Questions tagged [query]
The query tag has no usage guidance.
64
questions
4
votes
2answers
112 views
8
votes
1answer
112 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
votes
2answers
92 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
votes
1answer
148 views
2
votes
0answers
54 views
2
votes
0answers
59 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
votes
1answer
65 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.
...
0
votes
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
vote
1answer
62 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
votes
2answers
328 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
votes
3answers
496 views
7
votes
2answers
251 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
votes
1answer
136 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
votes
1answer
112 views
4
votes
1answer
78 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
votes
2answers
114 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
votes
2answers
172 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 <...
1
vote
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
votes
2answers
83 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
votes
1answer
130 views
0
votes
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
votes
1answer
80 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
votes
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
votes
1answer
64 views
Handling Missing values flexibly in Query (MissingBehavior problem)
There’s an inconsistency in how Missing values are imputed in Query, with ...
6
votes
1answer
295 views
3
votes
1answer
134 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
votes
3answers
279 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
votes
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
votes
0answers
100 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
votes
2answers
33 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
votes
1answer
377 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
votes
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
votes
2answers
182 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
votes
2answers
133 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
votes
2answers
262 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
votes
2answers
240 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
votes
2answers
378 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
votes
0answers
63 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
votes
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
votes
1answer
252 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
votes
2answers
206 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
votes
1answer
170 views
6
votes
1answer
116 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
votes
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
votes
2answers
137 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
votes
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 ...
23
votes
1answer
588 views
5
votes
2answers
485 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
votes
2answers
368 views
Query datasets with “variable” named slots
I want to query a Dataset object, e.g. select some entries using
...
37
votes
1answer
690 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 ...
