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Merge pull request #898 from SparrowLii/co_broadcast
Implement co-broadcasting in operator overloading
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use crate::error::*; | ||
use crate::{Dimension, Ix0, Ix1, Ix2, Ix3, Ix4, Ix5, Ix6, IxDyn}; | ||
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/// Calculate the common shape for a pair of array shapes, that they can be broadcasted | ||
/// to. Return an error if the shapes are not compatible. | ||
/// | ||
/// Uses the [NumPy broadcasting rules] | ||
// (https://docs.scipy.org/doc/numpy/user/basics.broadcasting.html#general-broadcasting-rules). | ||
pub(crate) fn co_broadcast<D1, D2, Output>(shape1: &D1, shape2: &D2) -> Result<Output, ShapeError> | ||
where | ||
D1: Dimension, | ||
D2: Dimension, | ||
Output: Dimension, | ||
{ | ||
let (k, overflow) = shape1.ndim().overflowing_sub(shape2.ndim()); | ||
// Swap the order if d2 is longer. | ||
if overflow { | ||
return co_broadcast::<D2, D1, Output>(shape2, shape1); | ||
} | ||
// The output should be the same length as shape1. | ||
let mut out = Output::zeros(shape1.ndim()); | ||
for (out, s) in izip!(out.slice_mut(), shape1.slice()) { | ||
*out = *s; | ||
} | ||
for (out, s2) in izip!(&mut out.slice_mut()[k..], shape2.slice()) { | ||
if *out != *s2 { | ||
if *out == 1 { | ||
*out = *s2 | ||
} else if *s2 != 1 { | ||
return Err(from_kind(ErrorKind::IncompatibleShape)); | ||
} | ||
} | ||
} | ||
Ok(out) | ||
} | ||
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pub trait DimMax<Other: Dimension> { | ||
/// The resulting dimension type after broadcasting. | ||
type Output: Dimension; | ||
} | ||
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/// Dimensions of the same type remain unchanged when co_broadcast. | ||
/// So you can directly use D as the resulting type. | ||
/// (Instead of <D as DimMax<D>>::BroadcastOutput) | ||
impl<D: Dimension> DimMax<D> for D { | ||
type Output = D; | ||
} | ||
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macro_rules! impl_broadcast_distinct_fixed { | ||
($smaller:ty, $larger:ty) => { | ||
impl DimMax<$larger> for $smaller { | ||
type Output = $larger; | ||
} | ||
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impl DimMax<$smaller> for $larger { | ||
type Output = $larger; | ||
} | ||
}; | ||
} | ||
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impl_broadcast_distinct_fixed!(Ix0, Ix1); | ||
impl_broadcast_distinct_fixed!(Ix0, Ix2); | ||
impl_broadcast_distinct_fixed!(Ix0, Ix3); | ||
impl_broadcast_distinct_fixed!(Ix0, Ix4); | ||
impl_broadcast_distinct_fixed!(Ix0, Ix5); | ||
impl_broadcast_distinct_fixed!(Ix0, Ix6); | ||
impl_broadcast_distinct_fixed!(Ix1, Ix2); | ||
impl_broadcast_distinct_fixed!(Ix1, Ix3); | ||
impl_broadcast_distinct_fixed!(Ix1, Ix4); | ||
impl_broadcast_distinct_fixed!(Ix1, Ix5); | ||
impl_broadcast_distinct_fixed!(Ix1, Ix6); | ||
impl_broadcast_distinct_fixed!(Ix2, Ix3); | ||
impl_broadcast_distinct_fixed!(Ix2, Ix4); | ||
impl_broadcast_distinct_fixed!(Ix2, Ix5); | ||
impl_broadcast_distinct_fixed!(Ix2, Ix6); | ||
impl_broadcast_distinct_fixed!(Ix3, Ix4); | ||
impl_broadcast_distinct_fixed!(Ix3, Ix5); | ||
impl_broadcast_distinct_fixed!(Ix3, Ix6); | ||
impl_broadcast_distinct_fixed!(Ix4, Ix5); | ||
impl_broadcast_distinct_fixed!(Ix4, Ix6); | ||
impl_broadcast_distinct_fixed!(Ix5, Ix6); | ||
impl_broadcast_distinct_fixed!(Ix0, IxDyn); | ||
impl_broadcast_distinct_fixed!(Ix1, IxDyn); | ||
impl_broadcast_distinct_fixed!(Ix2, IxDyn); | ||
impl_broadcast_distinct_fixed!(Ix3, IxDyn); | ||
impl_broadcast_distinct_fixed!(Ix4, IxDyn); | ||
impl_broadcast_distinct_fixed!(Ix5, IxDyn); | ||
impl_broadcast_distinct_fixed!(Ix6, IxDyn); | ||
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#[cfg(test)] | ||
#[cfg(feature = "std")] | ||
mod tests { | ||
use super::co_broadcast; | ||
use crate::{Dimension, Dim, DimMax, ShapeError, Ix0, IxDynImpl, ErrorKind}; | ||
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#[test] | ||
fn test_broadcast_shape() { | ||
fn test_co<D1, D2>( | ||
d1: &D1, | ||
d2: &D2, | ||
r: Result<<D1 as DimMax<D2>>::Output, ShapeError>, | ||
) where | ||
D1: Dimension + DimMax<D2>, | ||
D2: Dimension, | ||
{ | ||
let d = co_broadcast::<D1, D2, <D1 as DimMax<D2>>::Output>(&d1, d2); | ||
assert_eq!(d, r); | ||
} | ||
test_co(&Dim([2, 3]), &Dim([4, 1, 3]), Ok(Dim([4, 2, 3]))); | ||
test_co( | ||
&Dim([1, 2, 2]), | ||
&Dim([1, 3, 4]), | ||
Err(ShapeError::from_kind(ErrorKind::IncompatibleShape)), | ||
); | ||
test_co(&Dim([3, 4, 5]), &Ix0(), Ok(Dim([3, 4, 5]))); | ||
let v = vec![1, 2, 3, 4, 5, 6, 7]; | ||
test_co( | ||
&Dim(vec![1, 1, 3, 1, 5, 1, 7]), | ||
&Dim([2, 1, 4, 1, 6, 1]), | ||
Ok(Dim(IxDynImpl::from(v.as_slice()))), | ||
); | ||
let d = Dim([1, 2, 1, 3]); | ||
test_co(&d, &d, Ok(d)); | ||
test_co( | ||
&Dim([2, 1, 2]).into_dyn(), | ||
&Dim(0), | ||
Err(ShapeError::from_kind(ErrorKind::IncompatibleShape)), | ||
); | ||
test_co( | ||
&Dim([2, 1, 1]), | ||
&Dim([0, 0, 1, 3, 4]), | ||
Ok(Dim([0, 0, 2, 3, 4])), | ||
); | ||
test_co(&Dim([0]), &Dim([0, 0, 0]), Ok(Dim([0, 0, 0]))); | ||
test_co(&Dim(1), &Dim([1, 0, 0]), Ok(Dim([1, 0, 0]))); | ||
test_co( | ||
&Dim([1, 3, 0, 1, 1]), | ||
&Dim([1, 2, 3, 1]), | ||
Err(ShapeError::from_kind(ErrorKind::IncompatibleShape)), | ||
); | ||
} | ||
} |
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