Improve Error message when `dim` in `bitinformation(data, dim)` too short about bitinformation.jl HOT 3 OPEN

I just add to this that I could imagine that BitInformation.jl would raise a user defined error, which could be as simple as

    type DimensionalityError <: Exception
    end
    type DimensionalityErrorTree <: Exception
        var::String
    end

    Base.showerror(io::IO, e:: DimensionalityErrorTree) = print(io, "You try to calculate bitinformation along a (too) short dimension of",e.var, "elements.")

    julia> throw(DimensionalityError(Len(data[dim])))

Not sure if this is the correct syntax. I just adapted it from here.

This would be easier to catch from calling scripts.

from bitinformation.jl.

At the moment we are doing

julia> using BitInformation
julia> A = rand(100);
julia> mask = A .== A;
julia> bitinformation(A,mask)
ERROR: AssertionError: Mask has 0 unmasked values, 0 entries are adjacent.
Stacktrace:
 [1] bitinformation(A::Vector{Float64}, mask::BitVector; dim::Int64, set_zero_insignificant::Bool, confidence::Float64)
   @ BitInformation ~/.julia/packages/BitInformation/VpaaY/src/mutual_information.jl:105
...

Julia has a bunch of error types. I agree that an AssertionError is maybe not the most telling and that we may want to reconsider what kind of error is thrown. However, it seems that this AssertionError is only propagated as a string in the error message (why are python error messages always sooo long 😄) probably because the python errors are not matched to julia errors. Meaning that whether we decide for another error type or define our own, this would only be of use if you could actually catch that error somehow. And what do you want to do with it if you catch it?

from bitinformation.jl.

You try to calculate bitinformation along a (too) short dimension of {length(data[dim])} elements. Maybe even continuing ... bitinformation assumes that adjacents analysis elements are also physically adjacent...

Feel free to suggest error messages. I'd rather have it short and on the point though. I don't think it's the job of an error message to explain how a function is used though, this should be part of the docstring / documentation. On that note I don't think the masked array support ever made it into the documentation ... 😞

from bitinformation.jl.