# Write structure to HDF5 file and read a compound type from HDF5 into Julia structure

**URL:** <https://discourse.julialang.org/t/write-structure-to-hdf5-file-and-read-a-compound-type-from-hdf5-into-julia-structure/20358>\
**Category:** General Usage\
**Tags:** hdf5\
**Created:** [February 1, 2019, 4:04pm UTC](https://discourse.julialang.org/t/write-structure-to-hdf5-file-and-read-a-compound-type-from-hdf5-into-julia-structure/20358 "2019-02-01T16:04:27Z")\
**Posts on this page:** 1\
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**Author:** ![jacob-roth](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jacob-roth/32/1862_2.png) [@jacob-roth](https://discourse.julialang.org/u/jacob-roth)\
**Post date:** [June 18, 2019, 1:58am UTC](https://discourse.julialang.org/t/write-structure-to-hdf5-file-and-read-a-compound-type-from-hdf5-into-julia-structure/20358/4 "2019-06-18T01:58:17Z")

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How can I save an array of arrays in HDF5? In particular, I’m trying to save an array of `Set`s, but HDF5 can’t save a `Set`, so I tried converting to an array, but I still cant save an array of arrays. I’m trying `HDF5` over `JLD2` because of what I think are similar mapping / serialization issues referenced [here](https://github.com/JuliaIO/JLD2.jl/issues/55)…

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