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Merged
merged 4 commits into from
Sep 2, 2018
Merged

Add more interpolation strategies #2

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e90555e
Implemented Midpoint. Refactored code to change types of variables.
LukeMathWalker Sep 2, 2018
1d094e8
Defined Linear.
LukeMathWalker Sep 2, 2018
f5f77ea
Added Interpolate implementation for Linear.
LukeMathWalker Sep 2, 2018
ff51479
Fixed docs!
LukeMathWalker Sep 2, 2018
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80 changes: 71 additions & 9 deletions src/numeric/impl_numeric.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,8 +6,8 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use std::ops::Add;
use libnum::{self, Zero, Float};
use std::ops::{Add, Sub, Div, Mul};
use libnum::{self, Zero, Float, FromPrimitive};
use itertools::free::enumerate;

use imp_prelude::*;
Expand All @@ -34,14 +34,25 @@ pub trait Interpolate<T> {
fn upper_index(q: f64, len: usize) -> usize {
Self::float_percentile_index(q, len).ceil() as usize
}

fn float_percentile_index_fraction(q: f64, len: usize) -> f64 {
Self::float_percentile_index(q, len) - (Self::lower_index(q, len) as f64)
}

fn needs_lower(q: f64, len: usize) -> bool;
fn needs_upper(q: f64, len: usize) -> bool;
fn interpolate(lower: Option<T>, upper: Option<T>, q: f64, len: usize) -> T;
fn interpolate<D>(lower: Option<Array<T, D>>,
upper: Option<Array<T, D>>,
q: f64,
len: usize) -> Array<T, D>
where D: Dimension;
}

pub struct Upper;
pub struct Lower;
pub struct Nearest;
pub struct Midpoint;
pub struct Linear;

impl<T> Interpolate<T> for Upper {
fn needs_lower(_q: f64, _len: usize) -> bool {
Expand All @@ -50,7 +61,10 @@ impl<T> Interpolate<T> for Upper {
fn needs_upper(_q: f64, _len: usize) -> bool {
true
}
fn interpolate(_lower: Option<T>, upper: Option<T>, _q: f64, _len: usize) -> T {
fn interpolate<D>(_lower: Option<Array<T, D>>,
upper: Option<Array<T, D>>,
_q: f64,
_len: usize) -> Array<T, D> {
upper.unwrap()
}
}
Expand All @@ -62,7 +76,10 @@ impl<T> Interpolate<T> for Lower {
fn needs_upper(_q: f64, _len: usize) -> bool {
false
}
fn interpolate(lower: Option<T>, _upper: Option<T>, _q: f64, _len: usize) -> T {
fn interpolate<D>(lower: Option<Array<T, D>>,
_upper: Option<Array<T, D>>,
_q: f64,
_len: usize) -> Array<T, D> {
lower.unwrap()
}
}
Expand All @@ -75,7 +92,10 @@ impl<T> Interpolate<T> for Nearest {
fn needs_upper(q: f64, len: usize) -> bool {
!<Self as Interpolate<T>>::needs_lower(q, len)
}
fn interpolate(lower: Option<T>, upper: Option<T>, q: f64, len: usize) -> T {
fn interpolate<D>(lower: Option<Array<T, D>>,
upper: Option<Array<T, D>>,
q: f64,
len: usize) -> Array<T, D> {
if <Self as Interpolate<T>>::needs_lower(q, len) {
lower.unwrap()
} else {
Expand All @@ -84,6 +104,48 @@ impl<T> Interpolate<T> for Nearest {
}
}

impl<T> Interpolate<T> for Midpoint
where T: Add<T, Output = T> + Div<T, Output = T> + Clone + FromPrimitive
{
fn needs_lower(_q: f64, _len: usize) -> bool {
true
}
fn needs_upper(_q: f64, _len: usize) -> bool {
true
}
fn interpolate<D>(lower: Option<Array<T, D>>,
upper: Option<Array<T, D>>,
_q: f64, _len: usize) -> Array<T, D>
where D: Dimension
{
let denom = T::from_u8(2).unwrap();
(lower.unwrap() + upper.unwrap()).mapv_into(|x| x / denom.clone())
}
}

impl<T> Interpolate<T> for Linear
where T: Add<T, Output = T> + Sub<T, Output = T> + Mul<T, Output = T> + Clone + FromPrimitive
{
fn needs_lower(_q: f64, _len: usize) -> bool {
true
}
fn needs_upper(_q: f64, _len: usize) -> bool {
true
}
fn interpolate<D>(lower: Option<Array<T, D>>,
upper: Option<Array<T, D>>,
q: f64, len: usize) -> Array<T, D>
where D: Dimension
{
let fraction = T::from_f64(
<Self as Interpolate<T>>::float_percentile_index_fraction(q, len)
).unwrap();
let a = lower.unwrap().mapv_into(|x| x * fraction.clone());
let b = upper.unwrap().mapv_into(|x| x * (T::from_u8(1).unwrap() - fraction.clone()));
a + b
}
}

/// Numerical methods for arrays.
impl<A, S, D> ArrayBase<S, D>
where S: Data<Elem=A>,
Expand Down Expand Up @@ -187,8 +249,8 @@ impl<A, S, D> ArrayBase<S, D>
/// as the element that would be indexed as `(N-1)q` if the lane were to be sorted
/// in increasing order.
/// If `(N-1)q` is not an integer the desired percentile lies between
/// two data points: we return the lower, nearest or higher datapoint depending
/// on `interpolation_strategy`.
/// two data points: we return the lower, nearest, higher or interpolated
/// value depending on the type `Interpolate` bound `I`.
///
/// Some examples:
/// - `q=0.` returns the minimum along each 1-dimensional lane;
Expand All @@ -214,7 +276,7 @@ impl<A, S, D> ArrayBase<S, D>
where D: RemoveAxis,
A: Ord + Clone + Zero,
S: DataMut,
I: Interpolate<Array<A, D::Smaller>>,
I: Interpolate<A>,
{
assert!((0. <= q) && (q <= 1.));
let mut lower = None;
Expand Down