意外收到 KeyError答案

【问题标题】：KeyError received when it is never expected意外收到 KeyError
【发布时间】：2014-04-08 14:56:52
【问题描述】：

当我分配line_to_be_added 变量时，我得到一个KeyError。可能是什么原因？

for key in PL_HASH_ON_FIRST_TWO_PARTS.keys():
    total_count=0
    print key, '\n'
    for pl_name in sorted(PL_HASH_ON_FIRST_TWO_PARTS[key]):
        print pl_name,'\n'
        count = PL_DICT_COUNT[pl_name]
        plTable = plTable + "<tr><td>%s</td><td>%d</td><td>%d</td><td>%d</td><td>%d</td><td>%d</td><td>%d</td><td>%d</td><td>%d</td><td>%d</td></tr>"%(pl_name, PL_NAME_DICT[pl_name][last_six_months[7]], PL_NAME_DICT[pl_name][last_six_months[6]], PL_NAME_DICT[pl_name][last_six_months[5]], PL_NAME_DICT[pl_name][last_six_months[4]], PL_NAME_DICT[pl_name][last_six_months[3]], PL_NAME_DICT[pl_name][last_six_months[2]], PL_NAME_DICT[pl_name][last_six_months[1]], PL_NAME_DICT[pl_name][last_six_months[0]], count)
        if key in count_bag_wise:
            for i in range(0,7):
                print last_six_months[i],'\n'
                count_bag_wise[key][last_six_months[i]]+=PL_NAME_DICT[pl_name][last_six_months[i]]
        else:
            count_bag_wise[key]=dict()
            for i in range(0,7):
                count_bag_wise[key][last_six_months[i]]=0
                count_bag_wise[key][last_six_months[i]]+=PL_NAME_DICT[pl_name][last_six_months[i]]
        TOTAL_COUNT += count
        total_count += count
    line_to_be_added="<tr><td>%s</td><td>%d</td><td>%d</td><td>%d</td><td>%d</td><td>%d</td><td>%d</td><td>%d</td><td>%d</td><td>%d</td></tr>"%(pl_name.split('.')[0]+'.'+pl_name.split('.')[1]+'.*', count_bag_wise[key][last_six_months[7]],count_bag_wise[key][last_six_months[6]], count_bag_wise[key][last_six_months[5]],count_bag_wise[key][last_six_months[4]],count_bag_wise[key][last_six_months[3]], count_bag_wise[key][last_six_months[2]],count_bag_wise[key][last_six_months[1]],count_bag_wise[key][last_six_months[0]], total_count)
    print line_to_be_added
    plTable = plTable +line_to_be_added

【问题讨论】：

ALCAPS 标题收到为大喊大叫。请不要那样做。
请同时修正缩进：每级四个空格，请不要使用制表符。
对于触发异常的key 的特定值，PL_HASH_ON_FIRST_TWO_PARTS 包含什么？很可能这是一个空列表，ergo count_bag_wise[key] 永远不会设置。

标签： python dictionary hashmap

【解决方案1】：

您永远不会设置last_six_months[7] 键：

for i in range(0,7):
    count_bag_wise[key][last_six_months[i]]=0
    count_bag_wise[key][last_six_months[i]]+=PL_NAME_DICT[pl_name][last_six_months[i]]

范围不包括7（结束值是唯一的）。

但是您的line_to_be_added 代码使用：

count_bag_wise[key][last_six_months[7]]

【讨论】：