Python写入CSV文件教程：csv模块与pandas两种写法

用Python把数据写入CSV文件，分别给出标准库csv和pandas to_csv两种写法，支持中文表头、追加模式、自定义分隔符，附完整代码。

场景痛点

处理完数据要导出给同事、传给系统、做报表，结果手动复制粘贴到Excel里，格式容易串、换行错位、中文乱码。用Python直接写CSV，一次成型，格式稳定，下次改个路径就能复用。

用到的库

pip install pandas

完整代码

# 用Python写入CSV文件
import csv
import pandas as pd

def write_with_csv_module(file_path):
"""用标准库csv.writer写入，适合一行一行追加、数据量不大的场景。"""
headers = ["姓名", "年龄", "城市", "月薪"]
data = [
["张三", 28, "北京", 18000],
["李四", 32, "上海", 22000],
["王五", 26, "深圳", 15000],
["赵六", 35, "杭州", 25000],
]

# newline="" 防止Windows写出空行
# encoding="utf-8-sig" 让Excel双击打开不乱码
with open(file_path, "w", newline="", encoding="utf-8-sig") as f:
writer = csv.writer(f)
writer.writerow(headers)      # 写表头
writer.writerows(data)        # 批量写多行
print(f"csv模块写入完成：{file_path}")

def append_row(file_path, new_row):
"""追加一行到已有CSV末尾。"""
with open(file_path, "a", newline="", encoding="utf-8-sig") as f:
writer = csv.writer(f)
writer.writerow(new_row)
print(f"已追加一行：{new_row}")

def write_with_pandas(file_path):
"""用pandas写入，适合已经是DataFrame的数据。"""
df = pd.DataFrame({
"姓名": ["孙七", "周八"],
"年龄": [29, 41],
"城市": ["广州", "成都"],
"月薪": [19000, 21000],
})
# index=False 不写pandas自带的行号列
df.to_csv(file_path, index=False, encoding="utf-8-sig")
print(f"pandas写入完成：{file_path}")

def main():
out1 = "output_csv_module.csv"
out2 = "output_pandas.csv"

write_with_csv_module(out1)
append_row(out1, ["吴九", 30, "南京", 17000])

write_with_pandas(out2)

if __name__ == "__main__":
main()