Don't assume that partialsort! partitions around the selected index

src/Sorting/nanmedian.jl

@@ -108,20 +108,20 @@ function _nanmedian!(A::AbstractArray{T}, ::Colon) where {T}
     n < 2 && return float(T)(A[iₗ])
     i½ = (iₗ + iᵤ) ÷ 2
     if iseven(n)
-        if n < 384
+        Aᵢ₋, Aᵢ₊ =  if n < 384
             quicksort!(A, iₗ, iᵤ)
+            A[i½], A[i½+1]
         else
-            quickselect!(A, iₗ, iᵤ, i½)
-            quickselect!(A, i½+1, iᵤ, i½+1)
+            quickselect!(A, iₗ, iᵤ, i½), quickselect!(A, iₗ, iᵤ, i½+1)
         end
-        return (A[i½] + A[i½+1]) / 2
+        return float(T)(0.5*Aᵢ₋ + 0.5*Aᵢ₊)
     else
         if n < 192
             quicksort!(A, iₗ, iᵤ)
         else
             quickselect!(A, iₗ, iᵤ, i½)
         end
-        return A[i½] / 1
+        return float(T)(A[i½])
     end
 end
 

src/Sorting/nanpctile.jl

@@ -182,14 +182,14 @@ function _nanquantile!(A::AbstractArray{T}, q::Real, ::Colon) where {T}
     iₚ = q*n₋ + iₗ
     iₚ₋ = floor(Int, iₚ)
     iₚ₊ = ceil(Int, iₚ)
-    if n₋ < 384
+    f = iₚ - iₚ₋
+    Aᵢ₋, Aᵢ₊ = if n₋ < 384
         quicksort!(A, iₗ, iᵤ)
+        A[iₚ₋], A[iₚ₊]
     else
-        quickselect!(A, iₗ, iᵤ, iₚ₋)
-        quickselect!(A, iₚ₊, iᵤ, iₚ₊)
+        quickselect!(A, iₗ, iᵤ, iₚ₋), quickselect!(A, iₗ, iᵤ, iₚ₊)
     end
-    f = iₚ - iₚ₋
-    return f*A[iₚ₊] + (1-f)*A[iₚ₋]
+    return f*Aᵢ₊ + (1-f)*Aᵢ₋
 end
 
 # Generate customized set of loops for a given ndims and a vector