Got ArgumentError: Type must be isbitstype when code with MPI

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1

Hi guys,

I got an ArgumentError: Type must be isbitstype when I tried to work with MPI.jl.

Here is a piece of code:

for row in eachrow(init_ele)
    println(i)
    send_mesg = vec(convert(Array, row))
    println(send_mesg)
    MPI.Send(send_mesg, i, tag, comm)
    i += 1
end

The init_ele is a DataFrame, so send_mesg is a 1D array.

I thought I got the error because Array is not isbitstype. If so, how could I send data in MPI?

Any help is welcome, thank you!

2

You probably got that error because the element type of the array is not isbitstype, not the array itself.

What is eltype(send_mesg)?

3

It is Union{Missing, Float64}.

I have some NaN in the DataFrame…

4

In that particular case, if you don’t mind the extra allocations, you can convert missings to actual NaNs, which are Float64.

For example:

send_mesg = [ismissing(x) ? NaN : x for x in row]

It’s not very elegant, but it should work with MPI if your data is Union{Missing, Float64}.

Similarly, you may convert the NaNs back to missing after receiving the data.

5

That’s a good idea!

Just modify your code slightly to send_mesg = Array([ismissing(x) ? x = NaN : x for x in row]) because I got MethodError: Cannot convert an object of type Missing to an object of type Float64 if use oftype() function.

Then the missings were converted to NaNs, and eltype(send_mesg) became Real.

But I still got ArgumentError: Type must be isbitstype even so… Any ideas?

6

Sorry, oftype was used incorrectly. I just edited my previous post.

Still, if you have an array of Union{Missing, Float64}, say

row = [3.0, 1.2, missing, 3.1]

then the above code (that I just edited) should give you a Vector{Float64}.

If you got an array of Real, it’s probably because your original data is not Float64, but a different subtype of Real such as Int, and then you’re mixing Ints and Float64s. In that case, you can try the following:

send_mesg = Float64[ismissing(x) ? NaN : x for x in row]
1 Like
7

It solved the problem, thank you very much!