in-place load! for multi-file datasets

src/CatArrays.jl

@@ -74,28 +74,42 @@ function CatArray(dim::Int,arrays...)
         sz)
 end
 
-
-function Base.getindex(CA::CatArray{T,N},idx...) where {T,N}
-    checkbounds(CA,idx...)
-
-    sz = _shape_after_slice(size(CA),idx...)
+function load!(CA::CatArray{T,N},B,idx...) where {T,N}
     idx_global_local = index_global_local(CA,idx)
-    B = Array{T,length(sz)}(undef,sz...)
 
     for (array,(idx_global,idx_local)) in zip(CA.arrays,idx_global_local)
         if valid_local_idx(idx_local...)
             # get subset from subarray
-            subset = array[idx_local...]
-            B[idx_global...] = subset
+            subset = @view array[idx_local...]
+            B[idx_global...] .= subset
         end
     end
 
-    if sz == ()
-        # scalar
-        return B[]
-    else
-        return B
+    return B
+end
+
+function Base.getindex(CA::CatArray{T,N},idx::Integer...) where {T,N}
+    checkbounds(CA,idx...)
+    idx_global_local = index_global_local(CA,idx)
+    B = Ref{T}()
+
+    for (array,(idx_global,idx_local)) in zip(CA.arrays,idx_global_local)
+        if valid_local_idx(idx_local...)
+            B[] = array[idx_local...]
+        end
     end
+
+    return B[]
+end
+
+function Base.getindex(CA::CatArray{T,N},idx...) where {T,N}
+    checkbounds(CA,idx...)
+
+    sz = _shape_after_slice(size(CA),idx...)
+    B = Array{T,length(sz)}(undef,sz...)
+
+    load!(CA,B,idx...)
+    return B
 end
 
 Base.size(CA::CatArray) = CA.sz

src/multifile.jl

@@ -160,6 +160,9 @@ end
 Base.getindex(v::MFVariable,indexes::Union{Int,Colon,AbstractRange{<:Integer}}...) = getindex(v.var,indexes...)
 Base.setindex!(v::MFVariable,data,indexes::Union{Int,Colon,AbstractRange{<:Integer}}...) = setindex!(v.var,data,indexes...)
 
+
+load!(v::MFVariable,buffer,indexes...) = CatArrays.load!(v.var,buffer,indexes...)
+
 Base.size(v::MFVariable) = size(v.var)
 Base.size(v::MFCFVariable) = size(v.var)
 dimnames(v::MFVariable) = v.dimnames

test/test_multifile.jl

@@ -132,10 +132,11 @@ fnames = example_file.(TDS,1:3,A)
 
 varname = "var"
 
+#deferopen = false
 for deferopen in (false,true)
     local mfds, data
     local lon
-    local buf, ds_merged, fname_merged, var
+    local buf, ds_merged, fname_merged, var, ncv
 
     mfds = TDS(fnames, deferopen = deferopen);
 
@@ -184,14 +185,13 @@ for deferopen in (false,true)
     @test mfds["lon"][1:1] == ds_merged["lon"][:]
     close(ds_merged)
 
-#=
-    # save subset of aggregated file (deprecated)
-    fname_merged = tempname()
-    write(fname_merged,mfds,idimensions = Dict("lon" => 1:1))
-    ds_merged = TDS(fname_merged)
-    @test mfds["lon"][1:1] == ds_merged["lon"][:]
-    close(ds_merged)
-=#
+
+    # in-place load
+    ncv = mfds[varname].var
+    buffer = zeros(eltype(ncv),size(ncv))
+    load!(ncv,buffer,:,:,:)
+    @test buffer == C
+
     # show
     buf = IOBuffer()
     show(buf,mfds)