コード

from mcap.reader import make_reader
from mcap_ros2.decoder import DecoderFactory
from tqdm import tqdm
import pandas as pd

mcap_file = "hoge.mcap"
target_status_name = "hoge_monitor: hoge_monitor"

statuses = []

with open(mcap_file, "rb") as f:
    reader = make_reader(f, decoder_factories=[DecoderFactory()])
    for schema, channel, message, ros_msg in tqdm(reader.iter_decoded_messages(), dynamic_ncols=True):
        if channel.topic != "/diagnostics":
            continue

        for status in ros_msg.status:
            if status.name == target_status_name:
                dic = {
                    "sec": ros_msg.header.stamp.sec,
                    "nanosec": ros_msg.header.stamp.nanosec,
                    "level": status.level,
                    "message": status.message,
                    "hardware_id": status.hardware_id
                }

                for value in status.values:
                    dic[value.key] = value.value
                
                statuses.append(dic)

df = pd.DataFrame(statuses)
実行結果
