Collections and Data Structures

Iteration

Sequential iteration is implemented by the methods start(), done(), and next(). The general for loop:

for i = I   # or  "for i in I"
    # body
end

is translated into:

state = start(I)
while !done(I, state)
    (i, state) = next(I, state)
    # body
end

The state object may be anything, and should be chosen appropriately for each iterable type. See the manual section on the iteration interface for more details about defining a custom iterable type.

```@docs Base.start Base.done Base.next Base.iteratorsize Base.iteratoreltype


Fully implemented by:

  * `Range`
  * `UnitRange`
  * `Tuple`
  * `Number`
  * [`AbstractArray`](@ref)
  * [`IntSet`](@ref)
  * [`ObjectIdDict`](@ref)
  * [`Dict`](@ref)
  * [`WeakKeyDict`](@ref)
  * `EachLine`
  * `AbstractString`
  * [`Set`](@ref)

## General Collections

```@docs
Base.isempty
Base.empty!
Base.length(::Any)

Fully implemented by:

Iterable Collections

```@docs Base.in Base.eltype Base.indexin Base.findin Base.unique Base.unique! Base.allunique Base.reduce(::Any, ::Any, ::Any) Base.reduce(::Any, ::Any) Base.foldl(::Any, ::Any, ::Any) Base.foldl(::Any, ::Any) Base.foldr(::Any, ::Any, ::Any) Base.foldr(::Any, ::Any) Base.maximum(::Any) Base.maximum(::Any, ::Any) Base.maximum! Base.minimum(::Any) Base.minimum(::Any, ::Any) Base.minimum! Base.extrema(::Any) Base.extrema(::AbstractArray, ::Any) Base.indmax Base.indmin Base.findmax(::Any) Base.findmax(::AbstractArray, ::Any) Base.findmin(::Any) Base.findmin(::AbstractArray, ::Any) Base.findmax! Base.findmin! Base.sum Base.sum! Base.prod Base.prod! Base.any(::Any) Base.any(::AbstractArray, ::Any) Base.any! Base.all(::Any) Base.all(::AbstractArray, ::Any) Base.all! Base.count Base.any(::Any, ::Any) Base.all(::Any, ::Any) Base.foreach Base.map Base.map! Base.mapreduce(::Any, ::Any, ::Any, ::Any) Base.mapreduce(::Any, ::Any, ::Any) Base.mapfoldl(::Any, ::Any, ::Any, ::Any) Base.mapfoldl(::Any, ::Any, ::Any) Base.mapfoldr(::Any, ::Any, ::Any, ::Any) Base.mapfoldr(::Any, ::Any, ::Any) Base.first Base.last Base.step Base.collect(::Any) Base.collect(::Type, ::Any) Base.issubset(::Any, ::Any) Base.filter Base.filter!


## Indexable Collections

```@docs
Base.getindex(::Any, ::Any...)
Base.setindex!(::Any, ::Any, ::Any...)
Base.endof

Fully implemented by:

Partially implemented by:

Associative Collections

Dict is the standard associative collection. Its implementation uses hash() as the hashing function for the key, and isequal() to determine equality. Define these two functions for custom types to override how they are stored in a hash table.

ObjectIdDict is a special hash table where the keys are always object identities.

WeakKeyDict is a hash table implementation where the keys are weak references to objects, and thus may be garbage collected even when referenced in a hash table.

Dicts can be created by passing pair objects constructed with =>() to a Dict constructor: Dict("A"=>1, "B"=>2). This call will attempt to infer type information from the keys and values (i.e. this example creates a Dict{String, Int64}). To explicitly specify types use the syntax Dict{KeyType,ValueType}(...). For example, Dict{String,Int32}("A"=>1, "B"=>2).

Associative collections may also be created with generators. For example, Dict(i => f(i) for i = 1:10).

Given a dictionary D, the syntax D[x] returns the value of key x (if it exists) or throws an error, and D[x] = y stores the key-value pair x => y in D (replacing any existing value for the key x). Multiple arguments to D[...] are converted to tuples; for example, the syntax D[x,y] is equivalent to D[(x,y)], i.e. it refers to the value keyed by the tuple (x,y).

```@docs Base.Dict Base.ObjectIdDict Base.WeakKeyDict Base.haskey Base.get(::Any, ::Any, ::Any) Base.get Base.get!(::Any, ::Any, ::Any) Base.get!(::Function, ::Any, ::Any) Base.getkey Base.delete! Base.pop!(::Any, ::Any, ::Any) Base.keys Base.values Base.merge Base.merge!(::Associative, ::Associative...) Base.merge!(::Function, ::Associative, ::Associative...) Base.sizehint! Base.keytype Base.valtype


Fully implemented by:

  * [`ObjectIdDict`](@ref)
  * [`Dict`](@ref)
  * [`WeakKeyDict`](@ref)

Partially implemented by:

  * [`IntSet`](@ref)
  * [`Set`](@ref)
  * [`EnvHash`](@ref Base.EnvHash)
  * [`Array`](@ref)
  * [`BitArray`](@ref)

## Set-Like Collections

```@docs
Base.Set
Base.IntSet
Base.union
Base.union!
Base.intersect
Base.setdiff
Base.setdiff!
Base.symdiff
Base.symdiff!(::IntSet, ::Integer)
Base.symdiff!(::IntSet, ::Any)
Base.symdiff!(::IntSet, ::IntSet)
Base.intersect!
Base.issubset

Fully implemented by:

Partially implemented by:

Dequeues

@docs Base.push! Base.pop!(::Any) Base.unshift! Base.shift! Base.insert! Base.deleteat! Base.splice! Base.resize! Base.append! Base.prepend!

Fully implemented by:

  • Vector (a.k.a. 1-dimensional Array)
  • BitVector (a.k.a. 1-dimensional BitArray)