Binary operation for ArrayView

[termoshtt]

I'm confusing errors arising around +.

let dist = Range::new(0, 1);
let a = Array::<f64, _>::random((5, 5));
let x0 = Array::<f64, _>::random(5);
let xs: Vec<_> = a.axis_iter(Axis(0)).map(|x| x + &x0);

I expect that x + &x0 produces new array since document says

&A @ &A which produces a new Array

But it produces an error:

error[E0369]: binary operation `+` cannot be applied to type `ndarray::ArrayBase<ndarray::ViewRepr<&f64>, usize>` 

After struggling, I find it works when I rewrite the last line as following:

let xs: Vec<_> = a.axis_iter(Axis(0)).map(|x| x.to_owned() + &x0);

I hope the first my code works. Is there any technical problem to implement Add for ArrayView?

[bluss]

x in x + &x0 is an array view, which is an "A", not an "&A". So &x + &x0 should work.

[termoshtt]

Oh...
I now understand my mistake and what document says.
The above error message means ArrayView cannot be consumed. It is hard to read :<

Thanks for your help!

[bluss]

It's a bit unfortunate that one needs to pass &ArrayView in many places where just passing a view by value should be enough. It's partly due to missing support for custom view types in Rust. Feel free to report any issues you find with ndarray.