Questions tagged [query]
The query tag has no usage guidance.
70
questions
4
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views
Apply TimeSeries onto one or more Dataset Columns
I recently responded to a question on Wolfram Community. My solution works, but I believe it could be improved. I'm trying to apply a TimeSeries to one or more ...
- 1,180
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0
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31
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DatabaseFailure when performing a query to PostgreSQL database
I need to retrieve data from a postgresql database. When I create the connection and I try to perform a simple select, it works:
...
- 890
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47
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How to search exact product title with ServiceExecute
I am trying to find the exact product title having phrase "HEPA filter bags" on "amazon.com" but it doesn't return the correct result.
...
- 125
4
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1
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73
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How can default valued be added in a Query?
I'm not understanding the the default values are not used to produced a length of 0 in the following example. What is the right way to add default values during a query?
...
- 12.3k
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65
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Transforming a time-series Dataset
I am trying to perform some analysis on a Dataset instance but my 28K queries involve a Select[#MAC==mac&] over the whole ...
- 376
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22
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How to specify authenticity of SSL for querying APIs?
While ago I was using this command with no issue, now I have an SSL error:
...
- 395
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2
answers
139
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9
votes
1
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181
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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 ...
- 25.3k
4
votes
2
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148
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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 ...
- 420
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1
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161
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56
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3
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97
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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 ...
- 3,720
4
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1
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90
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.
...
- 224k
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31
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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:
...
- 8,075
1
vote
1
answer
71
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 ...
- 163
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2
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341
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 ...
- 8,075
3
votes
3
answers
958
views
Select specific rows of a dataset
I am struggling with extracting specific rows from a dataset.
...
- 177
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2
answers
265
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 ...
- 8,075
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1
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167
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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1
answer
116
views
4
votes
1
answer
90
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 ...
- 14.8k
5
votes
2
answers
124
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 <...
- 8,075
8
votes
2
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179
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 <...
- 7,195
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48
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 ...
- 257
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2
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102
views
Simple dataset query
Why does taking a Part fail in a Dataset query function when there is an operation in the index argument?
...
- 6,091
2
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1
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155
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0
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1
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162
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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 ...
- 3,586
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1
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93
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:
...
- 30.3k
2
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0
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37
views
Keyed eigensystem for nested Association
Suppose a matrix is given where both rows and columns are keyed, for example this correlation matrix:
...
- 14.8k
2
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1
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72
views
Handling Missing values flexibly in Query (MissingBehavior problem)
There’s an inconsistency in how Missing values are imputed in Query, with ...
- 14.8k
6
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1
answer
319
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3
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1
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158
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 ...
- 10.6k
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335
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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 ...
- 14.8k
8
votes
1
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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....
- 106k
4
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0
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112
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/...
- 39.2k
4
votes
2
answers
36
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 ...
- 14.8k
8
votes
1
answer
415
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 ...
- 14.8k
3
votes
1
answer
87
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:
...
- 14.8k
9
votes
2
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190
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 ...
- 8,259
3
votes
2
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145
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
...
- 14.8k
11
votes
2
answers
271
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 ...
- 14.8k
9
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2
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256
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:
...
- 14.8k
21
votes
2
answers
390
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 ...
- 67k
3
votes
0
answers
66
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" ...
- 14.8k
12
votes
0
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177
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....
- 14.8k
2
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1
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318
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 ...
- 5,182
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2
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212
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
<...
- 39.2k
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184
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6
votes
1
answer
117
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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 ...
- 14.8k
11
votes
2
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194
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:
<...
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