Unable to import traits implementation from ndarray

[Riotpiaole]

Question

• Hi I run in a problem related with LeastSquare: I am trying to import the ndarray_linalg:: {LeastSquaresSvd, LeastSquaresSvdInto, LeastSquaresSvdInPlace} . And calling from ndarray::Array1::least_squares class.
  • However the rust compiler unable to import it.

Cargo setup

• The OS environment is running in WSL2 in windows 10

#Cargo.toml

...
[dependencies]
openblas-src = { version = "*", features = ["static"] }
ndarray = "0.12"
ndarray-linalg = { version = "0.12.0", features = ["openblas"] }
ndarray-stats = "0.3"
...

• code snippets to

// mod.rs 
extern crate ndarray_linalg;
extern crate ndarray;
extern crate openblas_src;
pub mod foo.
...

// foo.rs
use ndarray
use ndarray_linalg::{LeastSquaresSvd, LeastSquaresSvdInto, LeastSquaresSvdInPlace};
let a= array![
            [1., 1., 1.],
            [2., 3., 4.],
            [3., 5., 2.],
            [4., 2., 5.],
            [5., 4., 3.]
        ];
 // solving for a single right-hand 
let b = array![-10., 12., 14., 16., 18.];
// let res = a.least_squares(&b);

// using `least_squares_in_place` which overwrites its arguments
// let mut a_3 = a.clone();
// let mut b_3 = b.clone();
let (m, n) = (a.shape()[0], a.shape()[1]);
let solution = b.slice(s![0..n]).to_owned();
let result = a.least_squares(&b); // unable to find  least_squares 
...

• The error outputs

  --> keyboard-analyzer/src/models/structural_break_analysis/chow.rs:19:22
   |
19 | use ndarray_linalg::{LeastSquaresSvd, LeastSquaresSvdInto, LeastSquaresSvdInPlace};
 ....

method not found in `ndarray::ArrayBase<models::structural_break_analysis::ndarray::OwnedRepr<{float}>, 
   models::structural_break_analysis::ndarray::Dim<[usize; 2]>>`

[termoshtt]

Can you call other methods, e.g. qr?

ndarray-linalg = { version = "0.12.0", features = ["openblas"] }

least_squares is added in 0.12.1. Try cargo update

If you cannot call least_squares while can call qr on 0.12.1, it may be fixed by #227. I will release this fix as 0.12.2.

[Riotpiaole]

Thanks. So like this?

...
let result =  a.qr(&b);
...

• but still doesn't work.

[Riotpiaole]

I figured, Yeah still didn't work

let result = a.qr_square_inplace(&b);

[jturner314]

The paths in the type ndarray::ArrayBase<models::structural_break_analysis::ndarray::OwnedRepr<{float}>, models::structural_break_analysis::ndarray::Dim<[usize; 2]>> in the error message are a little weird because ndarray is referenced in two different ways: ndarray and models::structural_break_analysis::ndarray. It's also surprising that the error message identifies 19 | use ndarray_linalg::{LeastSquaresSvd, LeastSquaresSvdInto, LeastSquaresSvdInPlace}; as the problematic line, instead of the line where .least_squares() is being called.

Are those extern crate lines in a module within the crate (not the top-level lib.rs or main.rs)? I don't think I've seen anyone do that before. It may be worth updating to Rust 2018 edition and removing the extern crate lines.

[Riotpiaole]

• The problem is i am not sure which implementation is correct.
• I am struggling to figure out a way make sure some trait implementations works by use

[jacobbond]

I seem to be having a similar issue, even when pulling the current code from GitHub (which it pulls as ndarray-linalg v0.13.0-alpha.0):

Cargo.toml:

...
ndarray = "0.14"
ndarray-linalg = { git = "https://github.com/rust-ndarray/ndarray-linalg", features = ["openblas"] }
...

main.rs:

use ndarray::{array, Array1, Array2};
use ndarray_linalg::{LeastSquaresSvd, LeastSquaresSvdInto, LeastSquaresSvdInPlace};

fn main() {
...
let result = a.least_squares(&b);
}

My error is:

error[E0599]: no method named least_squares found for struct ndarray::ArrayBase<ndarray::OwnedRepr<f64>, ndarray::Dim<[usize; 2]>> in the current scope
--> src/main.rs:23:20
|
23 | let result = a.least_squares(&b).unwrap();
| ^^^^^^^^^^^^^ method not found in ndarray::ArrayBase<ndarray::OwnedRepr<f64>, ndarray::Dim<[usize; 2]>>

I get this also when trying a.qr(&b).

[RustyBamboo]

@jacobbond I had the same issue. It seems to because of mismatching (out-of-date) dependencies between the ndarray-* crates. For now, setting my dependencies in Cargo.toml to following fixed the issue for me:

[dependencies]
num-complex = "0.2.4"
approx = {version = "0.3.2", features = ["num-complex"]}
ndarray = {version = "0.13", features = ["approx"]}
ndarray-linalg = { version = "0.12", features = ["openblas-static"] }