Hi, So I have an vector of tuples of floats, i.e.: Array{Tuple{Float64,Float64},1}(). I know that tuples are immutables and so theoretically this array should be contiguous in memory and there should be no pointers in the vector or the tuples. Is this true? And more generally is there a way that I …

You could try something like that: x = Array{Tuple{Float64,Float64},1}() push!(x,(1.,1.),(2.,2.),(3.,3.)) ptr = pointer(x) offset = sizeof(x[1]) unsafe_load(ptr) unsafe_load(ptr+offset) unsafe_load(ptr+2offset)

You can get a pointer to the n-th element of a vector v using pointer(v,n). The difference between two consecutive indices gives accordingly the size occupied by one element in the vector. You can then compare that to the actual size of the elements of v: v = Vector( [(1., 2., 3.), (4., 5., 6.), (7…

[image] m-j-w: Base.iscontiguous(v) This does not tell you if there’s indirection. If you want to programatically check if an Array has no indirection, isbits(eltype(v)) should tell you. If you want to verify/see it yourself, you can use the unsafe_load in @jonathanBieler ’s answer to check. …

True. Further, d == sizeof(eltype(v)) would give a false positive if eltype(v) were mutable and sizeof(eltype(v)) were of size of a pointer… A generalization of Base.iscontigous might indeed be quite useful.

Base.iscontiguous is not meant for this. It’s only for indexing.

Looks like isbits(eltype(x)) works for this particular case and the unsafe_load method works in general. Thanks for the prompt answers everyone.

[image] vipstar: unsafe_load method works in general. Just to be clear that you should not use this in real code. You can get a segfault if you made the wrong guess.

I love the manually digging through memory approach. And for those who want an easier way, @tkf told me about Base.allocatedinline which does precisely this. When will a vector of structs be contiguous in memory? - #2 by tkf

If I’m not mistaken, it should be isbitstype(eltype(x)) instead of isbits(eltype(x)).

Checking if a vector of structs is contiguous in memory

General Usage

vipstar March 19, 2017, 5:07pm 9

Oh yes I got that. I just wanted to check that this data structure is continguous to make sure it won’t be too slow.

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Checking if a vector of structs is contiguous in memory

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