The Statistics package mean function returns missing if any elements of an array are missing.
julia> using Statistics
julia> mean([1 2 3 4 5] )
3.0
julia> mean([1 2 missing 4 5] ) # Note missing value
missing
How do I get the mean of the non-missing values?
The skipmissing function will send only the non-missing elements to the mean function:
julia> using Statistics
julia> mean([1 2 3 4 5] )
3.0https://docs.julialang.org/en/stable/manual/missing/#Skipping-Missing-Values-1
julia> mean([1 2 missing 4 5] ) # Note missing value
missing
# Here is the answer:
julia> mean(skipmissing([1 2 missing 4 missing] ))
2.3333333333333335
As pointed out by @Milan Bouchet-Valat in a comment to the question, the docs on missing are here. They are a good quick, first read on Julia's handling of missing values.