fix bug when vector empty

src/pma.jl

@@ -84,7 +84,7 @@ function PackedMemoryArray(keys::Vector{K}, values::Vector{T}; sort = true) wher
 end
 
 function PackedMemoryArray(::Type{K}, ::Type{T}) where {K,T} # empty pma
-    expected_nb_elems = 20
+    expected_nb_elems = 100
     t_h, t_0, p_h, p_0 = 0.7, 0.92, 0.3, 0.08
     capacity = 2^ceil(Int, log2(ceil(expected_nb_elems/t_h)))
     array = Elements{K,T}(nothing, capacity)
@@ -177,7 +177,7 @@ function _look_for_rebalance!(pma::PackedMemoryArray, pos::Int)
     if density > t 
         _extend!(pma)
     end
-    if density < p
+    if density < p && pma.height > 1
         # We must pack before shrinking otherwise we loose data
         pack!(pma.array, 1, length(pma.array)/2, nb_cells)
         _shrink!(pma)

test/functional/functionaltests.jl

@@ -5,6 +5,7 @@ function functional_tests()
     # Dynamic Sparse Vector (pma)
     @testset "dynsparsevector (PackedMemoryArray) - func - simple use" begin
         dynsparsevec_simple_use()
+        dynsparsevec_fill_empty()
     end
     @testset "Insertions & finds in dyn sparse vector - performance" begin
         dynsparsevec_insertions_and_gets()

test/functional/sparsevector.jl

@@ -62,6 +62,39 @@ function dynsparsevec_simple_use()
     return
 end
 
+function fill(vec, kv)
+    n = 0
+    for (k, v) in kv
+        vec[k] = v
+        n += 1
+        @test vec.nb_elements == n
+    end
+    return
+end
+
+function empty(vec, kv)
+    n = length(kv)
+    for (k, v) in kv
+        vec[k] = 0.0
+        n -= 1
+        @test vec.nb_elements == n
+    end
+    return
+end
+
+function dynsparsevec_fill_empty()
+    # Start with an empty sparse vector
+    vec = dynamicsparsevec(Int[], Float64[])
+    for n in [20, 100, 1000, 10000, 100000]
+        kv = Dict{Int, Float64}(
+            rand(rng, 1:10000000000) => rand(rng, 1:0.1:10000) for i in 1:n
+        )
+        fill(vec, kv)
+        empty(vec, kv)
+    end
+    return
+end
+
 function dynsparsevec_insertions_and_gets()
     kv1 = Dict{Int, Float64}(
         rand(rng, 1:10000000000) => rand(rng, 1:0.1:10000) for i in 1:1000000