add FHist.jl and option to parse directly to FHist.jl objects (#294)

* add FHist

* extend function of `UnROOT.parseTH()`

Project.toml

@@ -10,6 +10,7 @@ BitIntegers = "c3b6d118-76ef-56ca-8cc7-ebb389d030a1"
 CodecLz4 = "5ba52731-8f18-5e0d-9241-30f10d1ec561"
 CodecXz = "ba30903b-d9e8-5048-a5ec-d1f5b0d4b47b"
 CodecZstd = "6b39b394-51ab-5f42-8807-6242bab2b4c2"
+FHist = "68837c9b-b678-4cd5-9925-8a54edc8f695"
 HTTP = "cd3eb016-35fb-5094-929b-558a96fad6f3"
 IterTools = "c8e1da08-722c-5040-9ed9-7db0dc04731e"
 LRUCache = "8ac3fa9e-de4c-5943-b1dc-09c6b5f20637"
@@ -33,6 +34,7 @@ BitIntegers = "^0.2.6, ^0.3"
 CodecLz4 = "^0.3, ^0.4"
 CodecXz = "^0.6, ^0.7"
 CodecZstd = "^0.6, ^0.7, ^0.8"
+FHist = "0.10"
 HTTP = "^0.9.7, 1"
 IterTools = "^1"
 LRUCache = "^1.3.0"

src/UnROOT.jl

@@ -11,7 +11,7 @@ reinterpret(a,b) = Base.reinterpret(a,b)
 
 import AbstractTrees: children, printnode, print_tree
 
-using CodecLz4, CodecXz, CodecZstd, StaticArrays, LorentzVectors, ArraysOfArrays
+using CodecLz4, CodecXz, CodecZstd, StaticArrays, LorentzVectors, ArraysOfArrays, FHist
 using Mixers, Parameters, Memoization, LRUCache
 import IterTools: groupby
 

src/utils.jl

@@ -86,20 +86,36 @@ function JaggType(f, branch, leaf)
 end
 
 """
-    parseTH(th::Dict{Symbol, Any})
+    parseTH(th::Dict{Symbol, Any}; raw=true) -> (counts, edges, sumw2, nentries)
+    parseTH(th::Dict{Symbol, Any}; raw=false) -> Union{FHist.Hist1D, FHist.Hist2D}
 
-Parse the output of [`TH`](@ref) into a tuple of `counts`, `edges`, and `sumw2`.
-A `StatsBase.Histogram` can then be constructed with `Histogram(edges, counts)`.
-TH1 and TH2 inputs are supported.
+When `raw=true`, parse the output of [`TH`](@ref) into a tuple of `counts`, `edges`, `sumw2`, and `nentries`.
+When `raw=false`, parse the output of [`TH`](@ref) into FHist.jl histograms.
+
+# Example
+```julia
+julia> UnROOT.parseTH(UnROOT.samplefile("histograms1d2d.root")["myTH1D"])
+([40.0, 2.0], (-2.0:2.0:2.0,), [800.0, 2.0], 4.0)
+
+julia> UnROOT.parseTH(UnROOT.samplefile("histograms1d2d.root")["myTH1D"]; raw=false)
+edges: -2.0:2.0:2.0
+bin counts: [40.0, 2.0]
+total count: 42.0
+```
+
+    !!! note
+    TH1 and TH2 inputs are supported.
 """
-function parseTH(th::Dict{Symbol, Any})
+function parseTH(th::Dict{Symbol, Any}; raw=true)
     xmin = th[:fXaxis_fXmin]
     xmax = th[:fXaxis_fXmax]
     xnbins = th[:fXaxis_fNbins]
     xbins = isempty(th[:fXaxis_fXbins]) ? range(xmin, xmax, length=xnbins+1) : th[:fXaxis_fXbins];
     counts = th[:fN]
+    nentries = th[:fEntries]
     sumw2 = th[:fSumw2]
-    if th[:fYaxis_fNbins] > 1
+    dimension = th[:fYaxis_fNbins]
+    if dimension > 1
         ymin = th[:fYaxis_fXmin]
         ymax = th[:fYaxis_fXmax]
         ynbins = th[:fYaxis_fNbins]
@@ -112,7 +128,13 @@ function parseTH(th::Dict{Symbol, Any})
         sumw2 = sumw2[2:end-1]
         edges = (xbins,)
     end
-    return counts, edges, sumw2
+    if raw
+        return counts, edges, sumw2, nentries
+    elseif dimension > 1
+        return Hist2D(FHist.Histogram(edges, counts),sumw2, nentries)
+    else
+        return Hist1D(FHist.Histogram(edges, counts),sumw2, nentries)
+    end
 end
 
 function samplefile(filename::AbstractString)

test/runtests.jl

@@ -1,5 +1,6 @@
 using Test
 using UnROOT, LorentzVectors
+using UnROOT.FHist
 using StaticArrays
 using InteractiveUtils
 using DataFrames, SHA
@@ -639,9 +640,20 @@ end
         @test f[k][:fN] == [0.0, 0.0, 0.0, 0.0, 0.0, 20.0, 1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 20.0, 1.0, 0.0, 0.0, 0.0, 0.0, 0.0]
     end
 
-    @test UnROOT.parseTH(f["myTH1F"]) == ([40.0, 2.0], (-2.0:2.0:2.0,), [800.0, 2.0])
-    @test UnROOT.parseTH(f["myTH2D"]) == ([20.0 0.0 0.0 20.0; 1.0 0.0 0.0 1.0], (-2.0:2.0:2.0, -2.0:1.0:2.0), [400.0 0.0 0.0 400.0; 1.0 0.0 0.0 1.0])
-    @test UnROOT.parseTH(f["myTH1D_nonuniform"]) == ([40.0, 2.0], ([-2.0, 1.0, 2.0],), [800.0, 2.0])
+    th1 = UnROOT.parseTH(f["myTH1F"];raw=false)
+    @test bincounts(th1) == [40.0, 2.0]
+    @test binedges(th1) == -2.0:2.0:2.0
+    @test th1.sumw2 == [800.0, 2.0]
+
+    th2 = UnROOT.parseTH(f["myTH2D"];raw=false)
+    @test bincounts(th2) == [20.0 0.0 0.0 20.0; 1.0 0.0 0.0 1.0]
+    @test binedges(th2) == (-2.0:2.0:2.0, -2.0:1.0:2.0)
+    @test th2.sumw2 == [400.0 0.0 0.0 400.0; 1.0 0.0 0.0 1.0]
+
+    th3 = UnROOT.parseTH(f["myTH1D_nonuniform"];raw=false)
+    @test bincounts(th3) == [40.0, 2.0]
+    @test binedges(th3) == [-2.0, 1.0, 2.0]
+    @test th3.sumw2 == [800.0, 2.0]
 
     close(f)