如何根据第一列中的选择来计算使用CSV中的项目？

import csv

def calculate_selected_projects(csv_file, selection):
    selected_projects = []
    
    with open(csv_file, 'r') as file:
        reader = csv.DictReader(file)
        
        for row in reader:
            if row['选择'] == selection:
                selected_projects.append(row)
    
    # 在这里进行所选项目的计算操作
    total_cost = sum(float(project['成本']) for project in selected_projects)
    
    return total_cost

# 示例用法
csv_file = 'projects.csv'
selection = 'A'
total_cost = calculate_selected_projects(csv_file, selection)
print(f"选择为'{selection}'的项目总成本为: {total_cost}")