Questions tagged [query]

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53 views

Generating Google BigQuery API Access Token in Wolfram Language

I'm working on a Wolfram Language Package to connect into Google Bigquery (that I'll make public available). In order to finish It, I need to solve a last step, that is how to get an authentication ...
4
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2answers
83 views

Using subquery in Query of Dataset

I want to create a Query to a Dataset that will select a subset of three columns, modify the date column in this subset (to month), group by month and a second column (location), take the group means ...
5
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1answer
146 views

How can I understand this example of Query taken from current Mathematica documentation?

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0answers
54 views

Is there a documented meaning for the following Query syntax?

Consider this example: ...
2
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0answers
56 views

Efficiently get positions of Query results

I have some very large Datasets. Is there any efficient method of getting the positions of results found in a Query? That is, without using ...
4
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1answer
63 views

A simple way to extract information from this dataset with Query?

I have a dataset comparable to the following (you may wrap it in Dataset if you like). I am looking for a relatively simple way to query it and extract information. ...
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0answers
31 views

Can the following operation be performed in a single query without using explicit Maps or nesting Queries?

Is there a way to include the function StringPosition["e"] inside the Query in the following: ...
1
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1answer
61 views

A more efficient way to interrogate data inside a Dataset: a generic relational map

I have a Dataset that stores the relationships between people IDs (in columns) and the events they attended (in rows). I want to produce a linear text report of those relationships. How can I do this ...
13
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2answers
325 views

Does anyone know a way to use patterns in Query?

This question is a follow up from my previous question. Query has a nice syntax that allows it to apply functions on association based on specific ...
3
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3answers
395 views

Select specific rows of a dataset

I am struggling with extracting specific rows from a dataset. ...
7
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2answers
245 views

How does Query decide the order in which the functions are applied?

First of all I know that Query is a nice way to organize your functions that are applying at specific levels of an expression. But I don't understand the order in ...
0
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1answer
128 views

Using Semantic Import to do an Excel-like VLookUp using Mathematica

I'm following an example provided in the following Stack Exchange Link but, using a different approach. My data is contained in an Excel workbook called "Input Workbook.xlsx" as shown here: I ...
0
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1answer
112 views

What is the analog of Query in python? [closed]

Is there an analog of Query[] in Python 3.8+?
4
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1answer
76 views

Inconsistency in getting Keys, Values and Query for nested Rules

Querying nested Rule expressions of the form a -> v -> b // FullForm Rule[a,Rule[v,b]] for ...
4
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2answers
113 views

How to pull out the underlying query syntax being used by dataset?

Consider the following dataset. titanic = ExampleData[{"Dataset", "Titanic"}] If I use the lookup syntax of the dataset like following it creates an equivalent <...
8
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2answers
169 views

Query inside Dynamic triggers continuous high CPU load for FE

Here is a (vicious) problem I am able to reproduce with v12 and v11.3 (previous versions not tested) and OSX. This is a minimal example to demonstrate it (even if it seems useless here I do need <...
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0answers
46 views

How do I Select when the key of an association is a multi-word string [closed]

I have imported some survey responses into a Dataset. I now want to select those rows where the response to "participant type" == "Virtual". I discovered that this ...
4
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2answers
80 views

Simple dataset query

Why does taking a Part fail in a Dataset query function when there is an operation in the index argument? ...
2
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1answer
124 views

Replacing values in a dataset

Could someone explain why ...
0
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1answer
154 views

Aggregate function problem

I use a function to do something similar to a SQL sum. I've asked about simplifying it in another post. I'm still using this function and it works well for aggregates like ...
4
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1answer
78 views

Operator form for Histogram of multiple datasets?

I would like to plot a histogram for multiple datasets in a dataset query, but can't quite seem to make it work in operator notation: ...
2
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0answers
35 views

Keyed eigensystem for nested Association

Suppose a matrix is given where both rows and columns are keyed, for example this correlation matrix: ...
2
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1answer
63 views

Handling Missing values flexibly in Query (MissingBehavior problem)

There’s an inconsistency in how Missing values are imputed in Query, with ...
6
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1answer
292 views

How to filter this nested list of Association

For example, I have the following data ...
3
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1answer
129 views

Query from Association of Associations Dataset

I have a rather large dataset comprised of Association of Associations. For better or worse, I've converted this into a Dataset. Here is a simplified version of ...
7
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3answers
272 views

Applying a function by Key pattern, preserving Association order

Any convenient ways to apply a function to Keys that match a pattern in an Association? Method should handle: Mixture of ...
8
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1answer
85 views

Unexpected behavior of PreIncrement when querying associations

For reasons I won't go into here, I became curious about the what would happen should I make a query that applies PreIncrement to one key in a list of associations....
4
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0answers
99 views

How to get parent key in Query on Association/Dataset?

Is there a general and terse method to obtain the parent key of the current "position" in a Query of an Association/...
4
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2answers
32 views

How to Quiet an operator to avoid Query fail

This Query fail, due to divide by zero error message... <|"a" -> 1, "b" -> 0|> // Query[#a/#b &] Missing["Failed"] ...can be prevented by ...
8
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1answer
370 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 ...
3
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1answer
81 views

Dataset type system fail with composite keys and Infinity

In 11.1, a Dataset consisting of an Association with composite keys with an Infinity causes failure in keying-in: ...
9
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2answers
181 views

Getting slices of a nested Association via Query

I'd like to get specific slices from a nested database-like Association through Query. Take for example this toy database of ...
3
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2answers
131 views

Composition with Transpose failure with Dataset

Is the failure of the 2nd Transpose here a known bug? Dataset[{{0, 10}, {2, 11}, {3, 12}}][ Transpose /* Map[MinMax] /* Transpose] // Normal ...
11
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2answers
257 views

Simplifying a reverse Fold for a Query

Is there a simpler way to parametrize this tail-recursive expression to be applied as a Query (for processing a nested ...
9
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2answers
223 views

Slicing an Association with named key span without normalizing?

Is there way to slice an Association with named key span? Span currently doesn't accept named keys: ...
21
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2answers
375 views

Query: adding additional operator changes meaning of preceding operators

Consider the following query: Range[5] // Query[Select[EvenQ] /* Append[1], f] (* {f[2], f[4], 1} *) It selects the even numbers, applies ...
3
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0answers
62 views

Aligning input form of a sequence of Queries

Is there a way to modify the parser, or define options, to align the indentation of a sequence of Queries on a Dataset? Given: ds = <|"a" -> 1, "b" -> <|"c" -> 2|>, "d" -> <|"e" -> 3, "f" ...
12
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0answers
175 views

Unix-like reference to parent and root Association?

Is there a syntax or function to reference parent and root when querying nested Associations similar to Unix' ".." and "/", eg "cd ../../mydir". ? Here's a typical application of the root construct....
2
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1answer
243 views

Query and Dataset Syntax Peculiarities

Question Can someone please explain to me the syntax of Query and why its behavior is so befuddling to me at the moment? I am going to go through a few simple ...
11
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2answers
205 views

Large Dataset query fails if column contains Missing

In version 11.0 (Win 8.1 Pro) a query on a large Dataset for a column that contains Missing fails most unceremoniously. With <...
4
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1answer
168 views

Passing values from a list to Select during a Dataset query

Given a Dataset: ...
6
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1answer
115 views

Mapping (Query) a function at multiple locations in nested data via All, Span

For this data: dt = <|"a"-> <|"x"-> 1|>,"b"-> <|"y"-> 2|>,"c"-> <|"z"->3|>|> It’s awkward when mapping the same ...
11
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2answers
189 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: <...
6
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2answers
135 views

Nothing in a Query

In Mathematica 10, Nothing is defined as to automaticaly disappear when used in a list or in an association, and moreover with the property that it returns ...
17
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1answer
281 views

Aggregation queries on lists of associations in 10.3

Bug introduced in 10.3.0 and fixed in 10.3.1 Bug introduced in 10.3.0 and fixed in 10.4.0 First bug, see first part of the question Second bug, see update part Some aggregation queries applied to ...
21
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1answer
571 views

Struggling to understand Query

The documentation for Query starts with: ...
5
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2answers
461 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 <...
12
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2answers
364 views

Query datasets with “variable” named slots

I want to query a Dataset object, e.g. select some entries using ...
37
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1answer
679 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 ...
2
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0answers
97 views

Reducing quantile & color map queries for use with Associations [closed]

This set of queries perform basic maps to quantile and then color-map. There's got to be a more compact solution. What are some approaches to reduction? Numeric: ...