Sets

Description

This crate defines Struct: Set, wrapping up five kinds of sets: Empty, Unordered, Ordered, Indexed and Ranked, and common methods acting upon them. It adds organisation and type safety to some primitive methods imported from crate indxvec.

The main capabilities of Sets include the usual set operations, plus efficient sorting, ranking, searching, etc. The aim is to avoid moving data as much as possible. This is done by manipulating indices instead. These methods work on any generic vectors (or slices) of primitive end types <T>. Also, on any arbitrarily complex user end type, as long as the required traits PartialOrd and Copy, are implemented for it by the user.

Usage

Insert into Cargo.toml file, under [dependencies]: sets = "^1"
The following 'use' declaration in source files makes available everything:

use sets::{Set,MutSetOps};

Set<T>

/// The struct type for sets
#[derive(Default)]
pub struct Set<T> {
    /// type of the set
    pub stype: SType,
    /// order: ascending (true), descending (false)
    pub ascending: bool,
    /// data Vec
    pub data: Vec<T>,
    /// index Vec
    pub index: Vec<usize>
}

Clone and Display traits are implemented for Set and SType.
Default is derived, thus Default::default() generates a copy of an empty set.

SType specifies one of the five kinds of sets. It is dealt with by 'enumeration generics'.

/// The five types of sets
#[derive(Default,Clone,Copy)]
pub enum SType {
    /// empty set
    #[default]
    Empty,
    /// unordered set
    Unordered,
    /// ordered set
    Ordered,
    /// indexed set
    Indexed,
    /// ranked set
    Ranked
}

Associated Initialisers

Initialisers are associated with the struct Set, hence to invoke them, the :: syntax is necessary, e.g. Set::new(..)

    /// all in one Initialiser creates a new Set
    /// of any self_type SType, from slice d, in asc order 
    pub fn new(set_type: SType, d: &[T], asc:bool) -> Self

There are also explicitly named convenience functions for all STypes: new_empty, new_unordered, new_ordered, new_indexed, new_ranked. All the ordered types (i.e. ordered, indexed, ranked) take a bool argument specifying ascending or descending order.

Converters

    /// General converter - 
    /// converts s to a Set of the same type and order as self 
    /// (self only serves as a template).
    pub fn to_same(&self, s:&Self) -> Self 

Again, we have explicitly named converters: to_unordered, to_ordered, to_indexed, to_ranked.

   let v = vec![1.,14.,2.,13.,3.,12.];
   let setv = Set::new_unordered(&v);  
   println!("{}",setv); // Display setv 
   // ordered, ascending  
   println!("{}",setv.to_ordered(true)); 
   // indexed, descending
   println!("{}",setv.to_indexed(false)); 

It is highly recommended to read and run tests/tests.rs for more examples of usage. Use a single thread to run them. It may be a bit slower but it will write the results in the right order:

cargo test --release -- --test-threads=1 --nocapture --color always

Set Functions

Some of the general methods are more efficient for the ordered and indexed sets, rather than for the unordered sets. For example, member and search will automatically use the binary search. Union is like the classical merge with duplications across the sets removed. To remove repetitions within a set, use nonrepeat.

The STypes of the two operands of union, intersection and difference can be different. However, they are required to have the same end-type <T>. This is, perhaps, a useful type discipline.

Trait MutSetOps

Here 'm' in the methods' names stands for 'mutable'. They overwrite the mutable set to which they are applied with the result. Thus they are not functional but in the context of handling large vectors, they are often simpler and more efficient. At the price of destroying the previous contents of self, of course.

/// Mutable methods for &mut Set<T>
pub trait MutSetOps<T> {
    /// Makes a Set unordered
    fn munordered(&mut self);
    /// Makes a Set ordered
    fn mordered(&mut self, asc:bool) where f64:From<T>;
    /// Makes any Set indexed
    fn mindexed(&mut self,asc:bool) where f64:From<T>;
    /// Converts any Set type to ranked
    fn mranked(&mut self,asc:bool);
    /// General converter: s -> Set of the same type and order as self
    fn msame(&mut self, s:&mut Self) where f64:From<T>; 
    /// Deletes the first item from self
    fn mdelete(&mut self, item:T) -> bool;
    /// Deletes all occurrences of a matching item from self, returns their count
    fn mdeleteall(&mut self, item:T) -> usize;
    /// Inserts an item of the same end-type to self
    fn minsert(&mut self, item:T);
    /// reverses the vector of explicit sets and index of indexed sets
    fn mreverse(&mut self);
    /// Deletes any repetitions
    fn mnonrepeat(&mut self); 
    /// Union of two sets of the same type
    fn munion(&mut self, s: &Self);
    /// Intersection of two sets of the same type
    fn mintersection(&mut self, s: &Self);
    /// Removing s from self (i.e. self-s)
    fn mdifference(&mut self, s: &Self);
}

Release Notes (Latest First)

Version 1.1.3 - Updated dependency indxvec 1.4.2.

Version 1.1.2 - Updated to indxvec 1.3.3. Pruned and simplified some code. Added deleteall to trait MutSetOps.

Version 1.1.1 - Eliminating unnecessary cloning. Updating to the latest dependency on indxvec 1.2.8.

Version 1.1.0 - Joined all four types of sets into one Struct Set. Simplified and generalised code by using enum generics.

Version 1.0.6 - Added mutable methods minsert and mdelete to MutSetOps, that insert or remove one specific item to/from any of the sets. Added tests of them to tests/tests.rs. Updated indxvec dependency to its version 1.2.4 or greater.

Version 1.0.5 - Documentation improvements.

Version 1.0.4 - nonrepeat now always returns an OrderedSet. Clarified settest.

Version 1.0.3 - updated to be compatible with indxvec version 1.2.1. Improved munion.

Version 1.0.2 - some changes to printing to reflect changes to indxvec.

Version 1.0.1 - some tidying up of code, no changes of functionality.

Version 1.0.0 - stable version with some minor improvements to README.md (this document). Updated to indxvec = "^1" and Rust edition 2021.