data: ...
14
votes
1answer
215 views

Why won't SparseArray let me store values with the head List?

When you attempt to define a SparseArray with elements that have the head List it complains: ...
3
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3answers
187 views

Breaking up combined data into several smaller data sets

I have one combined data with first number as the x-value and the remaining as different y-axis values (y1,y2,y3...). How do I break this combined list, data= (x,y1,y2,y3...) into smaller lists, such ...
11
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0answers
352 views

Learning Resources for Data Science in the Wolfram Language

I'm delivering an upcoming course on Data Science with the programming/analysis done predominantly in the Wolfram Language. I created the following table to leverage students' familiarity with Lists ...
13
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3answers
590 views

Converting hierarchies of rules to associations

The impossibility of MatchQ-ing inside and Association MatchQ-ing Associations (MMA 10) explains a problem I have. I would like ...
3
votes
1answer
329 views

how to create Dataset after importing txt file

I would like to translate a imported txt file to Dataset. ...
0
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4answers
141 views

Using levels in MapIndexed

I am trying to use MapIndexed to manipulate a matrix of data but I am having trouble getting the levels parameter to work the way I would like. Suppose that my data ...
25
votes
3answers
963 views

Error changing Dataset using Part

Update It was a bug in the documentation of V10.0, this functionality was not implemented yet, and V10.1 changed the documentation, removing it. It's a pity, because it's a very useful operations, ...
89
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3answers
4k views

How to make use of Associations?

I have been curious about it for long. Now that Mathematica 10 arrives, I think it's time to ask the question: How the new Association data structure would be used ...
1
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0answers
127 views

What's a non-trivial Mathematica program involving conscious choice of stack vs. queue data structure?

In a typical computer science algorithms course, much attention is given to the discussion of queues vs. stacks as a data structure programmers need to consciously choose from to achieve algorithmic ...
35
votes
2answers
2k views

How can I add a column into a existing Dataset?

I'm very excited about the brand new Dataset function. I have played with it in Wolfram Cloud, and haven't figured out how can I add a new column into an existing ...
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0answers
70 views

Data structures sought for storing particular list information

I have a set of lists. These lists contain two dimensional coordinates of natural numbers. So a list can be ...
1
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1answer
68 views

DownValues Type Access and Timing

I definitely use so much DownValues structure for some many applications like to replace some common structures in a some way. It seems that DownValues is so fast for access, and set. My question is ...
2
votes
2answers
116 views

Extracting “records” from a matrix

From a rank 3 matrix like ...
4
votes
2answers
685 views

What is the Mathematica way of joining two tables?

Is there a special Mathematica way of joining tables of data together, so that I would get similar functionality as if I was running a database with sql? For example, I have one particular table ...
2
votes
2answers
788 views

Get positions of all non zero matrix elements

I want to find all non zero elements of a table and I want to create a list that contains the name of the table the element was removed from, the position of the element, and the value of the element. ...
0
votes
1answer
99 views

Matrix Operation

I have a $3\times3$ matrix A, and a function sTrans that outputs two $3\times3$ matrices in a list when given a $3\times3$ ...
2
votes
1answer
779 views

Interpolation: Unstructured grid error

If I try to make a table SimpleTable and to interpolate a function of two variables, I encounter a problem. For example: ...
2
votes
3answers
348 views

Re-arranging / selecting of a data table very slow in For loop [duplicate]

My task is quite simple; I have a table of data like M = {{1,2}, {1,3}, {3,4}, {5,1}, {6,9}, {6,8}, {6,1}}; so the table is sorted with respect to the first ...
3
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1answer
149 views

Reading many single files and creating numbered (? or indexed) variable

I tried many different approaches, but I could not solve the following problems, I appreciate your help: What is the best way to read many data files? I mean we have ...
2
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0answers
65 views

Autoupdate Section Numbers? - Technical Document Authoring with Mathematica

Technical document authoring systems are structured ways to create, manage, and update documentation for various mediums such as print, pdf, web, etc. Take a look at this technical document ported to ...
6
votes
1answer
159 views

Return struct from function (with DownValues)

In Mathematica there is a way to create struct-like data type: struct[myField]=value I want to return myStruct from a function: ...
2
votes
1answer
120 views

Distances of locations in the matrix form

I want to have the distances of the cities in the matrix form.How can I have it for example for the cities like followings that also includes the distance of the city from itself which is zero: ...
16
votes
2answers
603 views

Efficient priority queues?

I'm trying to figure out how to transfer the concept of a priority queue to the functional world. Searches have turned up some implementations that use Append and other expense list copying ...
11
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3answers
3k views

Implementing a dictionary data structure

As one learns from a course on data structures, hash maps or dictionaries can be efficient when applied to appropriate tasks. I need a hash map in Mathematica and I've never found it. I'm scratching ...
1
vote
0answers
71 views

Efficiently generating 3D histograms for large sets 2D coordinates [duplicate]

I'm attempting to generate a 3D histogram for a large set of two-dimensional coordinates ($\approx 10^7$). the x- and y-components of each coordinate are rounded to the nearest integer, and these ...
1
vote
2answers
873 views

Import Spreadsheet Data and DeleteCases of empty cells &/or choosing a Range to import

I am importing Excel spreadsheet data into Mathematica. Here is what the data looks like, notice the cell Q1 with "sdf": I import this data by specifying the Spreadsheet location, sheet name, top ...
2
votes
1answer
114 views

Mean of Date variable data

I have hourly registered data as : ...
5
votes
1answer
189 views

Error in ARIMAProcess example

I am trying to compile the sample of ARIMAProcess of MMA here .It doesn't work.What is wrong?Could you please help?I am using exact same code. ...