How to use serde to serialize structs containing ndarray fields?

Question

I'm rather new to Rust, but was looking to use it for some numerics work and started exploring the ndarray crate a bit. Doing so, however, I got a bit stumped trying to derive serde::Serialize and serde::Deserialize for structs containing arrays.

In particular, I tried to compile the following snippet but got an error in doing so:

extern crate serde;
use ndarray::{ Array1 };
use serde::{ Serialize, Deserialize };

#[derive(Serialize, Deserialize)]
pub struct Canary {
    pub xs: Array1<f64>
}

error[E0277]: the trait bound `ndarray::ArrayBase<ndarray::OwnedRepr<f64>, ndarray::Dim<[usize; 1]>>: serde::Serialize` is not satisfied
  --> src/lib.rs:40:5
   |
40 |     pub xs: Array1<f64>
   |     ^^^ the trait `serde::Serialize` is not implemented for `ndarray::ArrayBase<ndarray::OwnedRepr<f64>, ndarray::Dim<[usize; 1]>>`
   |
   = note: required by `serde::ser::SerializeStruct::serialize_field`

# Cargo.toml
[dependencies]
ndarray = { version = "0.12.1", features = ["serde"] }
serde = { version = "1.0", features = ["derive"] }

Looking at the bounds on impl<A, D, S> Serialize for ArrayBase<S, D> where A: Serialize, D: Dimension + Serialize, S: Data<Elem = A>, I'm a bit confused as to what the error is, since A = f64 implements Serialize, and since D = Dim<[usize; 1]> implements both Dimension and Serialize. Is there something I'm missing in order to derive serialization for structs containing arrays? Thanks!

Does switching ndarray to version 0.13.1 have any effect? — Locke
@Locke: That solved it, thank you! Would you be willing to post that as an answer so that I can mark it as correct and give you the karma? — Chris Granade

Ibraheem Ahmed Ibraheem Ahmed · Accepted Answer · 2020-10-31T16:51:45

The latest version of ndarray is 0.13.1.

Updating the version in your Cargo.toml should fix the issue:

[dependencies]
ndarray = { version = "0.13.1", features = ["serde"] }

This answer was suggested by @Locke in a comment. I just created a small answer for future visitors.

How to use serde to serialize structs containing ndarray fields?

1 Answers