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
votes
2answers
390 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
268 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
900 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
votes
5answers
817 views

How to iterate over the columns of a Dataset?

I have a Dataset with a simple structure, like this: ...
8
votes
2answers
344 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
votes
1answer
341 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
votes
2answers
646 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
374 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
189 views
+50

Parsing Org-Mode Timelog Data

Suppose we have in ~/time-data/time-data.org the following data: ...
8
votes
3answers
184 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
votes
2answers
583 views

Creating a Stock Dataset

I've been looking into how to create a stock database in Mathematica using Dataset. This may or may not be a sensible idea, depending on the quantity of data required, although the possibility of ...
8
votes
1answer
3k views

How to convert a column of a Dataset into a list [closed]

I'm loving the fact that Mathematica has finally implemented the Dataset feature, but I'm still struggling a little with it. I have a Dataset that contains a bunch of functions for different diseases ...
8
votes
2answers
254 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
149 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
187 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
398 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
votes
1answer
209 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
votes
1answer
131 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
votes
1answer
132 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
votes
1answer
565 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
309 views

One ChartLegend for multiple charts in Dataset?

Dataset's documentation shows how to leverage GroupBy operator at multiple levels ...
8
votes
1answer
154 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: ...
8
votes
1answer
788 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
votes
0answers
56 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
510 views

Finding totals in a Dataset

I have this Dataset: ...
7
votes
3answers
945 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
216 views

Map Values in 'nested' association

JSON often returns sort of 'nested' associations like so: ...
7
votes
5answers
357 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 ...
7
votes
3answers
414 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: ...
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
329 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
371 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
463 views

How to read .npy file in Mathematica?

I have a .npy file which is created by numpy of Python as below:- ...
7
votes
2answers
269 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
375 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
1answer
146 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
777 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
887 views

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

I would like to transform a table like ...
7
votes
1answer
371 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
482 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
735 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
2answers
98 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
137 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 ...
7
votes
3answers
340 views

Enabling JoinAcross to merge non-joined keys

I've come across the following "JoinAcrossMerge" sufficiently often to wonder if Dataset's semantics can offer a natural implementation. Say I have 2 datasets (<...
7
votes
1answer
147 views

Why does an inert ReplaceAll modify this Dataset?

I cannot see any reason for this behavior besides a bug, but I've been wrong before so I put it before the community: ...
7
votes
1answer
119 views

KeyTake, KeyDrop fail with Transpose in Dataset

I think similar to unexpected-behavior-of-keytake there are other issues with v11.0 KeyTake and (more useful) KeyDrop that show ...
7
votes
1answer
277 views

Possible bug involving Dataset/Query and RightComposition

Bug introduced in 10.0.0 and fixed in 10.0.1 Short Version Why are the results of the following expressions different? ...
7
votes
3answers
405 views

Appending and Prepending columns to a dataset in 10.0.2.0

fixed in 10.1 (windows) I just experience a problem in prepending columns to a dataset. I did this a hundred times in 10.0.1.0 - no problems. Now it seems as if it is only possible to append/prepend ...
7
votes
1answer
209 views

JoinAcross Crashes Kernel in Version 11.0

Bug introduced in 11.0.0 and fixed in 11.0.1 The following executes without issue in 10.4.1 and returns immediately. However in 11.0 when the JoinAcross line is ...
7
votes
1answer
188 views

Writing code which generates a function to append many columns to a dataset

I love datasets in Mathematica. Say I have one that looks like this: ...