npm package discovery and stats viewer.

Discover Tips

  • General search

    [free text search, go nuts!]

  • Package details

    pkg:[package-name]

  • User packages

    @[username]

Sponsor

Optimize Toolset

I’ve always been into building performant and accessible sites, but lately I’ve been taking it extremely seriously. So much so that I’ve been building a tool to help me optimize and monitor the sites that I build to make sure that I’m making an attempt to offer the best experience to those who visit them. If you’re into performant, accessible and SEO friendly sites, you might like it too! You can check it out at Optimize Toolset.

About

Hi, 👋, I’m Ryan Hefner  and I built this site for me, and you! The goal of this site was to provide an easy way for me to check the stats on my npm packages, both for prioritizing issues and updates, and to give me a little kick in the pants to keep up on stuff.

As I was building it, I realized that I was actually using the tool to build the tool, and figured I might as well put this out there and hopefully others will find it to be a fast and useful way to search and browse npm packages as I have.

If you’re interested in other things I’m working on, follow me on Twitter or check out the open source projects I’ve been publishing on GitHub.

I am also working on a Twitter bot for this site to tweet the most popular, newest, random packages from npm. Please follow that account now and it will start sending out packages soon–ish.

Open Software & Tools

This site wouldn’t be possible without the immense generosity and tireless efforts from the people who make contributions to the world and share their work via open source initiatives. Thank you 🙏

© 2024 – Pkg Stats / Ryan Hefner

affinity

v0.0.24

Published

Relational algebra library

Downloads

38

Readme

Affinity

Relational Algebra Library written in JavaScript

Inspired from

Axiom https://github.com/dkubb/axiom

DEE http://www.quicksort.co.uk

##To-do list for 0.1.0##

  • [x] Implement Extend operation
  • [ ] Implement views && updatable views
  • [x] Implement Summarize operation
  • [x] Implement comparison operators (lt, gt, eq, ...)
  • [x] Implement date, string and numeric functions (cos, sin, ...)
  • [ ] More tests
  • [ ] Review documentation

##Installation##

npm install('affinity')
var affinity = require('affinity');

##Documentation##

For Documentation, install the library with npm install affinity and access <install_dir>/docs/index.html in your browser.

Alternatively, the source is extensively documented.

##Relational Algebra##

Relational Algebra and Set Theory are the foundation of SQL implementations. The well known SELECT * WHERE ... are relational algebra operations. Though, Relational Algebra (being a superset of Set Theory) is more strict than many SQL implementations. For example, it does not allow NULL values nor duplicates.

Simply put, a Relation may be viewed as a database table. A table has columns and rows. A Relation has a header and tuples. It is basically the same thing.

###Relation###

A Relation is composed of a Header and a Body.

This is a representation of a relation :

+---------------+---------------------+--------------------+------------------+----------------+
| id : TInteger | firstName : TString | lastName : TString | alive : TBoolean | age : TInteger |
+===============+=====================+====================+==================+================+
| 0             | John                | Doe                | true             | 34             |
+---------------+---------------------+--------------------+------------------+----------------+
| 1             | Mary                | Poppins            | false            | 95             |
+---------------+---------------------+--------------------+------------------+----------------+
| 2             | Mark                | Clinton            | true             | 2              |
+---------------+---------------------+--------------------+------------------+----------------+
| 3             | Hopty               | Duddy              | false            | 10             |
+---------------+---------------------+--------------------+------------------+----------------+

###Set### A Set is a collection of distinct objects (no duplicates)

[1, 2, 3, 4, ...]
['a', 'b', 'c', ...]
[{Object1},{Object2},{Object3},...]

###Header### A Header is a Set of Attributes:

+---------------+---------------------+--------------------+------------------+----------------+
| id : TInteger | firstName : TString | lastName : TString | alive : TBoolean | age : TInteger |
+===============+=====================+====================+==================+================+

###Attribute### An Attribute is a pair (name, type):

+---------------+
| id : TInteger |
+===============+

A Type can be anything (String, Boolean, Object, Vector, Array, even Tuple, Function, Relation, Set, Header...)

###Body### A Body is a Set of Tuples having the same Attributes as the Relation:

+===============+=====================+====================+==================+================+
| 0             | John                | Doe                | true             | 34             |
+---------------+---------------------+--------------------+------------------+----------------+
| 1             | Mary                | Poppins            | false            | 95             |
+---------------+---------------------+--------------------+------------------+----------------+
| 2             | Mark                | Clinton            | true             | 2              |
+---------------+---------------------+--------------------+------------------+----------------+
| 3             | Hopty               | Duddy              | false            | 10             |
+---------------+---------------------+--------------------+------------------+----------------+

###Tuple### A Tuple is a single entry in a Relation. It is an ordered set (attribute1 : value, attribute2 : value...):

+---------------+---------------------+--------------------+------------------+----------------+
| 1             | Mary                | Poppins            | false            | 95             |
+---------------+---------------------+--------------------+------------------+----------------+

Overview


// Declare new relations

var relation = new affinity.Relation([
    {    id: { type: affinity.Integer}},
    {  name: { type: affinity.String }},
    {exists: { type: affinity.Boolean}}
],[
    [1, 'Nicolas',  true ],
    [2, 'Lancelot', false],
    [3, 'Marie',    true ],
    ...
]);

relation.print();

// +--------------+---------------+------------------+
// | id : Integer | name : String | exists : Boolean |
// +==============+===============+==================+
// | 1            | Nicolas       | true             |
// +--------------+---------------+------------------+
// | 2            | Lancelot      | false            |
// +--------------+---------------+------------------+
// | 3            | Marie         | true             |
// +--------------+---------------+------------------+



// Composition
// Like a Join, but removes common attributes

var composed = relation.compose(relation2);



// Difference
// Get tuples in A that are not in B

var difference = relation.difference(relation2);



// Extension
// Adds calculated columns to a relation

var extended = relation.extend([{ newCol : id.plus(name.length())}]);

extended.print();

// +--------------+---------------+------------------+------------------+
// | id : Integer | name : String | exists : Boolean | newCol : Integer |
// +==============+===============+==================+==================+
// | 1            | Nicolas       | true             | 8                |
// +--------------+---------------+------------------+------------------+
// | 2            | Lancelot      | false            | 10               |
// +--------------+---------------+------------------+------------------+
// | 3            | Marie         | true             | 8                |
// +--------------+---------------+------------------+------------------+



// Group
// Groups columns into a RVA (Relation-Valued-Attribute)

var grouped = relation.group('persons', ['id', 'exists']);

grouped.print();

// +---------------+------------------------------------+
// | name : String | persons : Relation                 |
// +===============+====================================+
// | Nicolas       | +--------------+------------------+|
// |               | | id : Integer | exists : Boolean ||
// |               | +==============+==================+|
// |               | | 1            | true             ||
// |               | +--------------+------------------+|
// +---------------+------------------------------------+
// | Lancelot      | +--------------+------------------+|
// |               | | id : Integer | exists : Boolean ||
// |               | +==============+==================+|
// |               | | 2            | false            ||
// |               | +--------------+------------------+|
// +---------------+------------------------------------+
// | Marie         | +--------------+------------------+|
// |               | | id : Integer | exists : Boolean ||
// |               | +==============+==================+|
// |               | | 3            | true             ||
// |               | +--------------+------------------+|
// +---------------+------------------------------------+

// Ungroup
// Ungroups RVAs

var ungrouped = grouped.ungroup(['persons']);



// Intersection
// Tuples in B that are also in A

var intersected = relation.intersect(otherRelation);



// Joined
// Combinations of tuples in A and B that have the same values for their common attributes

var joined = relation.join(otherRelation);



// Product
// All possible combinations of tuples in A and in B

var product = relation.product(otherRelation);



// Projection
// Selects columns from a relation

var projected = relation.project(['name', 'exists']);



// Rename
// Renames attributes of a relation

var renamed = relation.rename({ name : 'newName', exists : 'newExists' });



// Restriction
// Selects tuple that match a given predicate

var restricted = relation.restrict(
    name.substr(0,1).lowercase().eq('l').or(name.substr(0,1).lowercase().eq('m'))
);

// +--------------+---------------+------------------+
// | id : Integer | name : String | exists : Boolean |
// +==============+===============+==================+
// | 2            | Lancelot      | false            |
// +--------------+---------------+------------------+
// | 3            | Marie         | true             |
// +--------------+---------------+------------------+



// SemiDifference
// Inverse of SemiJoin : Finds tuples in A that do not have a counterpart in B

var semidifference = relation.semiDifference(otherRelation);



// SemiJoin
// Finds tuples in A that have a counterpart in B. Like a Join, but only returns attributes from A

var semijoined = relation.semiJoin(otherRelation);



// Wrap
// Wraps given attributes into a TVA (tuple-valued-attribute);

var wrapped = relation.wrap('person', ['id', 'exists']);

wrapped.print();

// +--------------+--------------------------------------------+
// | id : Integer | person : Tuple                             |
// +==============+============================================+
// | 1            | Tuple(name : 'Nicolas', exists : 'true')   |
// +--------------+--------------------------------------------+
// | 2            | Tuple(name : 'Lancelot', exists : 'false') |
// +--------------+--------------------------------------------+
// | 3            | Tuple(name : 'Marie', exists : 'true')     |
// +--------------+--------------------------------------------+



// Unwrap
// Inverse of Wrap

var unwrapped = relation.unwrap(['person']);

Predicates

For the Restriction and Extension operations, you must pass a predicate that can be composed with the following :

e.g.:


relation.restrict(age.gt(10));  // age > 10

relation.restrict(age.gt(10).or(age.st(50))); // age > 10 || age < 50

relation.extend([
    { lived : died.minus(born) }
])

| Function | Shortcut | Returns | |:---------------------|:--------------|:----------------| |Connectives ||| |And |and |Boolean | |Or |or |Boolean | |Not |not |Boolean | |Tuple | |TupleValue |value |* | |Comparison ||| |Equal |eq |Boolean | |Greater Than |gt |Boolean | |Greater Than or Equal |gte |Boolean | |Smaller Than |st |Boolean | |Smaller Than or Equal |ste |Boolean | |Numeric Functions ||| |Absolute |abs |Numeric | |Ceil |ceil |Numeric | |Cosine |cos |Numeric | |Division |div |Numeric | |Exponential |exp |Numeric | |Minus |minus |Numeric | |Modulo |mod |Numeric | |Multiplication |times |Numeric | |Plus |plus |Numeric | |Power |pow |Numeric | |Roof |roof |Numeric | |Round |round |Numeric | |Sine |sin |Numeric | |Square Root |sqrt |Numeric | |String Functions ||| |Length |length |Integer | |Lowercase |lowercase |String | |Matching |matching |Boolean | |Substring |substr |String | |Uppercase |uppercase |String | |Date Functions ||| |Day of Month |dayOfMonth |Integer | |Day of Week |dayOfWeek |Integer | |Day of Year |dayOfYear |Integer | |Week of Year |weekOfYear |Integer | |Year |year |Integer | |Month |month |Integer | |Hours |hours |Integer | |Minutes |minutes |Integer | |Seconds |seconds |Integer | |Milliseconds |milliseconds |Integer | |Timestamp |ts |Integer |