如何修改Python代码实现Excel列从A迭代到ZZ？

原代码的问题在于仅使用string.ascii_uppercase遍历单个大写字母（A-Z），无法覆盖AA到ZZ的双字母列标识。以下是两种可行的修改方案：

方法一：根据工作表实际列数动态生成（推荐） #

利用openpyxl.utils中的get_column_letter函数，将列号转换为对应的字母标识（1→A，27→AA，702→ZZ），遍历工作表的所有实际列，既灵活又避免无效遍历：

import pandas
from openpyxl import load_workbook
from openpyxl.utils import get_column_letter

book = load_workbook('QualityReview Business-Template.xlsx')

writer = pandas.ExcelWriter('QualityReview Business-Template.xlsx', engine='openpyxl') 
writer.book = book
busi_issue_date.to_excel(writer, "IssueData")
worksheet = book["IssueData"]

# 遍历所有实际列，生成对应字母标识
for col_num in range(1, worksheet.max_column + 1):
    letter = get_column_letter(col_num)
    max_width = 0

    for row_number in range(1, worksheet.max_row + 1):
        cell_value = str(worksheet[f'{letter}{row_number}'].value)
        if len(cell_value) > max_width:
            max_width = len(cell_value)
    # 统一设置列宽，避免重复赋值提升效率
    worksheet.column_dimensions[letter].width = max_width + 1

writer.save()

优化说明：将列宽赋值移到内层循环之外，避免每一行都重复设置，提升代码效率。

方法二：手动生成A到ZZ的所有列标识 #

如果需要固定遍历A到ZZ的所有列（不管工作表实际列数），可以通过生成单字母+双字母组合实现：

import pandas
from openpyxl import load_workbook
from openpyxl.utils import get_column_letter
from string import ascii_uppercase
import itertools

book = load_workbook('QualityReview Business-Template.xlsx')

writer = pandas.ExcelWriter('QualityReview Business-Template.xlsx', engine='openpyxl') 
writer.book = book
busi_issue_date.to_excel(writer, "IssueData")
worksheet = book["IssueData"]

# 生成A-Z + AA-ZZ的所有列标识
cols = list(ascii_uppercase) + [''.join(pair) for pair in itertools.product(ascii_uppercase, repeat=2)]

for letter in cols:
    max_width = 0
    # 仅处理工作表中存在的列，避免索引错误
    if letter not in worksheet.column_dimensions:
        continue
    for row_number in range(1, worksheet.max_row + 1):
        cell_value = str(worksheet[f'{letter}{row_number}'].value)
        if len(cell_value) > max_width:
            max_width = len(cell_value)
    worksheet.column_dimensions[letter].width = max_width + 1

writer.save()

注意：添加了列存在性判断，避免遍历到工作表中不存在的列时抛出错误。

内容的提问来源于stack exchange，提问作者user3044949