Data update

Task/Undefined-values/Julia/undefined-values.jl

@@ -0,0 +1,28 @@
+julia> arr = [1, 2, nothing, 3]
+4-element Array{Union{Nothing, Int64},1}:
+ 1
+ 2
+  nothing
+ 3
+
+julia> x = arr .+ 5
+ERROR: MethodError: no method matching +(::Nothing, ::Int64)
+Closest candidates are:
+  +(::Any, ::Any, ::Any, ::Any...) at operators.jl:502
+  +(::Complex{Bool}, ::Real) at complex.jl:292
+  +(::Missing, ::Number) at missing.jl:93
+  ...
+
+julia> arr = [1, 2, missing, 3]
+4-element Array{Union{Missing, Int64},1}:
+ 1
+ 2
+  missing
+ 3
+
+julia> x = arr .+ 5
+4-element Array{Union{Missing, Int64},1}:
+ 6
+ 7
+  missing
+ 8