如何用Python编写自动化脚本实现PI传感器数据采集、存储与分析？

Absolutely! Both of your goals—automating your sensor script to run on a schedule and saving data for later analysis—are totally doable with Python on a Raspberry Pi. Let’s walk through each part with practical, actionable examples.

1. Automating Script Execution (Scheduled Runs) #

You’ve got two solid options here, depending on how robust you need the setup to be:

Option 1: Simple Python Loop with time.sleep() #

Great for quick testing or short-term use. Just wrap your existing sensor logic in a loop that pauses for your desired interval between runs.

import time
# Assume your existing sensor reading function is here
def get_sensor_data():
    # Replace with your actual sensor code to fetch temp, pressure, altitude
    temperature = 22.5
    pressure = 1013.25
    altitude = 120.0
    return temperature, pressure, altitude

# Set your desired interval in seconds (e.g., 300 = 5 minutes)
INTERVAL = 300

while True:
    temp, press, alt = get_sensor_data()
    print(f"Temp: {temp}°C, Pressure: {press} hPa, Altitude: {alt}m")
    # We'll add data saving logic here next
    time.sleep(INTERVAL)

Pro tip: If you want this to run in the background even when you close your terminal, launch it with nohup python3 code.py &—the & sends it to the background, and nohup keeps it running after you log out.

Option 2: System Cron Job (More Reliable for Long-Term Use) #

Cron is Linux’s built-in scheduler—it’s stable, will restart your script if your Pi reboots, and doesn’t require keeping a Python loop running. Here’s how to set it up:

1. Open your user’s crontab editor:

   crontab -e
   

2. Add a line at the end to schedule your script. For example, to run every 5 minutes:

   */5 * * * * /usr/bin/python3 /home/pi/code.py >> /home/pi/sensor_logs.log 2>&1
   

   Let’s break this down:
   • */5 * * * *: Runs every 5 minutes (adjust the first number to change intervals—e.g., 0 */1 * * * for hourly)
   • /usr/bin/python3: Absolute path to your Python interpreter (find yours with which python3)
   • /home/pi/code.py: Absolute path to your script
   • >> /home/pi/sensor_logs.log 2>&1: Saves output/errors to a log file (optional but super helpful for debugging)
3. Save and exit—cron will automatically apply the new schedule.

2. Saving Data for Analysis #

CSV (Comma-Separated Values) is the ideal format here—it’s human-readable, works with Excel/Google Sheets, and integrates seamlessly with Python tools like pandas for advanced analysis. Here’s how to add this to your script:

Option 1: Using Python’s Built-in csv Module (No Extra Installs) #

This is lightweight and doesn’t require any external packages:

import time
import csv
from datetime import datetime

def get_sensor_data():
    # Replace with your actual sensor code
    temperature = 22.5
    pressure = 1013.25
    altitude = 120.0
    return temperature, pressure, altitude

INTERVAL = 300
DATA_FILE = "/home/pi/sensor_data.csv"

def save_data(temp, press, alt):
    # Add timestamp for context (critical for analysis)
    timestamp = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
    # Check if file exists to write header only once
    file_exists = False
    try:
        with open(DATA_FILE, 'r') as f:
            file_exists = True
    except FileNotFoundError:
        pass

    # Write data to CSV
    with open(DATA_FILE, 'a', newline='') as f:
        writer = csv.writer(f)
        if not file_exists:
            # Write header row
            writer.writerow(["Timestamp", "Temperature (°C)", "Pressure (hPa)", "Altitude (m)"])
        # Write the latest sensor reading
        writer.writerow([timestamp, temp, press, alt])

# Main loop
while True:
    temp, press, alt = get_sensor_data()
    save_data(temp, press, alt)
    print(f"Saved data: {temp}°C, {press}hPa, {alt}m at {datetime.now().strftime('%Y-%m-%d %H:%M:%S')}")
    time.sleep(INTERVAL)

Option 2: Using pandas (For Easier Advanced Analysis) #

If you plan to do things like plot trends, filter data by date, or calculate averages later, pandas simplifies this work. First install it:

pip install pandas

Then modify your save function:

import pandas as pd
from datetime import datetime

def save_data(temp, press, alt):
    timestamp = datetime.now()
    # Create a small DataFrame with the new reading
    new_data = pd.DataFrame({
        "Timestamp": [timestamp],
        "Temperature (°C)": [temp],
        "Pressure (hPa)": [press],
        "Altitude (m)": [alt]
    })
    # Append to CSV (automatically creates file if it doesn't exist)
    new_data.to_csv(DATA_FILE, mode='a', header=not pd.io.common.file_exists(DATA_FILE), index=False)

Quick Final Checks #

• Ensure your script has execute permissions: chmod +x /home/pi/code.py
• If using cron, double-check all absolute paths—cron uses a minimal environment, so relative paths might break your script.
• For sensor access (e.g., I2C sensors), make sure your Pi user is in the correct group: sudo usermod -aG i2c pi

内容的提问来源于stack exchange，提问作者Pras4