Export open_mfdataset (#470)

* upgrade and export open_mfdataset

* use newest YAXArrayBase

* Fix unrelated test

* add dependabot

* Apply suggestions from code review

* fix locally

---------

Co-authored-by: Lazaro Alonso <lazarus.alon@gmail.com>

.github/dependabot.yml

@@ -0,0 +1,7 @@
+# https://docs.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/" # Location of package manifests
+    schedule:
+      interval: "weekly"

Project.toml

@@ -54,5 +54,5 @@ Statistics = "1"
 StatsBase = "0.32, 0.33, 0.34"
 Tables = "0.2, 1.0"
 WeightedOnlineStats = "0.3, 0.4, 0.5, 0.6"
-YAXArrayBase = "0.6, 0.7"
+YAXArrayBase = "0.7.5"
 julia = "1.9"

src/DatasetAPI/Datasets.jl

@@ -13,7 +13,7 @@ using DiskArrays: DiskArrays, GridChunks
 using Glob: glob
 using DimensionalData: DimensionalData as DD
 
-export Dataset, Cube, open_dataset, to_dataset, savecube, savedataset
+export Dataset, Cube, open_dataset, to_dataset, savecube, savedataset, open_mfdataset
 
 """
     Dataset object which stores an `OrderedDict` of YAXArrays with Symbol keys.
@@ -253,7 +253,7 @@ function collectdims(g)
     varnames = get_varnames(g)
     foreach(varnames) do k
         d = get_var_dims(g, k)
-        v = get_var_handle(g, k)
+        v = get_var_handle(g, k, persist=false)
         for (len, dname) in zip(size(v), d)
             if !occursin("bnd", dname) && !occursin("bounds", dname)
                 datts = if dname in varnames
@@ -277,7 +277,7 @@ function toaxis(dimname, g, offs, len)
     if !haskey(g, dimname)
         return DD.rebuild(DD.name2dim(axname), 1:len)
     end
-    ar = get_var_handle(g, dimname)
+    ar = get_var_handle(g, dimname, persist=false)
     aratts = get_var_attrs(g, dimname)
     if match(r"^(days)|(hours)|(seconds)|(months) since",lowercase(get(aratts,"units",""))) !== nothing
         tsteps = try
@@ -337,6 +337,63 @@ open_mfdataset(g::AbstractString; kwargs...) = open_mfdataset(_glob(g); kwargs..
 open_mfdataset(g::Vector{<:AbstractString}; kwargs...) =
 merge_datasets(map(i -> open_dataset(i; kwargs...), g))
 
+function merge_new_axis(alldatasets, firstcube,var,mergedim)
+    newdim = DD.rebuild(mergedim,1:length(alldatasets))
+    alldiskarrays = map(ds->ds.cubes[var].data,alldatasets).data
+    newda = diskstack(alldiskarrays)
+    newdims = (DD.dim(firstcube)...,newdim)
+    YAXArray(newdims,newda,deepcopy(firstcube.properties))
+end
+function merge_existing_axis(alldatasets,firstcube,var,mergedim)
+    allaxvals = map(ds->DD.dims(ds.cubes[var],mergedim).val,alldatasets)
+    newaxvals = reduce(vcat,allaxvals)
+    newdim = DD.rebuild(mergedim,newaxvals)
+    alldiskarrays = map(ds->ds.cubes[var].data,alldatasets)
+    istack = DD.dimnum(firstcube,mergedim)
+    newshape = ntuple(i->i!=istack ? 1 : length(alldiskarrays),ndims(firstcube))
+    newda = DiskArrays.ConcatDiskArray(reshape(alldiskarrays,newshape))
+    newdims = Base.setindex(firstcube.axes,newdim,istack)
+    YAXArray(newdims,newda,deepcopy(firstcube.properties))
+end
+
+"""
+    open_mfdataset(files::DD.DimVector{<:AbstractString}; kwargs...)
+
+Opens and concatenates a list of dataset paths along the dimension specified in `files`. 
+This method can be used when the generic glob-based version of open_mfdataset fails
+or is too slow. 
+For example, to concatenate a list of annual NetCDF files along the `Ti` dimension, 
+one can use:
+
+````julia
+files = ["1990.nc","1991.nc","1992.nc"]
+open_mfdataset(DD.DimArray(files,DD.Ti()))
+````
+
+alternatively, if the dimension to concatenate along does not exist yet, the 
+dimension provided in the input arg is used:
+
+````julia
+files = ["a.nc","b.nc","c.nc"]
+open_mfdataset(DD.DimArray(files,DD.Dim{:NewDim}(["a","b","c"])))
+````
+"""
+function open_mfdataset(vec::DD.DimVector{<:AbstractString};kwargs...)
+    alldatasets = open_dataset.(vec;kwargs...);
+    fi = first(alldatasets)
+    mergedim = DD.dims(alldatasets) |> only
+    ars = map(collect(keys(fi.cubes))) do var
+        cfi = fi.cubes[var]
+        mergedar = if DD.dims(cfi,mergedim) !== nothing
+            merge_existing_axis(alldatasets,cfi,var,mergedim) 
+        else
+            merge_new_axis(alldatasets,cfi,var,mergedim)
+        end
+        var => mergedar
+    end
+    Dataset(;ars...)
+end
+
 
 """
 open_dataset(g; driver=:all)
@@ -345,44 +402,46 @@ Open the dataset at `g` with the given `driver`.
 The default driver will search for available drivers and tries to detect the useable driver from the filename extension.
 """
 function open_dataset(g; driver = :all)
-    g = YAXArrayBase.to_dataset(g, driver = driver)
-    isempty(get_varnames(g)) && throw(ArgumentError("Group does not contain datasets."))
-    dimlist = collectdims(g)
-    dnames = string.(keys(dimlist))
-    varlist = filter(get_varnames(g)) do vn
-        upname = uppercase(vn)
-        !occursin("BNDS", upname) &&
-        !occursin("BOUNDS", upname) &&
-        !any(i -> isequal(upname, uppercase(i)), dnames)
-    end
-    allcubes = OrderedDict{Symbol,YAXArray}()
-    for vname in varlist
-        vardims = get_var_dims(g, vname)
-        iax = tuple(collect(dimlist[vd].ax for vd in vardims)...)
-        offs = [dimlist[vd].offs for vd in vardims]
-        subs = if all(iszero, offs)
-            nothing
-        else
-            ntuple(i -> (offs[i]+1):(offs[i]+length(iax[i])), length(offs))
-        end
-        ar = get_var_handle(g, vname)
-        att = get_var_attrs(g, vname)
-        if subs !== nothing
-            ar = view(ar, subs...)
+    dsopen = YAXArrayBase.to_dataset(g, driver = driver)
+    YAXArrayBase.open_dataset_handle(dsopen) do g 
+        isempty(get_varnames(g)) && throw(ArgumentError("Group does not contain datasets."))
+        dimlist = collectdims(g)
+        dnames = string.(keys(dimlist))
+        varlist = filter(get_varnames(g)) do vn
+            upname = uppercase(vn)
+            !occursin("BNDS", upname) &&
+            !occursin("BOUNDS", upname) &&
+            !any(i -> isequal(upname, uppercase(i)), dnames)
         end
-        if !haskey(att, "name")
-            att["name"] = vname
-        end
-        atts = propfromattr(att)
-        if any(in(keys(atts)), ["missing_value", "scale_factor", "add_offset"])
-            ar = CFDiskArray(ar, atts)
+        allcubes = OrderedDict{Symbol,YAXArray}()
+        for vname in varlist
+            vardims = get_var_dims(g, vname)
+            iax = tuple(collect(dimlist[vd].ax for vd in vardims)...)
+            offs = [dimlist[vd].offs for vd in vardims]
+            subs = if all(iszero, offs)
+                nothing
+            else
+                ntuple(i -> (offs[i]+1):(offs[i]+length(iax[i])), length(offs))
+            end
+            ar = get_var_handle(g, vname,persist=true)
+            att = get_var_attrs(g, vname)
+            if subs !== nothing
+                ar = view(ar, subs...)
+            end
+            if !haskey(att, "name")
+                att["name"] = vname
+            end
+            atts = propfromattr(att)
+            if any(in(keys(atts)), ["missing_value", "scale_factor", "add_offset"])
+                ar = CFDiskArray(ar, atts)
+            end
+            allcubes[Symbol(vname)] = YAXArray(iax, ar, atts, cleaner = CleanMe[])
         end
-        allcubes[Symbol(vname)] = YAXArray(iax, ar, atts, cleaner = CleanMe[])
+        gatts = YAXArrayBase.get_global_attrs(g)
+        gatts = Dict{String,Any}(string(k)=>v for (k,v) in gatts)
+        sdimlist = Dict(DD.name(v.ax) => v.ax for (k, v) in dimlist)
+        Dataset(allcubes, sdimlist,gatts)
     end
-    gatts = YAXArrayBase.get_global_attrs(g)
-    gatts = Dict{String,Any}(string(k)=>v for (k,v) in gatts)
-    sdimlist = Dict(DD.name(v.ax) => v.ax for (k, v) in dimlist)
-    Dataset(allcubes, sdimlist,gatts)
 end
 #Base.getindex(x::Dataset; kwargs...) = subsetcube(x; kwargs...)
 YAXDataset(; kwargs...) = Dataset(YAXArrays.YAXDefaults.cubedir[]; kwargs...)

test/DAT/mapcube.jl

@@ -62,6 +62,7 @@
     end
 
     @testset "Error shown in parallel" begin
+        import Zarr
         x,y,z = X(1:4), Y(1:5), Z(1:6)
         a1 = YAXArray((x,y,z), rand(4,5,6))
         indims = InDims("x")