c++ - “成员的无效使用……你忘了&吗?” 访问另一个类对象中的类对象
问题描述
我正在尝试编写自己的 NeuralNetwork,并使用自己的 Matrix2D 类进行操作。我正在尝试写出神经网络第一个权重矩阵的值,但出现如下错误: 161|error: invalid use of member 'Matrix2D NeuralNewtork::first_hidden_weights()' (你忘记了 '&' 吗?) |
#include <iostream>
#include <stdlib.h>
#include <time.h>
using namespace std;
float RandomNumber()
{
return ((((double) rand() / (RAND_MAX))*2)-1);
}
class Matrix2D{
public:
int rows;
int columns;
float **matrix;
Matrix2D(int x, int y){
rows = x;
columns = y;
matrix = new float*[rows];
for (int i = 0; i < rows; i++) {
matrix[i] = new float[columns];
}
for (int i = 0; i < rows; i++) {
for (int j = 0; j < columns; j++) {
matrix[i][j] = 0;
}
}
}
Matrix2D randomizeMatrix(){
Matrix2D result(rows, columns);
for (int i = 0; i < rows; i++) {
for (int j = 0; j < columns; j++) {
matrix[i][j] = RandomNumber();
}
}
return result;
}
static Matrix2D scalarMultiply(Matrix2D x, float y){
Matrix2D result(x.rows, x.columns);
for (int i = 0; i < x.rows; i++) {
for (int j = 0; j < x.columns; j++) {
result.matrix[i][j] = x.matrix[i][j] * y;
}
}
return result;
}
static Matrix2D scalarAddition(Matrix2D x, float y){
Matrix2D result(x.rows, x.columns);
for (int i = 0; i < x.rows; i++) {
for (int j = 0; j < x.columns; j++) {
result.matrix[i][j] = x.matrix[i][j] + y;
}
}
return result;
}
static Matrix2D scalarSubstraction(Matrix2D x, float y){
Matrix2D result(x.rows, x.columns);
for (int i = 0; i < x.rows; i++) {
for (int j = 0; j < x.columns; j++) {
result.matrix[i][j] = x.matrix[i][j] - y;
}
}
return result;
}
static Matrix2D matrixAddition(Matrix2D x, Matrix2D y){
Matrix2D result(x.rows, x.columns);
for (int i = 0; i < x.rows; i++) {
for (int j = 0; j < x.columns; j++) {
result.matrix[i][j] = x.matrix[i][j] + y.matrix[i][j];
}
}
return result;
}
static Matrix2D matrixTranspose(Matrix2D x){
Matrix2D result(x.columns, x.rows);
for (int i = 0; i < x.rows; i++) {
for (int j = 0; j < x.columns; j++) {
result.matrix[j][i] = x.matrix[i][j];
}
}
return result;
}
static Matrix2D matrixMultiplication(Matrix2D x, Matrix2D y){
Matrix2D result(x.rows, y.columns);
for (int i = 0; i < result.rows; i++) {
for (int j = 0; j < result.columns; j++) {
float sum = 0;
for (int k = 0; k < x.columns; i++) {
sum += x.matrix[i][k] * y.matrix[k][j];
}
result.matrix[i][j] = sum;
}
}
return result;
}
void printMatrix(){
for (int i = 0; i < rows; i++) {
for (int j = 0; j < columns; j++) {
cout << matrix[i][j] << " ";
}
cout << endl;
}
cout << endl;
}
};
class NeuralNewtork{
public:
int numberof_input_nodes;
int numberof_hidden_layers;
int numberof_hidden_nodes;
int numberof_output_nodes;
Matrix2D first_hidden_weights();
Matrix2D* hidden_weigths();
Matrix2D output_weights();
Matrix2D* hidden_biases();
Matrix2D output_biases();
NeuralNewtork(int input_nodes, int hidden_layers, int hidden_nodes, int output_nodes){
numberof_input_nodes = input_nodes;
numberof_hidden_layers = hidden_layers;
numberof_hidden_nodes = hidden_nodes;
numberof_output_nodes = output_nodes;
Matrix2D first_hidden_weights(hidden_nodes, input_nodes);
first_hidden_weights.randomizeMatrix();
Matrix2D* hidden_weigths[numberof_hidden_layers-1];
for (int i=0; i<numberof_hidden_layers-1; i++){
hidden_weigths[i] = new Matrix2D(numberof_hidden_nodes, numberof_hidden_nodes);
hidden_weigths[i]->randomizeMatrix();
}
Matrix2D output_weights(numberof_output_nodes, numberof_hidden_nodes);
output_weights.randomizeMatrix();
Matrix2D* hidden_biases[numberof_hidden_layers];
for (int i=0; i<numberof_hidden_layers; i++){
hidden_biases[i] = new Matrix2D(numberof_hidden_nodes, 1);
hidden_biases[i]->randomizeMatrix();
}
Matrix2D output_biases(numberof_output_nodes, 1);
output_biases.randomizeMatrix();
}
Matrix2D feedForward(Matrix2D input){
}
};
int main()
{
srand (time(0));
//Matrix2D myMatrix(3,7);
//myMatrix.randomizeMatrix();
//myMatrix.printMatrix();
NeuralNewtork nn(4, 3, 5, 1);
nn.first_hidden_weights.printMatrix(); //<=This line gives the error:
return 0;
}
我正在尝试打印 first_hidden_weight Matrix2D obejcts 矩阵组件,以查看我的代码是否按预期方式工作,但是当我尝试访问该变量时出现错误。
解决方案
第一个问题是您将所有权重定义为返回 Matrix2D 而不是成员变量的零参数函数。放下()
.
其次,您的构造函数创建并初始化影子变量,这些变量与您的成员变量完全解耦。使用=
运算符显式初始化它们:
first_hidden_weights = Matrix2D(hidden_nodes, input_nodes);
对于hidden_weights
andhidden_biases
成员,我建议你使用std::vector<Matrix2D>
. 这使内存管理自动化,并为您提供了许多方便的方法。hidden_weights
您可能会像这样初始化:
hidden_weights.reserve(numberof_hidden_layers-1);
for (int i=0; i<numberof_hidden_layers-1; i++){
hidden_weights.push_back(Matrix2D(numberof_hidden_nodes, numberof_hidden_nodes)); // or use emplace_back
hidden_weights.back().randomizeMatrix();
}
最后,由于您似乎randomizeMatrix
在构造后调用了很多,请考虑创建一个自动随机化的显式构造函数:
enum class Randomize { Randomize };
class Matrix2D {
...
Matrix2D(int x, int y, Randomize)
: Matrix2D(x, y) { // delegate to the simple constructor
randomizeMatrix();
}
...
};
然后,您可以简单地编写类似Matrix2D(x, y, Randomize)
.
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