Python 2.7:如何正确拆分CSV文件？

import csv

def split_csv_file(input_file, output_prefix, chunk_size):
    with open(input_file, 'r') as file:
        reader = csv.reader(file)
        header = next(reader)  # 获取CSV文件的头部

        chunk_count = 1
        current_chunk_size = 0
        current_chunk_rows = []
        for row in reader:
            current_chunk_rows.append(row)
            current_chunk_size += 1

            if current_chunk_size >= chunk_size:
                output_file = f"{output_prefix}_{chunk_count}.csv"
                with open(output_file, 'w') as output:
                    writer = csv.writer(output)
                    writer.writerow(header)
                    writer.writerows(current_chunk_rows)

                chunk_count += 1
                current_chunk_size = 0
                current_chunk_rows = []

        # 处理剩余的行
        if current_chunk_size > 0:
            output_file = f"{output_prefix}_{chunk_count}.csv"
            with open(output_file, 'w') as output:
                writer = csv.writer(output)
                writer.writerow(header)
                writer.writerows(current_chunk_rows)

# 示例用法
split_csv_file('input.csv', 'output', 1000)