问题描述
我正在尝试使用自定义值修改现有Arrayfire矩阵中的值。下面是将几行和几列更改为指定值(1.0)的示例。但是,我却努力不做两件事:
- 改为更改要更改区域的尺寸(3x3)->(2x2)。
- 水平或垂直移动要更改的区域。我所做的任何更改似乎都给出了无效的索引错误。
use arrayfire::{constant,Dim4,Seq,assign_seq,print};
let a = constant(2.0 as f32,Dim4::new(&[5,3,1,1]));
let b = constant(1.0 as f32,Dim4::new(&[3,1]));
let seqs = &[Seq::new(1.0,3.0,1.0),Seq::default()];
print(&a);
// 2.0 2.0 2.0
// 2.0 2.0 2.0
// 2.0 2.0 2.0
// 2.0 2.0 2.0
// 2.0 2.0 2.0
let sub = assign_seq(&a,seqs,&b);
print(&sub);
// 2.0 2.0 2.0
// 1.0 1.0 1.0
// 1.0 1.0 1.0
// 1.0 1.0 1.0
// 2.0 2.0 2.0
解决方法
经过几天的研究,我与图书馆作者联系后找到了答案:
use arrayfire::{constant,Dim4,Seq,assign_seq,print};
//This is the "parent" matrix.
let a = constant(2.0 as f32,Dim4::new(&[4,4,1,1]));
//To modify a 2x2 area inside a,this must be 2x2 as well
let b = constant(1.0 as f32,Dim4::new(&[2,2,1]));
//Use two seq::new objects,NOTE that matrices are column major.
let seqs = &[Seq::new(1.0,1.0,1.0),Seq::new(1.0,1.0)];
Arrayfire 3.7.1还引入了一种新的优雅语法:
let mut a = arrayfire::constant(2.0 as f32,arrayfire::dim4!(4,4));
let b = arrayfire::constant(1.0 as f32,arrayfire::dim4!(2,2));
arrayfire::print(&a);
arrayfire::eval!(a[1:1:1,1:1:1] = b);
arrayfire::print(&a);