test_data.targets

`test_data.targets`是一个PyTorch数据集对象中的属性，用于访问该数据集的标签。在PyTorch中，数据集通常由数据和标签组成，其中数据是一个张量，标签是一个整数或一个张量。

`test_data.targets`属性是一个张量，它包含了测试数据集的所有标签。在PyTorch中，标签通常是一个整数，它表示该数据点所属的类别。例如，在MNIST数据集中，每个数据点都是一个手写数字图像，标签是一个表示该数字的整数，范围从0到9。

以下是一个简单的示例，演示了如何访问数据集的标签：

import torch
import torchvision

test_data = torchvision.datasets.MNIST(root='./data', train=False, download=True)
print(test_data.targets)

在这个示例中，我们使用PyTorch的`torchvision.datasets.MNIST`数据集对象创建了一个测试数据集。然后，我们使用`test_data.targets`属性访问测试数据集的标签，并将其打印出来。

相关问题

test_y = test_data.targets[:500].numpy()

这看起来像是在将 PyTorch 的 Tensor 类型转换为 NumPy 数组类型。可以推断出 `test_data` 是一个 PyTorch 的数据集对象，其中包含了测试数据和测试标签，而 `test_data.targets` 则是测试数据对应的标签。这里的代码将前 500 个测试数据的标签取出来，并将其转换为 NumPy 数组类型，存储在变量 `test_y` 中。

在ros项目中添加发送websocket wss消息的功能，修改如下代码并在CmakeLists.txt中添加依赖，实现将serialized_data发送到wss://autopilot-test.t3go.cn:443/api/v1/vehicle/push/message/LFB1FV696M2L43840。main.cpp：#include "ros/ros.h" #include "std_msgs/String.h" #include <boost/thread/locks.hpp> #include <boost/thread/shared_mutex.hpp> #include "third_party/apollo/proto/perception/perception_obstacle.pb.h" #include "t3_perception.pb.h" apollo::perception::PerceptionObstacles perception_obstacles_; void perceptionCallback(const std_msgs::String& msg) { ROS_WARN("t3 perceptionCallback parse"); if (perception_obstacles_.ParseFromString(msg.data)) { double timestamp = perception_obstacles_.header().timestamp_sec(); ROS_INFO("t3 perceptionCallback timestamp %f count:%d", timestamp, perception_obstacles_.perception_obstacle().size()); std::string data; perception_obstacles_.SerializeToString(&data); VehData veh_data; veh_data.set_messagetype(5); veh_data.set_messagedes("PerceptionObstacles"); veh_data.set_contents(data); std::string serialized_data; veh_data.SerializeToString(&serialized_data); } else { ROS_ERROR("t3 perceptionCallback parse fail!"); } } int main(int argc, char **argv) { ros::init(argc, argv, "listener"); ros::NodeHandle n; ros::Subscriber sub = n.subscribe("/perception_node/perception_objects", 1000, perceptionCallback); ros::spin(); return 0; }CMakeLists.txt：cmake_minimum_required(VERSION 3.0.2) project(t3) find_package(catkin REQUIRED COMPONENTS roscpp rospy pcl_ros std_msgs third_party ) find_package(Protobuf REQUIRED) include_directories(${Protobuf_INCLUDE_DIRS} ${CMAKE_CURRENT_BINARY_DIR}/..) find_package(Boost REQUIRED) include_directories(${Boost_INCLUDE_DIRS}) set(ixwebsocket_INCLUDE_DIR "/usr/local/include/ixwebsocket") set(ixwebsocket_LIBRARIES "/usr/local/lib/libixwebsocket.a") include_directories(${ixwebsocket_INCLUDE_DIR}) include_directories(${CATKIN_DEVEL_PREFIX}/${CATKIN_GLOBAL_INCLUDE_DESTINATION}/${PROJECT_NAME}) include_directories(${CATKIN_DEVEL_PREFIX}/${CATKIN_GLOBAL_INCLUDE_DESTINATION}/smartview) catkin_package(INCLUDE_DIRS ${PROJECT_INCLUDE_DIRS} DEPENDS ${GFLAGS_LIBRARIES} ) include_directories( ${catkin_INCLUDE_DIRS} ${PROTOBUF_INCLUDE_DIR} ${PROJECT_SOURCE_DIR}/.. ) add_executable(${PROJECT_NAME}_node src/main.cpp ) add_dependencies(${PROJECT_NAME}_node ${catkin_EXPORTED_TARGETS}) target_link_libraries(${PROJECT_NAME}_node ${catkin_LIBRARIES} ${PROTOBUF_LIBRARIES} smartview_proto ) install(TARGETS ${PROJECT_NAME}_node ARCHIVE DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION} LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION} RUNTIME DESTINATION ${CATKIN_GLOBAL_BIN_DESTINATION} )

你可以使用以下代码来添加发送websocket wss消息的功能，同时在CmakeLists.txt中添加依赖：

#include "ros/ros.h"
#include "std_msgs/String.h"
#include <boost/thread/locks.hpp>
#include <boost/thread/shared_mutex.hpp>
#include "third_party/apollo/proto/perception/perception_obstacle.pb.h"
#include "t3_perception.pb.h"

#include <ixwebsocket/IXWebSocket.h>

using namespace ix;

apollo::perception::PerceptionObstacles perception_obstacles_;

void perceptionCallback(const std_msgs::String& msg) {
    ROS_WARN("t3 perceptionCallback parse");

    if (perception_obstacles_.ParseFromString(msg.data)) {
        double timestamp = perception_obstacles_.header().timestamp_sec();
        ROS_INFO("t3 perceptionCallback timestamp %f count:%d", timestamp, perception_obstacles_.perception_obstacle().size());
        std::string data;
        perception_obstacles_.SerializeToString(&data);
        VehData veh_data;
        veh_data.set_messagetype(5);
        veh_data.set_messagedes("PerceptionObstacles");
        veh_data.set_contents(data);
        std::string serialized_data;
        veh_data.SerializeToString(&serialized_data);

        // create a WebSocket connection
        WebSocket websocket;
        websocket.setTLSOptions({}); // use default options

        websocket.setOnMessageCallback([](const WebSocketMessagePtr& msg) {
            std::cout << "Received message: " << msg->str << std::endl;
        });

        websocket.setOnCloseCallback([](WebSocket& ws, const WebSocketCloseInfo& info) {
            std::cout << "WebSocket closed: " << info.reason << std::endl;
        });

        websocket.setOnErrorCallback([](const std::error_code& ec) {
            std::cout << "Error: " << ec << ", error message: " << ec.message() << std::endl;
        });

        websocket.connect("wss://autopilot-test.t3go.cn:443/api/v1/vehicle/push/message/LFB1FV696M2L43840");
        websocket.send(serialized_data);
        websocket.close();
    } else {
        ROS_ERROR("t3 perceptionCallback parse fail!");
    }
}

int main(int argc, char **argv) {
    ros::init(argc, argv, "listener");
    ros::NodeHandle n;
    ros::Subscriber sub = n.subscribe("/perception_node/perception_objects", 1000, perceptionCallback);
    ros::spin();
    return 0;
}

在CmakeLists.txt中添加以下依赖：

find_package(ixwebsocket REQUIRED)
target_link_libraries(${PROJECT_NAME}_node ixwebsocket)

注意，你需要安装ixwebsocket库以使用WebSocket功能。