Questions tagged [dataset]

Questions on the Dataset data type and related functionality introduced in version 10. Do not use for questions on data in more generic list format or data-manipulation questions generally.

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9
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1answer
193 views

How to FoldList over Dataset column without destroying/rebuilding Dataset?

I have a Dataset in the following form but with many more rows and a few other columns. ...
9
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1answer
185 views

Operator syntax for Merge-like Query

Bug introduced in 10.0.0 and fixed in 10.0.2 Is it possible to take advantage of Dataset's Query operator syntax to Merge parallel queries thereby avoiding Function's that are otherwise required? ...
9
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1answer
427 views

How do I 'Join' two Structured Datasets?

Consider the following Datasets dsCompetitions with fields {"id","name","eventTypeId"} dsEventTypes with fields {"id", "name"} I want to join the datasets as ...
9
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1answer
112 views

Export[…, “tsv”] drops minus signs from Dataset [horrific bug?]

Toy example: First, create a Dataset: ...
9
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1answer
281 views

Did 10.0.2 break some forms for named slots?

Bug introduced in 10.0.2 and fixed in 10.2.0 Since 10.0.2 some code that previously worked using named slots fail in very particular circumstances. Attchd screenshot shows the issue w/ a particular ...
9
votes
1answer
128 views

How can weighted averages be calculated for a Dataset summarized with GroupBy

I would like to compute market-value weighted stock prices grouped by sector from a Dataset but can't figure out how to apply ...
9
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1answer
195 views

Applying functions to irregularly distributed Keys in Association lists

This Q is related to this one, but now refer to the situation as irregularly distributed Keys in lists of Associations: ...
9
votes
1answer
119 views

JoinAcross datasets based on Equal and not on SameQ

JoinAcross will join keys if values are the same (SameQ==True) but not if there are equal. For example these two associations are not joined : ...
9
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1answer
155 views

What is Association[Rule[“ID”,number ] and how it is used?

I am trying to understand the structure and the use of Dataset and I came across something new to me. First check this example: ...
9
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1answer
634 views

Group dataset on two keys (GroupBy)

I would like to group the elements of row c of the following dataset according to the values in the columns a and b. That is Go from here To here And then I would like to print this on a grid, ...
9
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2answers
408 views

Median of Dataset in Mathematica 10

Bug introduced in 10.0 and fixed in 10.3 I'm having trouble calculating the median of a Dataset[] in Mathematica 10. The situation is as follows. Consider a ...
9
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0answers
287 views

How can I add column-rearrangement-by-mouse-dragging to my dataset display function?

A subject that I seem to take at heart... I was expecting an upgrade of the default Dataset display in MMA 10.3.1. It did not happen. Among the features I would have liked to see improved is a better/...
8
votes
5answers
947 views

How to extract points from a closed curve

OK, let's create a simple closed curve C0 = ContourPlot[x^2/4 + y^2/9 == 1, {x, -5, 5}, {y, -5, 5}]; and let's plot the corresponding points ...
8
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5answers
882 views

How to iterate over the columns of a Dataset?

I have a Dataset with a simple structure, like this: ...
8
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5answers
416 views

Group by multiple keys, merge at specific keys in dataset

I want to join associations in a dataset which share identical keys specified by the list sameAt and merge them by taking a Mean ...
8
votes
2answers
353 views

Cutting away points that are not resonances

My situation is as follows. I have a whole bunch of data that I need to fit, which tends to look like this picture: As can be seen, there's three dips (resonances) and a whole bunch of noise around ...
8
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3answers
448 views

Rearranging a Dataset

When processing a larger Dataset I came up do a point where I want to form a dataset with culumn heads from an intermediate structure. Here is an example of this structure: ...
8
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1answer
359 views

Transpose fail in 11.1 Dataset

The type system underlying Dataset seems a total kludge, as soon as one issue is fixed, here it recurs in a slightly different form - and difficult to isolate in minimal examples. Here's a failure ...
8
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2answers
686 views

Advanced SQL-type select statements (filtering) on Datasets

I'm trying to improve on mathematica's handling of datasets. I'm currently writing this function that should do the following. Suppose I have a dataset with columns, e.g. ...
8
votes
2answers
381 views

Dataset with no members

I am trying to plan a framework for relational algebra using the Dataset capability of Mathematica 10. In the work of Date and Darwen, there are two concepts known as TABLE_DEE and TABLE_DUM. ...
8
votes
3answers
191 views

Sum all columns from a list

I have a list of column names: list = {"col1", "col2", "col3"} and a dataset ds. I want to add a new column to ...
8
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2answers
277 views

Predict: How to customize model construction? (e.g. cross fold validation, mtry, number features used, ROC curve)

Question Overview In general this question is in regards to how to tweak the parameters used when one specifies a Method when calling the Predict function. Herein ...
8
votes
1answer
188 views

Datasets and Time Values: Filtering and Plotting

After struggling for a few weeks, I have accumulated a few examples of challenging date-related operatations with datasets. Some I have partial solutions; others I cannot yet do. The resources on ...
8
votes
1answer
201 views

Why are empty lists not consistently formatted in a Dataset?

A support case with the identification [CASE:3876977] was created. I just noted, that an empty list is not consistently formatted in a Dataset: ...
8
votes
2answers
446 views

How does Grid operate on Dataset?

The documentation (10.0.2) indicates that Grid can be used to display a Dataset; the section in guide/ComputationWithStructuredDatasets labelled 'Dataset Presentation'. However simply invoking Grid[...
8
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1answer
254 views

Operating on datasets that have been grouped based upon multiple criteria

I have a dataset tds that can be represented by the following code: ...
8
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1answer
141 views

Adding metadata to non-atomic expressions in Associations and Dataset

Information and Attributes require arguments to be symbols and strings , whether built in or user-defined. there's often the ...
8
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1answer
136 views

Can Mathematica Neural Net make use of the REC file format for images like MXNet?

When using large set of images for training neural networks (>10000, size 250 x 250 each) the time to read the images is quite long. My first approach was to use the DataSet functionality of ...
8
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1answer
133 views

How to do conditional coloring in dataset using new 12.1 functionality?

For the first part of this question consider the following dataset as an example: ...
8
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1answer
622 views

Dataset and string conversion, using Internal`StringToDouble

i'm trying to get familiar with the new Dataset-stuff in Mathematica 10. As it will (hopefully) provide some benefit for me, I have started to convert my app to move from list and list of rules to ...
8
votes
1answer
318 views

One ChartLegend for multiple charts in Dataset?

Dataset's documentation shows how to leverage GroupBy operator at multiple levels ...
8
votes
1answer
850 views

How can I export `Dataset` to a standard format?

I work with big data on AWS and scientific data in all the standard formats such as these... Is there any way to Import/Export Datasets or Associations to any of these non-primitive (txt, csv, json......
8
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0answers
57 views

Operating on a dataset named “data” triggers an error message [duplicate]

Update: With thanks to the editor, it was made clear to me that this is due to a bug in some packages autoloaded during some operations on Dataset expressions. Nothing to do with the name of the ...
7
votes
4answers
575 views

Finding totals in a Dataset

I have this Dataset: ...
7
votes
3answers
975 views

Normal // Association // Dataset workaround for some user query operators

Given example tabular data (ie, with rows and columns, or "data frames") ...
7
votes
2answers
222 views

Map Values in 'nested' association

JSON often returns sort of 'nested' associations like so: ...
7
votes
3answers
1k views

Display ALL keys in dataset

I created a dateset (estimates) with 25 keys (my columns), and about a hundred rows. I'd like to be able to list the keys from the dataset. I did this: ...
7
votes
1answer
397 views

Export of (large) Dataset lasts very long

I have a Dataset (non numerical data) which has a ByteCount of about 14GB, When I export it to disc (SSD) the resulting ".m" or "...
7
votes
2answers
378 views

10.0.2 another Dataset type system (inference?) warning

Bug introduced in 10.0.2 The warning below seems unrelated to these issues: Did 10.0.2 break some forms for named slots? and 10.0.2 mapping Association to Dataset warning. First noticed w/ ...
7
votes
2answers
282 views

How to access Dataset's metadata

A Dataset object has internal metadata. For example, let ds = Dataset[{<|"a" -> 1, "b" -> "x", "c" -> {1}|>}]; ...
7
votes
2answers
378 views

Transpose can't handle fractions

Bug introduced in 10.0 and fixed in 10.2.0 Note: Dataset and Association are new in 10.0 Related to this question, why can't <...
7
votes
2answers
764 views

SemanticImport mis-interprets CSV

SemanticImport misinterprets rows with trailing blanks. Note the commas in the 2nd column: SemanticImport["https://docs.google.com/spreadsheet/pub?key=0Ati-...
7
votes
1answer
134 views

In Wolfram Mathematica, who do I query the result of a Counts operation efficiently and conveniently?

Setup Say, I'm given a dataset, like the one below: titanic = ExampleData[{"Dataset", "Titanic"}]; titanic Answering with: And I want to count the occurrences ...
7
votes
1answer
151 views

How to show Histogram axes or frame in v11 Dataset?

Is there a way to show Histogram (and related plots) axes or frames in v11 Dataset? ...
7
votes
1answer
942 views

How would I use Map on a Dataset column?

I am somewhat new to functional programming. To improve the performance of a package, I would like to re-write a package in a functional style. I have the following ...
7
votes
1answer
963 views

Transform a table (list of associations) to a flat association

I would like to transform a table like ...
7
votes
1answer
375 views

Incorrect result while using SemanticImport for CSV file import

I might use this incorrectly. I want to use a .csv file that (as list) looks like: ...
7
votes
3answers
497 views

AssociationMap to query Dataset across levels?

Is there a way to operate on Dataset across levels to apply a function f to a key -> value pair in an Association as follows: ...
7
votes
2answers
110 views

Creating a new Dataset column using a map from a second Dataset

Say I have two datasets: one is a detailed list of events, and one is a coarse list of events. I want to add a column to the detailed list from the coarse list (for the purposes of sorting). For ...
7
votes
2answers
157 views

Associations of List is not printing properly in mathematica 11

<|"i1" -> {a11, a12, a13}, "i2" -> {a21, a22, a23}, "i3" -> {a31, a32, a33}|>//Dataset The above code produces the following where rows are still ...

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