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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6
votes
4answers
241 views

Average dataset with many repetitions?

I have a dataset where each item is of the form: <|"p1" -> x1, "p2" -> x2, "r1" -> y1, "r2" -> y2|> The interpretation is this: ...
4
votes
0answers
66 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 ...
17
votes
0answers
121 views

V10's TypeSystem - what are these function useful for? [closed]

The symbols in the TypeSystem` context are clearly used for working with Datasets, but they seem powerful. I was hoping that someone could help explain how they work and is they are useful for ...
3
votes
0answers
63 views

Map level inconsistencies with Missing values [closed]

Negative Level specs interact with Missing values, eg: ...
8
votes
2answers
95 views

A subtlety in Query

Let us consider a simple Dataset: ds=Dataset[{<|"a"->12,"b"->4|>,<|"a"->7,"b"->8|>,<|"b"->3|>}] Column "b" is easy to find: ...
3
votes
0answers
68 views

Data Interpolation of deaths by date

I am working with an ebola dataset from Guinea, 2014:(http://currents.plos.org/outbreaks/article/estimating-the-reproduction-number-of-zaire-ebolavirus-ebov-during-the-2014-outbreak-in-west-africa/). ...
3
votes
2answers
107 views

With “named row” nested Datasets: How to Select or Filter rows by row key with criteria from another Dataset?

After some calculations and grouping I have a Dataset similar to the following form: ...
1
vote
0answers
45 views

How to show complete dataset? [duplicate]

<|{{1, "u"}, {1, "u"}} -> {{0}}, {{1, "d"}, {1, "u"}} -> {{2 (f - g Cos[p])}}|> // Dataset gives All the items are incomplete. How to show ...
3
votes
1answer
84 views

How to get name of “named row” in Dataset for function applied to each row

After some calculations and a GroupBy I have a Dataset that is structured like this. ...
4
votes
2answers
103 views

Remove rows from dataset using query

MyDataSet[Select[#point[Fsr] == 1 &]] returns the row I want to delete, now I am trying what looks to me the most logic command to remove these rows, which is ...
1
vote
1answer
66 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 ...
3
votes
1answer
50 views

Blocking Dataset`$ElisionThreshold doesn't work

I would like to define a simple function to automatically show all rows in a Dataset. Based on Taliesin Beynon's answer, I tried the following trivial snippet: ...
7
votes
1answer
103 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: ...
4
votes
1answer
82 views

Getting error message with Search on arXiv electronic preprint database

Just installed Mathematica v10.3 which has the new option to use arXiv, the electronic database. However I get an error message using ...
3
votes
1answer
83 views

DeleteMissing doesn't match in Association tables

DeleteMissing doesn't work in Association tables: ...
11
votes
1answer
144 views

The equivalent of dplyr mutate with Dataset

In R, there is a package "dplyr" that works on data.frame objects, which is one of the origins of the Mathematica Dataset construct. One of the things dplyr can do is "mutate" the columns of a ...
7
votes
5answers
513 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 ...
6
votes
2answers
108 views

Query datasets with “variable” named slots

I want to query a Dataset object, e.g. select some entries using ...
3
votes
0answers
101 views

Best practices with HDF5 and Datasets

I work with colleagues who rely on HDF5 as their data interchange format (largely exported from Python's Pandas). Of course we ...
28
votes
4answers
1k views

How can I import a huge CSV file quickly?

I have two CSV files, each one is around 1 GB of data. When I use Import["file.csv"], it takes a very, very, long time to import the data. So how can I accelerate ...
3
votes
0answers
98 views

Dataset fails to present data in some instances when inserting new data

Update: I solved the problem: the error will occur when the length of an association is less than the length of the longest association in the association of associations In my original problem I ...
1
vote
2answers
130 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 ...
2
votes
2answers
61 views

Converting data set from one form to another

I wish to convert Data to Data2. Both sets are provided below. Note that the second set has an arbitrary parameter "t". How can this be done. ...
5
votes
1answer
122 views

How to analyze all the data in a directory

I am trying to import, analyze, and save all the .txt files in a specific directory. I can do this with a single .txt file using the following code: ...
12
votes
1answer
267 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 ...
8
votes
0answers
53 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 ...
4
votes
0answers
39 views

Why this shadowing when dealing with a dataset? [duplicate]

I have a dataset which I use as "dsall" and a function keylist (just for my convenience, nothing spectacular): ...
1
vote
0answers
44 views

Custom drop-down list of tags for Dataset Keys similar to CountryData

CountryData produces a drop-down list of tags when you enter a string. I would like to replicate this functionality for a ...
4
votes
0answers
109 views

Convert .csv Dataset and store in Databin [closed]

Trying out the new Databin product in the Wolfram Cloud. I have a simple ,-delimited .csv file with a header row which I have imported using the follwing: ...
12
votes
1answer
205 views

How does Dataset compare to DataFrame in pandas?

Pandas is a Python package providing fast, flexible, and expressive data structures designed to make working with “relational” or “labeled” data. Just like ...
24
votes
1answer
322 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 ...
18
votes
2answers
287 views

Dataset seems to break Information

Bug present in version 10.2 My little function, from pre-10.2 ,to turn a headed table into a Dataset. ...
9
votes
2answers
108 views

Using Merge[Identity] and Transpose on a Dataset

While experimenting with this answer, I ran across the following: ...
10
votes
1answer
126 views

Odd StringTake problem in Dataset

10.2 Win64 Works fine... Dataset[{<|"a"->"ABC"|>}][All, StringTake[#a,{1,3}]&] Explicitly taking the whole string using its length directly. ...
7
votes
1answer
182 views

Converting a Table to a Dataset

I feel like this is a simple task, and there may be a built in method to doing this (but I can't find it if there is). I would like to be able to take a table and convert it into a structured Dataset. ...
13
votes
1answer
258 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`}; ...
4
votes
1answer
55 views

Hold[Dataset[__]] not holding

With Hold[Dataset[Random[]]] instead of an expected Hold[Dataset[Random[]]] Can ...
18
votes
2answers
354 views

10.2 Dataset extraneous print using Transpose

Bug introduced in 10.2 and fixed in 10.2 (by paclet update GeneralUtilities 10.2.1) This is probably patch code in 10.2. Is there a way to turn off print with ...
23
votes
2answers
531 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 ...
0
votes
1answer
59 views

How to Export a mixture distribution to .json file

I would like to export the following mixture distribution mathematica found for my dataset to .json file ...
15
votes
2answers
312 views

Exporting Dataset to WDX format fails

I reported this to WRI support. Tracking number is CASE:3368636 Official answer is: Thank you for contacting Wolfram Technical Support. This is a known issue and our developers are working on a ...
4
votes
1answer
124 views

Query Dataset to check if row contains any from a set of values

For a given keyless dataset, I can query to return the rows whose columns contain a specific value. For example: ...
8
votes
5answers
314 views

How to iterate over the columns of a Dataset?

I have a Dataset with a simple structure, like this: ...
7
votes
2answers
210 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 ...
5
votes
2answers
103 views

Dataset breaks multi-character StringSplit

Given ds = Dataset[{"a b", "c-d"} ] multi-character StringSplit is broken with Dataset ...
11
votes
2answers
154 views

Lookup with default broken in Dataset

Given an Association, ...
7
votes
2answers
209 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 ...
4
votes
0answers
97 views

Why is Transpose Dataset slow in one direction

Transpose is faster when it distributes Keys at the 2nd level of a Dataset than when it factors them out. ...
4
votes
1answer
130 views

ANOVA test on dataset

I have a dataset with 3 groups and two variables. I want to do ANOVA test on the three groups for each variable. Does anyone know how to do this? ...
3
votes
0answers
61 views

Export to MX seems to corrupt the in-memory Dataset

I have a function that does a large number of calculations (by calling out to other smaller functions), and then builds a large Dataset object. Then I do two ...