改进该脚本，在txt文件每次输出的开头增加一个数据，该数据是对应话题第一次消息发布时的时间戳

为了改进脚本，在每个txt文件开始添加对应主题第一次消息发布的数据，你需要在初始化文件写入之前，存储并检查每个主题第一次接收到的数据的时间戳。以下是更新后的代码：

import rospy
from nav_msgs.msg import Odometry
from rospy.rostime import Time
from datetime import datetime

# 存储首次接收到的数据时间戳
first_timestamps = {
    '/Odometry_left': None,
    '/Odometry': None,
}

def get_first_timestamp(topic_name):
    if topic_name not in first_timestamps or first_timestamps[topic_name] is None:
        return "First message time unavailable for " + topic_name
    else:
        return str(first_timestamps[topic_name])

def robot0_callback(data):
    global first_timestamps
    if first_timestamps.get('/Odometry_left', None) is None:
        first_timestamps['/Odometry_left'] = data.header.stamp.to_sec()
        
    pose = data.pose.pose
    timestamp = data.header.stamp.to_sec()
    x = pose.position.x
    y = pose.position.y
    z = pose.position.z
    px = pose.orientation.x
    py = pose.orientation.y
    pz = pose.orientation.z
    pw = pose.orientation.w

    with open('1.txt', 'a', newline='') as f:
        # 在每一行开始写入数据前先写入首次时间戳
        f.write(get_first_timestamp('/Odometry_left'))
        f.write(" " * (len(str(timestamp)) + 1))  # 确保时间对齐
        line = f"{timestamp} {x} {y} {z} {px} {py} {pz} {pw}\n"
        f.write(line)

def robot1_callback(data):
    global first_timestamps
    if first_timestamps.get('/Odometry', None) is None:
        first_timestamps['/Odometry'] = data.header.stamp.to_sec()

    pose = data.pose.pose
    timestamp = data.header.stamp.to_sec()
    x = pose.position.x
    y = pose.position.y
    z = pose.position.z
    px = pose.orientation.x
    py = pose.orientation.y
    pz = pose.orientation.z
    pw = pose.orientation.w

    with open('2.txt', 'a', newline='') as f:
        f.write(get_first_timestamp('/Odometry'))
        f.write(" " * (len(str(timestamp)) + 1))
        line = f"{timestamp} {x} {y} {z} {px} {py} {pz} {pw}\n"
        f.write(line)
        
# ...其他代码保持不变...

现在，当你运行此版本的脚本，每个txt文件都会首先包含各自主题首次接收到的消息时间戳，随后才是后续接收到的数据。