import csv

# 要保存的数据
data = [
    ['姓名', '年龄', '城市'],
    ['张三', 25, '北京'],
    ['李四', 30, '上海'],
    ['王五', 28, '广州']
]

# 写入CSV文件
with open('output.csv', 'w', newline='', encoding='utf-8') as f:
    writer = csv.writer(f)
    writer.writerows(data)

import csv

# 字典形式的数据
data = [
    {'name': '张三', 'age': 25, 'city': '北京'},
    {'name': '李四', 'age': 30, 'city': '上海'},
    {'name': '王五', 'age': 28, 'city': '广州'}
]

# 写入CSV文件
with open('output_dict.csv', 'w', newline='', encoding='utf-8') as f:
    fieldnames = ['name', 'age', 'city']  # 定义表头
    writer = csv.DictWriter(f, fieldnames=fieldnames)
    
    writer.writeheader()  # 写入表头
    writer.writerows(data)  # 写入数据

import csv

# 新数据
new_data = [
    ['赵六', 35, '深圳'],
    ['钱七', 40, '杭州']
]

# 追加模式('a')打开文件
with open('output.csv', 'a', newline='', encoding='utf-8') as f:
    writer = csv.writer(f)
    writer.writerows(new_data)

with open('output.csv', 'w', newline='', encoding='utf-8-sig') as f:
    # utf-8-sig 可以解决Excel打开时的乱码问题

# 使用不同的分隔符
with open('output.csv', 'w', newline='', encoding='utf-8') as f:
    writer = csv.writer(f, delimiter='|')  # 使用 | 作为分隔符
    writer.writerows(data)

# 分批写入大数据
batch_size = 1000
for i in range(0, len(big_data), batch_size):
    batch = big_data[i:i+batch_size]
    with open('big_output.csv', 'a', newline='', encoding='utf-8') as f:
        writer = csv.writer(f)
        writer.writerows(batch)

import csv

class CustomDialect(csv.Dialect):
    delimiter = ';'
    quotechar = '"'
    quoting = csv.QUOTE_MINIMAL
    lineterminator = '\n'

with open('custom.csv', 'w', newline='', encoding='utf-8') as f:
    writer = csv.writer(f, dialect=CustomDialect())
    writer.writerows(data)

import pandas as pd

# 创建DataFrame
df = pd.DataFrame(data, columns=['name', 'age', 'city'])

# 写入CSV
df.to_csv('pandas_output.csv', index=False, encoding='utf-8-sig')