package org.nd4j.examples;
import org.nd4j.linalg.api.ndarray.INDArray;
import org.nd4j.linalg.api.ops.CustomOp;
import org.nd4j.linalg.api.ops.DynamicCustomOp;
import org.nd4j.linalg.factory.Nd4j;
/**
*
* 定制操作是那些在C++ (libnd4j)中定义的，它们还没有被映射为具有Java便利方法，如1.0.0-beta版本。
* 最终，所有的操作都将被映射成具有Java便利性的方法。同时，可以使用下面显示的“DynamicCustomOp”方法访问它们
*
*/
public class CustomOpsExamples {
public static void main(String[] args){
//第一个示例：反转操作。此操作沿指定维度反转值。
//c++代码:https://github.com/deeplearning4j/libnd4j/blob/master/include/ops/declarable/generic/transforms/reverse.cpp#L15
//生成线性间隔向量,如下生成1-50，步长大小为50的标量
INDArray input = Nd4j.linspace(1, 50, 50)
//变形为5行10列的二维数组
.reshape(5,10);
//按输入形状创建一个输出数组
INDArray output = Nd4j.create(input.shape());
//反转操作
CustomOp op = DynamicCustomOp.builder("reverse")
.addInputs(input)
.addOutputs(output)
//沿维度0（行）进行反转
.addIntegerArguments(0)
.build();
//执行操作
Nd4j.getExecutioner().exec(op);
System.out.println("反转前");
System.out.println(input);
System.out.println();
System.out.println("反转后");
System.out.println(output);
//另一个例子：网格
//c++ 代码: https://github.com/deeplearning4j/libnd4j/blob/master/include/ops/declarable/generic/broadcastable/meshgrid.cpp
//创建[[ 0, 0.3333, 0.6667, 1.0000]]，即从0开始到1，生成4个数字，每个数字值=((1-0)/(4-1))n n=0,1,2,3
INDArray input1 = Nd4j.linspace(0, 1, 4);
//创建[[ 0, 0.2500, 0.5000, 0.7500, 1.0000]]，即从0开始到1，生成5个数字，每个数字值=((1-0)/(5-1))n n=0,1,2,3,4
INDArray input2 = Nd4j.linspace(0, 1, 5);
//创建5行4列的二维数组
INDArray output1 = Nd4j.create(5,4);
//创建5行4列的二维数组
INDArray output2 = Nd4j.create(5,4);
//meshgrid详情参考https://blog.csdn.net/u013346007/article/details/54581253
op = DynamicCustomOp.builder("meshgrid")
.addInputs(input1, input2)
.addOutputs(output1,output2)
.build();
Nd4j.getExecutioner().exec(op);
System.out.println("meshgrid前");
System.out.println(input1 + "\n\n" + input2);
System.out.println("meshgrid后");
//output1=input1列数*input2列数=4*5的矩阵，即用input1垂直堆叠n=input2列数 次
//output2=input2转置后水平堆叠n=input1列数 次
System.out.println(output1 + "\n\n"+output2);
}
}
运行结果
反转前
[[ 1.0000, 2.0000, 3.0000, 4.0000, 5.0000, 6.0000, 7.0000, 8.0000, 9.0000, 10.0000],
[ 11.0000, 12.0000, 13.0000, 14.0000, 15.0000, 16.0000, 17.0000, 18.0000, 19.0000, 20.0000],
[ 21.0000, 22.0000, 23.0000, 24.0000, 25.0000, 26.0000, 27.0000, 28.0000, 29.0000, 30.0000],
[ 31.0000, 32.0000, 33.0000, 34.0000, 35.0000, 36.0000, 37.0000, 38.0000, 39.0000, 40.0000],
[ 41.0000, 42.0000, 43.0000, 44.0000, 45.0000, 46.0000, 47.0000, 48.0000, 49.0000, 50.0000]]
反转后
[[ 10.0000, 9.0000, 8.0000, 7.0000, 6.0000, 5.0000, 4.0000, 3.0000, 2.0000, 1.0000],
[ 20.0000, 19.0000, 18.0000, 17.0000, 16.0000, 15.0000, 14.0000, 13.0000, 12.0000, 11.0000],
[ 30.0000, 29.0000, 28.0000, 27.0000, 26.0000, 25.0000, 24.0000, 23.0000, 22.0000, 21.0000],
[ 40.0000, 39.0000, 38.0000, 37.0000, 36.0000, 35.0000, 34.0000, 33.0000, 32.0000, 31.0000],
[ 50.0000, 49.0000, 48.0000, 47.0000, 46.0000, 45.0000, 44.0000, 43.0000, 42.0000, 41.0000]]
meshgrid前
[[ 0, 0.3333, 0.6667, 1.0000]]
[[ 0, 0.2500, 0.5000, 0.7500, 1.0000]]
meshgrid后
[[ 0, 0.3333, 0.6667, 1.0000],
[ 0, 0.3333, 0.6667, 1.0000],
[ 0, 0.3333, 0.6667, 1.0000],
[ 0, 0.3333, 0.6667, 1.0000],
[ 0, 0.3333, 0.6667, 1.0000]]
[[ 0, 0, 0, 0],
[ 0.2500, 0.2500, 0.2500, 0.2500],
[ 0.5000, 0.5000, 0.5000, 0.5000],
[ 0.7500, 0.7500, 0.7500, 0.7500],
[ 1.0000, 1.0000, 1.0000, 1.0000]]
翻译：风一样的男子
image