Python 忽略 KeyError 并继续程序
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Ignore KeyError and continue program
提问by jevans
In Python 3 I have a program coded as below. It basically takes an input from a user and checks it against a dictionary (EXCHANGE_DATA) and outputs a list of information.
在 Python 3 中，我有一个如下编码的程序。它基本上从用户那里获取输入，并根据字典 (EXCHANGE_DATA) 对其进行检查并输出信息列表。
from shares import EXCHANGE_DATA
portfolio_str=input("Please list portfolio: ")
portfolio_str= portfolio_str.replace(' ','')
portfolio_str= portfolio_str.upper()
portfolio_list= portfolio_str.split(',')
print()
print('{:<6} {:<20} {:>8}'.format('Code', 'Name', 'Price'))
EXCHANGE_DATA = {code:(share_name,share_value) for code, share_name, share_value in EXCHANGE_DATA}
try:
for code in portfolio_list:
share_name, share_value = EXCHANGE_DATA[code]
print('{:<6} {:<20} {:>8.2f}'.format(code, share_name, share_value))
except KeyError:
pass
Example input:
GPG,HNZ,DIL,FRE
示例输入：
GPG,HNZ,DIL,FRE
The output is as follows:
输出如下：
Please list portfolio: GPG,HNZ,DIL,FRE
Code Name Price
GPG Guinnesspeat 2.32
HNZ Heartland Nz 3.85
DIL Diligent 5.30
FRE Freightway 6.71
But if I have an input like:
但如果我有这样的输入：
AIR,HNZ,AAX,DIL,AZX
AIR,HNZ,AAX,DIL,AZX
where the terms AAX,AZXdo not exist in the dictionary (EXCHANGE_DATA)but the terms AIR,HNZ,DILdo. The program obviously would throw a KeyErrorexception but I have neutralized this with pass. The problem is after the passcode has been executed the program exits and I need it to continue on and execute the forloop on DIL. How do I do this?
AAX,AZX字典中不存在(EXCHANGE_DATA)这些术语但这些术语存在的地方AIR,HNZ,DIL。该程序显然会抛出KeyError异常，但我已经用pass. 问题是在执行pass代码后程序退出，我需要它继续并在for上执行循环DIL。我该怎么做呢？
采纳答案by Artsiom Rudzenka
Why not:
为什么不：
for code in portfolio_list:
try:
share_name, share_value = EXCHANGE_DATA[code]
print('{:<6} {:<20} {:>8.2f}'.format(code, share_name, share_value)
except KeyError:
continue
OR check dict.get method:
或检查 dict.get 方法：
for code in portfolio_list:
res = EXCHANGE_DATA.get(code, None)
if res:
print('{:<6} {:<20} {:>8.2f}'.format(code, *res)
And as @RedBaron mentioned:
正如@RedBaron 提到的：
for code in portfolio_list:
if code in EXCHANGE_DATA:
print('{:<6} {:<20} {:>8.2f}'.format(code, *EXCHANGE_DATA[code])
回答by Johannes Overmann
You just need to move the try/exceptblock into the for loop.
您只需要将try/except块移动到 for 循环中。
回答by xuanji
catch the exception in the loop
捕获循环中的异常
for code in portfolio_list:
try:
share_name, share_value = EXCHANGE_DATA[code]
print('{:<6} {:<20} {:>8.2f}'.format(code, share_name, share_value)
except KeyError:
pass
Edit: The more pythonic way would be to test if the dict has the element first
编辑：更pythonic的方法是测试dict是否首先包含元素
for code in portfolio_list:
if code in EXCHANGE_DATA:
share_name, share_value = EXCHANGE_DATA[code]
print('{:<6} {:<20} {:>8.2f}'.format(code, share_name, share_value)
