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Merge pull request #580 from LukeMathWalker/mean
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Mean
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@jturner314
jturner314 authored Mar 26, 2019
2 parents c569f75 + 64b3da7 commit 47b2691
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Showing 6 changed files with 250 additions and 181 deletions.
1 change: 1 addition & 0 deletions Cargo.toml
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Expand Up @@ -47,6 +47,7 @@ serde = { version = "1.0", optional = true }
defmac = "0.2"
quickcheck = { version = "0.7.2", default-features = false }
rawpointer = "0.1"
approx = "0.3"

[features]
# Enable blas usage
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4 changes: 2 additions & 2 deletions examples/column_standardize.rs
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Expand Up @@ -23,9 +23,9 @@ fn main() {
[ 2., 2., 2.]];

println!("{:8.4}", data);
println!("{:8.4} (Mean axis=0)", data.mean_axis(Axis(0)));
println!("{:8.4} (Mean axis=0)", data.mean_axis(Axis(0)).unwrap());

data -= &data.mean_axis(Axis(0));
data -= &data.mean_axis(Axis(0)).unwrap();
println!("{:8.4}", data);

data /= &std(&data, Axis(0));
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52 changes: 43 additions & 9 deletions src/numeric/impl_numeric.rs
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Expand Up @@ -46,6 +46,33 @@ impl<A, S, D> ArrayBase<S, D>
sum
}

/// Returns the [arithmetic mean] x̅ of all elements in the array:
///
/// ```text
/// 1 n
/// x̅ = ― ∑ xᵢ
/// n i=1
/// ```
///
/// If the array is empty, `None` is returned.
///
/// **Panics** if `A::from_usize()` fails to convert the number of elements in the array.
///
/// [arithmetic mean]: https://en.wikipedia.org/wiki/Arithmetic_mean
pub fn mean(&self) -> Option<A>
where
A: Clone + FromPrimitive + Add<Output=A> + Div<Output=A> + Zero
{
let n_elements = self.len();
if n_elements == 0 {
None
} else {
let n_elements = A::from_usize(n_elements)
.expect("Converting number of elements to `A` must not fail.");
Some(self.sum() / n_elements)
}
}

/// Return the sum of all elements in the array.
///
/// *This method has been renamed to `.sum()` and will be deprecated in the
Expand Down Expand Up @@ -123,8 +150,9 @@ impl<A, S, D> ArrayBase<S, D>

/// Return mean along `axis`.
///
/// **Panics** if `axis` is out of bounds, if the length of the axis is
/// zero and division by zero panics for type `A`, or if `A::from_usize()`
/// Return `None` if the length of the axis is zero.
///
/// **Panics** if `axis` is out of bounds or if `A::from_usize()`
/// fails for the axis length.
///
/// ```
Expand All @@ -133,19 +161,25 @@ impl<A, S, D> ArrayBase<S, D>
/// let a = arr2(&[[1., 2., 3.],
/// [4., 5., 6.]]);
/// assert!(
/// a.mean_axis(Axis(0)) == aview1(&[2.5, 3.5, 4.5]) &&
/// a.mean_axis(Axis(1)) == aview1(&[2., 5.]) &&
/// a.mean_axis(Axis(0)).unwrap() == aview1(&[2.5, 3.5, 4.5]) &&
/// a.mean_axis(Axis(1)).unwrap() == aview1(&[2., 5.]) &&
///
/// a.mean_axis(Axis(0)).mean_axis(Axis(0)) == aview0(&3.5)
/// a.mean_axis(Axis(0)).unwrap().mean_axis(Axis(0)).unwrap() == aview0(&3.5)
/// );
/// ```
pub fn mean_axis(&self, axis: Axis) -> Array<A, D::Smaller>
pub fn mean_axis(&self, axis: Axis) -> Option<Array<A, D::Smaller>>
where A: Clone + Zero + FromPrimitive + Add<Output=A> + Div<Output=A>,
D: RemoveAxis,
{
let n = A::from_usize(self.len_of(axis)).expect("Converting axis length to `A` must not fail.");
let sum = self.sum_axis(axis);
sum / &aview0(&n)
let axis_length = self.len_of(axis);
if axis_length == 0 {
None
} else {
let axis_length = A::from_usize(axis_length)
.expect("Converting axis length to `A` must not fail.");
let sum = self.sum_axis(axis);
Some(sum / &aview0(&axis_length))
}
}

/// Return variance along `axis`.
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169 changes: 0 additions & 169 deletions tests/array.rs
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Expand Up @@ -925,175 +925,6 @@ fn assign()
assert_eq!(a, arr2(&[[0, 0], [3, 4]]));
}

#[test]
fn sum_mean()
{
let a = arr2(&[[1., 2.], [3., 4.]]);
assert_eq!(a.sum_axis(Axis(0)), arr1(&[4., 6.]));
assert_eq!(a.sum_axis(Axis(1)), arr1(&[3., 7.]));
assert_eq!(a.mean_axis(Axis(0)), arr1(&[2., 3.]));
assert_eq!(a.mean_axis(Axis(1)), arr1(&[1.5, 3.5]));
assert_eq!(a.sum_axis(Axis(1)).sum_axis(Axis(0)), arr0(10.));
assert_eq!(a.view().mean_axis(Axis(1)), aview1(&[1.5, 3.5]));
assert_eq!(a.sum(), 10.);
}

#[test]
fn sum_mean_empty() {
assert_eq!(Array3::<f32>::ones((2, 0, 3)).sum(), 0.);
assert_eq!(Array1::<f32>::ones(0).sum_axis(Axis(0)), arr0(0.));
assert_eq!(
Array3::<f32>::ones((2, 0, 3)).sum_axis(Axis(1)),
Array::zeros((2, 3)),
);
let a = Array1::<f32>::ones(0).mean_axis(Axis(0));
assert_eq!(a.shape(), &[]);
assert!(a[()].is_nan());
let a = Array3::<f32>::ones((2, 0, 3)).mean_axis(Axis(1));
assert_eq!(a.shape(), &[2, 3]);
a.mapv(|x| assert!(x.is_nan()));
}

#[test]
fn var_axis() {
let a = array![
[
[-9.76, -0.38, 1.59, 6.23],
[-8.57, -9.27, 5.76, 6.01],
[-9.54, 5.09, 3.21, 6.56],
],
[
[ 8.23, -9.63, 3.76, -3.48],
[-5.46, 5.86, -2.81, 1.35],
[-1.08, 4.66, 8.34, -0.73],
],
];
assert!(a.var_axis(Axis(0), 1.5).all_close(
&aview2(&[
[3.236401e+02, 8.556250e+01, 4.708900e+00, 9.428410e+01],
[9.672100e+00, 2.289169e+02, 7.344490e+01, 2.171560e+01],
[7.157160e+01, 1.849000e-01, 2.631690e+01, 5.314410e+01]
]),
1e-4,
));
assert!(a.var_axis(Axis(1), 1.7).all_close(
&aview2(&[
[0.61676923, 80.81092308, 6.79892308, 0.11789744],
[75.19912821, 114.25235897, 48.32405128, 9.03020513],
]),
1e-8,
));
assert!(a.var_axis(Axis(2), 2.3).all_close(
&aview2(&[
[ 79.64552941, 129.09663235, 95.98929412],
[109.64952941, 43.28758824, 36.27439706],
]),
1e-8,
));

let b = array![[1.1, 2.3, 4.7]];
assert!(b.var_axis(Axis(0), 0.).all_close(&aview1(&[0., 0., 0.]), 1e-12));
assert!(b.var_axis(Axis(1), 0.).all_close(&aview1(&[2.24]), 1e-12));

let c = array![[], []];
assert_eq!(c.var_axis(Axis(0), 0.), aview1(&[]));

let d = array![1.1, 2.7, 3.5, 4.9];
assert!(d.var_axis(Axis(0), 0.).all_close(&aview0(&1.8875), 1e-12));
}

#[test]
fn std_axis() {
let a = array![
[
[ 0.22935481, 0.08030619, 0.60827517, 0.73684379],
[ 0.90339851, 0.82859436, 0.64020362, 0.2774583 ],
[ 0.44485313, 0.63316367, 0.11005111, 0.08656246]
],
[
[ 0.28924665, 0.44082454, 0.59837736, 0.41014531],
[ 0.08382316, 0.43259439, 0.1428889 , 0.44830176],
[ 0.51529756, 0.70111616, 0.20799415, 0.91851457]
],
];
assert!(a.std_axis(Axis(0), 1.5).all_close(
&aview2(&[
[ 0.05989184, 0.36051836, 0.00989781, 0.32669847],
[ 0.81957535, 0.39599997, 0.49731472, 0.17084346],
[ 0.07044443, 0.06795249, 0.09794304, 0.83195211],
]),
1e-4,
));
assert!(a.std_axis(Axis(1), 1.7).all_close(
&aview2(&[
[ 0.42698655, 0.48139215, 0.36874991, 0.41458724],
[ 0.26769097, 0.18941435, 0.30555015, 0.35118674],
]),
1e-8,
));
assert!(a.std_axis(Axis(2), 2.3).all_close(
&aview2(&[
[ 0.41117907, 0.37130425, 0.35332388],
[ 0.16905862, 0.25304841, 0.39978276],
]),
1e-8,
));

let b = array![[100000., 1., 0.01]];
assert!(b.std_axis(Axis(0), 0.).all_close(&aview1(&[0., 0., 0.]), 1e-12));
assert!(
b.std_axis(Axis(1), 0.).all_close(&aview1(&[47140.214021552769]), 1e-6),
);

let c = array![[], []];
assert_eq!(c.std_axis(Axis(0), 0.), aview1(&[]));
}

#[test]
#[should_panic]
fn var_axis_negative_ddof() {
let a = array![1., 2., 3.];
a.var_axis(Axis(0), -1.);
}

#[test]
#[should_panic]
fn var_axis_too_large_ddof() {
let a = array![1., 2., 3.];
a.var_axis(Axis(0), 4.);
}

#[test]
fn var_axis_nan_ddof() {
let a = Array2::<f64>::zeros((2, 3));
let v = a.var_axis(Axis(1), ::std::f64::NAN);
assert_eq!(v.shape(), &[2]);
v.mapv(|x| assert!(x.is_nan()));
}

#[test]
fn var_axis_empty_axis() {
let a = Array2::<f64>::zeros((2, 0));
let v = a.var_axis(Axis(1), 0.);
assert_eq!(v.shape(), &[2]);
v.mapv(|x| assert!(x.is_nan()));
}

#[test]
#[should_panic]
fn std_axis_bad_dof() {
let a = array![1., 2., 3.];
a.std_axis(Axis(0), 4.);
}

#[test]
fn std_axis_empty_axis() {
let a = Array2::<f64>::zeros((2, 0));
let v = a.std_axis(Axis(1), 0.);
assert_eq!(v.shape(), &[2]);
v.mapv(|x| assert!(x.is_nan()));
}

#[test]
fn iter_size_hint()
{
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2 changes: 1 addition & 1 deletion tests/complex.rs
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Expand Up @@ -22,5 +22,5 @@ fn complex_mat_mul()
let r = a.dot(&e);
println!("{}", a);
assert_eq!(r, a);
assert_eq!(a.mean_axis(Axis(0)), arr1(&[c(1.5, 1.), c(2.5, 0.)]));
assert_eq!(a.mean_axis(Axis(0)).unwrap(), arr1(&[c(1.5, 1.), c(2.5, 0.)]));
}
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