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## subarrays ##
type SubArray{T,N,A<:AbstractArray,I<:(RangeIndex...,)} <: AbstractArray{T,N}
parent::A
indexes::I
dims::Dims
strides::Array{Int,1} # for accessing parent with linear indexes
first_index::Int
#linear indexing constructor (scalar)
if N == 0 && length(I) == 1 && A <: Array
function SubArray(p::A, i::(Int,))
new(p, i, (), Int[], i[1])
end
#linear indexing constructor (ranges)
elseif N == 1 && length(I) == 1 && A <: Array
function SubArray(p::A, i::(Range1{Int},))
new(p, i, (length(i[1]),), [1], first(i[1]))
end
function SubArray(p::A, i::(Range{Int},))
new(p, i, (length(i[1]),), [step(i[1])], first(i[1]))
end
else
function SubArray(p::A, i::I)
newdims = Array(Int, 0)
newstrides = Array(Int, 0)
newfirst = 1
pstride = 1
for j = 1:length(i)
if isa(i[j], Int)
newfirst += (i[j]-1)*pstride
else
push(newdims, length(i[j]))
#may want to return error if step(i[j]) <= 0
push(newstrides, isa(i[j],Range1) ? pstride :
pstride * step(i[j]))
newfirst += (first(i[j])-1)*pstride
end
pstride *= size(p,j)
end
new(p, i, tuple(newdims...), newstrides, newfirst)
end
end
end
#linear indexing sub (may want to rename as slice)
function sub{T,N}(A::Array{T,N}, i::(RangeIndex,))
SubArray{T,(isa(i[1], Int) ? 0 : 1),typeof(A),typeof(i)}(A, i)
end
function sub{T,N}(A::AbstractArray{T,N}, i::NTuple{N,RangeIndex})
L = length(i)
while L > 0 && isa(i[L], Int); L-=1; end
i0 = map(j -> isa(j, Int) ? (j:j) : j, i[1:L])
i = ntuple(length(i), k->(k<=L ? i0[k] : i[k]))
SubArray{T,L,typeof(A),typeof(i)}(A, i)
end
sub(A::AbstractArray, i::RangeIndex...) = sub(A, i)
function sub(A::SubArray, i::RangeIndex...)
L = length(i)
while L > 0 && isa(i[L], Int); L-=1; end
j = 1
newindexes = Array(RangeIndex,length(A.indexes))
for k = 1:length(A.indexes)
if isa(A.indexes[k], Int)
newindexes[k] = A.indexes[k]
else
newindexes[k] = A.indexes[k][(isa(i[j],Int) && j<=L) ? (i[j]:i[j]) : i[j]]
j += 1
end
end
sub(A.parent, tuple(newindexes...))
end
function slice{T,N}(A::AbstractArray{T,N}, i::NTuple{N,RangeIndex})
n = 0
for j = i; if !isa(j, Int); n += 1; end; end
SubArray{T,n,typeof(A),typeof(i)}(A, i)
end
slice(A::AbstractArray, i::RangeIndex...) = slice(A, i)
function slice(A::SubArray, i::RangeIndex...)
j = 1
newindexes = Array(RangeIndex,length(A.indexes))
for k = 1:length(A.indexes)
if isa(A.indexes[k], Int)
newindexes[k] = A.indexes[k]
else
newindexes[k] = A.indexes[k][i[j]]
j += 1
end
end
slice(A.parent, tuple(newindexes...))
end
### rename the old slice function ###
##squeeze all dimensions of length 1
#slice{T,N}(a::AbstractArray{T,N}) = sub(a, map(i-> i == 1 ? 1 : (1:i), size(a)))
#slice{T,N}(s::SubArray{T,N}) =
# sub(s.parent, map(i->!isa(i, Int) && length(i)==1 ?i[1] : i, s.indexes))
#
##slice dimensions listed, error if any have length > 1
##silently ignores dimensions that are greater than N
#function slice{T,N}(a::AbstractArray{T,N}, sdims::Integer...)
# newdims = ()
# for i = 1:N
# next = 1:size(a, i)
# for j in sdims
# if i == j
# if size(a, i) != 1
# error("slice: dimension ", i, " has length greater than 1")
# end
# next = 1
# break
# end
# end
# newdims = tuple(newdims..., next)
# end
# sub(a, newdims)
#end
#function slice{T,N}(s::SubArray{T,N}, sdims::Integer...)
# newdims = ()
# for i = 1:length(s.indexes)
# next = s.indexes[i]
# for j in sdims
# if i == j
# if length(next) != 1
# error("slice: dimension ", i," has length greater than 1")
# end
# next = isa(next, Int) ? next : first(next)
# break
# end
# end
# newdims = tuple(newdims..., next)
# end
# sub(s.parent, newdims)
#end
### end commented code ###
size(s::SubArray) = s.dims
ndims{T,N}(s::SubArray{T,N}) = N
copy(s::SubArray) = copy_to(similar(s.parent, size(s)), s)
similar(s::SubArray, T, dims::Dims) = similar(s.parent, T, dims)
ref{T}(s::SubArray{T,0,AbstractArray{T,0}}) = s.parent[]
ref{T}(s::SubArray{T,0}) = s.parent[s.first_index]
ref{T}(s::SubArray{T,1}, i::Integer) = s.parent[s.first_index + (i-1)*s.strides[1]]
ref{T}(s::SubArray{T,2}, i::Integer, j::Integer) =
s.parent[s.first_index + (i-1)*s.strides[1] + (j-1)*s.strides[2]]
ref(s::SubArray, i::Integer) = s[ind2sub(size(s), i)...]
function ref{T}(s::SubArray{T,2}, ind::Integer)
ld = size(s,1)
i = rem(ind-1,ld)+1
j = div(ind-1,ld)+1
s.parent[s.first_index + (i-1)*s.strides[1] + (j-1)*s.strides[2]]
end
function ref(s::SubArray, is::Integer...)
index = s.first_index
for i = 1:length(is)
index += (is[i]-1)*s.strides[i]
end
s.parent[index]
end
ref{T}(s::SubArray{T,1}, I::Range1{Int}) =
ref(s.parent, (s.first_index+(first(I)-1)*s.strides[1]):s.strides[1]:(s.first_index+(last(I)-1)*s.strides[1]))
ref{T}(s::SubArray{T,1}, I::Range{Int}) =
ref(s.parent, (s.first_index+(first(I)-1)*s.strides[1]):(s.strides[1]*step(I)):(s.first_index+(last(I)-1)*s.strides[1]))
function ref{T,S<:Integer}(s::SubArray{T,1}, I::AbstractVector{S})
t = Array(Int, length(I))
for i = 1:length(I)
t[i] = s.first_index + (I[i]-1)*s.strides[1]
end
ref(s.parent, t)
end
function ref(s::SubArray, I::Indices...)
I = indices(I)
n = ndims(s.parent)
newindexes = Array(Indices, n)
for i = 1:n
t = s.indexes[i]
#TODO: don't generate the dense vector indexes if they can be ranges
newindexes[i] = isa(t, Int) ? t : t[I[i]]
end
reshape(ref(s.parent, newindexes...), ref_shape(I...))
end
assign(s::SubArray, v, i::Integer) = assign(s, v, ind2sub(size(s), i)...)
function assign{T}(s::SubArray{T,2}, v, ind::Integer)
ld = size(s,1)
i = rem(ind-1,ld)+1
j = div(ind-1,ld)+1
s.parent[s.first_index + (i-1)*s.strides[1] + (j-1)*s.strides[2]] = v
return s
end
function assign(s::SubArray, v, is::Integer...)
index = s.first_index
for i = 1:length(is)
index += (is[i]-1)*s.strides[i]
end
s.parent[index] = v
return s
end
assign{T}(s::SubArray{T,0,AbstractArray{T,0}},v) = assign(s.parent, v)
assign{T}(s::SubArray{T,0}, v) = assign(s.parent, v, s.first_index)
assign{T}(s::SubArray{T,1}, v, i::Integer) =
assign(s.parent, v, s.first_index + (i-1)*s.strides[1])
assign{T}(s::SubArray{T,2}, v, i::Integer, j::Integer) =
assign(s.parent, v, s.first_index +(i-1)*s.strides[1]+(j-1)*s.strides[2])
assign{T}(s::SubArray{T,1}, v, I::Range1{Int}) =
assign(s.parent, v, (s.first_index+(first(I)-1)*s.strides[1]):s.strides[1]:(s.first_index+(last(I)-1)*s.strides[1]))
assign{T}(s::SubArray{T,1}, v, I::Range{Int}) =
assign(s.parent, v, (s.first_index+(first(I)-1)*s.strides[1]):(s.strides[1]*step(I)):(s.first_index+(last(I)-1)*s.strides[1]))
function assign{T,S<:Integer}(s::SubArray{T,1}, v, I::AbstractVector{S})
t = Array(Int, length(I))
for i = 1:length(I)
t[i] = s.first_index + (I[i]-1)*s.strides[1]
end
assign(s.parent, v, t)
end
function assign(s::SubArray, v, I::Indices...)
I = indices(I)
j = 1 #the jth dimension in subarray
n = ndims(s.parent)
newindexes = cell(n)
for i = 1:n
t = s.indexes[i]
#TODO: don't generate the dense vector indexes if they can be ranges
newindexes[i] = isa(t, Int) ? t : t[I[j]]
j += 1
end
assign(s.parent, v, newindexes...)
end
function stride(s::SubArray, i::Integer)
k = stride(s.parent, i)
j = s.indexes[i]
if isa(j,Range)
return k*step(j)
end
return k
end
convert{T}(::Type{Ptr{T}}, x::SubArray{T}) =
pointer(x.parent) + (x.first_index-1)*sizeof(T)
pointer(s::SubArray, i::Int) = pointer(s, ind2sub(size(s), i))
function pointer(s::SubArray, is::(Int...))
index = s.first_index
for n = 1:length(is)
index += (is[n]-1)*s.strides[n]
end
return pointer(s.parent, index)
end
summary(s::SubArray) =
strcat(dims2string(size(s)), " SubArray of ", summary(s.parent))
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