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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41
votes
2answers
3k 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 ...
65
votes
6answers
10k 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 <...
36
votes
1answer
653 views

Visualizing Type System Operations

With the introduction of Dataset in version 10, Mathematica acquired a static type-checking subsystem. A fair number of dataset-related questions here on MSE ...
36
votes
5answers
3k views

Show More Rows of Dataset

Dataset rather conveniently truncates the display of a dataset that has many rows. However, occasionally, I would like to show more of a dataset without having to ...
38
votes
4answers
2k 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, ...
34
votes
5answers
2k views

Mathematica 10 Dataset doesn't format more than 4 columns?

Try this code in Mathematica 10: Dataset@Table[Association[ToString[#] -> # & /@ Range[4]], {2}] I got a nicely formatted table: But when I do the same ...
15
votes
3answers
518 views

Deleting noisy data from a plot (manually) and export the best remaining data

I have the following temperature time-series. As you can see it contains very very noisy points in some periods (Fig.A). I tried to approach the best data(the black one in the center) based on the ...
13
votes
1answer
339 views

Streaming`LazyList`Testing may have a leak

Bug introduced in 10.2 and fixed in 10.3 Version 10.2; Win64 Enterprise. I'm seeing this message... data::shdw: Symbol data appears in multiple contexts {Streaming`LazyList`Testing`, Global`}; ...
11
votes
4answers
3k views

Join two datasets on keys

I want to be able to join two datasets by keys, pretty much like I'd do in SQL. I thought the JoinAcross function might do it, but it doesn't operate the way I thought. The example in the ...
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 ...
11
votes
2answers
221 views

Lookup with default broken in Dataset

Given an Association, ...
8
votes
1answer
200 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: ...
7
votes
1answer
280 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? ...
15
votes
5answers
2k views

GroupBy several keys while keeping the Dataset as a Table (List of Associations)

Assume you import data from a Table source of the following format. ...
12
votes
2answers
1k views

Import iTunes xml data and convert it into a dataset or table

I have an xml file with song data from iTunes (https://dl.dropboxusercontent.com/u/1012958/iTunes%20Library.xml) and I'd like to import it to Mathematica to do some statistics. I get an XMLObject like ...
19
votes
3answers
925 views

Applying different functions to different columns of a Dataset

Suppose I have different functions: Total, Mean and Max and the following ...
13
votes
1answer
376 views

10.0.2 mapping Association to Dataset warning

Bug introduced in 10.0.2 and fixed in 10.0.3 In 10.0.2 ExampleData[{"Dataset", "Titanic"}][All, <| "gender" -> #sex|> &] Outputs the expected ...
19
votes
3answers
2k views

Assign names to Dataset columns

I am constructing a dataset like so: data = Dataset[AssociationThread[Keys[characterCounts], charFrequencies]] which gives me a dataset that looks like this: ...
16
votes
2answers
1k views

Change Values in Dataset under Condition

I have the following Dataset: ...
16
votes
2answers
716 views

Can't get Append to append a record (association) to a dataset

Bug introduced in 10.0.0 and fixed in 10.1 or earlier The Documentation Center item, Computation with Structured Datasets, implies that Append has been extended in ...
13
votes
3answers
388 views

Dataset collapsing/reducing

I have a dataset ds with 3 columns named A, B, C. Columns A and B have repeated values. How can I obtain another dataset that contains a list of the values in C for ...
12
votes
2answers
247 views

Missing: KeyGroupBy?

Especially in tree-structured data, keys and values, being two sides of the same coin, frequently interchange roles. The ability to aggregate by value but not by key upsets the balance. How to ...
19
votes
2answers
369 views

Dataset seems to break Information

Bug introduced in 10.0 and fixed in 11.0.0 Dataset is new in 10.0 Note: In order to reproduce the bug, the symbol Dataset may ...
11
votes
2answers
845 views

How to merge Datasets representing matrices with named rows/columns?

I am working with square (non-symmetric) matrices with named rows and columns. The data I receive is sometimes messy and rows/columns may come in various permutations. I usually need to semi-...
9
votes
0answers
280 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/...
4
votes
1answer
648 views

Using Datasets in Mathematica 10.0

Bug introduced in 10.0 and fixed in 10.1 I am trying to use the Dataset functionality which was introduced in Mathematica 10.0 : ...
19
votes
1answer
1k views

best practices for saving Datasets and TemporalData to a SQL database

I have been working with a simulation tool that generates large volumes of data, and it's time to start saving this to a proper database. Is there an established mechanism for saving TemporalData ...
52
votes
2answers
2k views

User interface Mathematica 12.1 terribly slow

I installed Mathematica 12.1 a few days ago and now I experience a serious speed slow down. When working with datasets for example Mathematica is close to be unusable. Even in the help systems it ...
20
votes
1answer
836 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 ...
18
votes
1answer
2k views

How to split a Dataset into training and testing for machine learning?

Suppose I have iris data In the Dataset Format. How to split the iris data Into training and testing for Machine learning? For example,Transform the data for Classify.
14
votes
2answers
895 views

How to work with a Dataset?

I have an application for which a Dataset appears useful. I want a structured dataset which consists of a set of records, which are presumably Associations. For the data set, I would like to be able ...
14
votes
5answers
2k views

Append a list as a column in a dataset

I have a Dataset and a List, called dataset and intervals, and I would like to append the list as a new column of the dataset. I ...
17
votes
7answers
1k views

How to search Dataset to find all keys share same Value

If I have the following Dataset ...
13
votes
5answers
520 views

Dataset Processing: efficient ways to clean and merge sets for Life Sciences

Dataset Processing (for Life Sciences) Note: a related, but distinct task is posted here ID Swapping: Efficient use of a reference table to convert ID values. A common task, at least for me, ...
12
votes
5answers
2k views

Export a simple DataSet with key-value associations to CSV in Mathematica 10

I'm trying to Export a simple dataset with key-value pairs to a CSV Export["n.csv", MyDataset, "CSV"] This results in a single-line serialization: ...
11
votes
1answer
182 views

Odd StringTake problem in Dataset

Bug introduced in 10.0 and fixed in 10.4 Dataset is new in 10.0 10.2 Win64 Works fine... ...
10
votes
1answer
1k views

Converting structured data to a dataset [duplicate]

A Dataset seems perfect to represent structured data. Has anyone already thought about how to convert as efficiently/elegantly as possible an XML or JSON file to a Dataset in Mathematica 10 ?
7
votes
3answers
965 views

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

Given example tabular data (ie, with rows and columns, or "data frames") ...
12
votes
2answers
337 views

Query datasets with “variable” named slots

I want to query a Dataset object, e.g. select some entries using ...
11
votes
1answer
287 views

10.0.2 breaks a recursive “trie” query

Bug introduced in 10.0.2 and fixed in 10.2 The 10.0.2 Dataset type system complication breaks a recursive trie constructor that worked in 0.1: ...
10
votes
1answer
193 views

Problems with Dataset's querying on a fresh Kernel

Bug introduced in V10.4.1 or earlier and fixed in V11.3 A support case with the identification [CASE:3710757] [...] I checked and reproduced the issue at my end and have reported the issue to ...
9
votes
2answers
401 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
votes
3answers
294 views

Problem constructing Association tables with some operators

fixed in 10.0.2 First, set up the example Dataset from the documentation: titanic = ExampleData[{"Dataset", "Titanic"}]; Why ...
8
votes
1answer
616 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 ...
6
votes
2answers
209 views

DeleteMissing level spec confusion

Given: titanic = ExampleData[{"Dataset", "Titanic"}] Why does this correctly delete Missing[] elements: ...
4
votes
1answer
298 views

Replace Elements in a Dataset by rules

I've got a dataset with 100+ various columns. I want to change e.g. the values 0 and 1 in the first column with "male" and "female". In the second column i'd like to change the 0 and 1 with e.g. "...
9
votes
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: ...
7
votes
3answers
416 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 ...
6
votes
1answer
179 views

Explaining error when using Part inside Module in Dataset

I have a vague recollection of seen an explanation for this, but I can not find it, so it may be a false memory. Will delete if duplicated. Let ds be a simple <...
3
votes
1answer
995 views

Applying a function to a column of a dataset [closed]

Functions can easily be applied to columns of datasets, as in the documentation it is shown. Now I want to apply a function with parameters to a column, but I get a list rules. E.g. ...