python is_date
时间: 2024-05-12 14:14:56 浏览: 9
`is_date`不是Python内置的函数,但你可以使用Python的datetime模块来检查一个字符串是否为日期。
以下是一个示例代码,可以检查一个字符串是否为日期:
```python
from datetime import datetime
def is_date(string, format):
try:
datetime.strptime(string, format)
return True
except ValueError:
return False
```
你可以使用这个函数来检查一个字符串是否为日期,例如:
```python
string = '2021-12-31'
format = '%Y-%m-%d'
if is_date(string, format):
print('This is a valid date')
else:
print('This is not a valid date')
```
这将输出:“This is a valid date”。
相关问题
python:KeyError: 'trade_date'
This error occurs when you are trying to access a key in a dictionary that does not exist. In this case, it seems like you are trying to access the key 'trade_date' but it is not present in the dictionary.
To fix this error, you should check the dictionary to ensure that the key 'trade_date' exists before trying to access it. You can use the `in` keyword to check if a key exists in a dictionary.
For example:
```
if 'trade_date' in my_dict:
# Access the value of the 'trade_date' key
trade_date = my_dict['trade_date']
else:
# Handle the case where the 'trade_date' key does not exist
print("The 'trade_date' key does not exist in the dictionary.")
```
Alternatively, you can use the `get()` method of the dictionary, which returns `None` if the key does not exist:
```
# Access the value of the 'trade_date' key, or return None if it does not exist
trade_date = my_dict.get('trade_date')
if trade_date is not None:
# Do something with the 'trade_date' value
print(trade_date)
else:
# Handle the case where the 'trade_date' key does not exist
print("The 'trade_date' key does not exist in the dictionary.")
```
Traceback (most recent call last): File "D:\work\works\pycharm\pythonProject\res_doLoad.py", line 60, in <module> if is_valid_date(i[1]['合同到期时间']): File "D:\work\works\pycharm\pythonProject\res_doLoad.py", line 48, in is_valid_date datetime.strptime(date_str, '%Y-%m-%d') TypeError: strptime() argument 1 must be str, not datetime.datetime
这个错误的意思是你传给 `strptime()` 方法的第一个参数应该是一个字符串类型,但是实际上传入的是一个 `datetime.datetime` 类型的对象。你需要先将 `datetime.datetime` 类型的对象转换为字符串类型,再传给 `strptime()` 方法。
你可以使用 `strftime()` 方法将 `datetime.datetime` 类型的对象转换为字符串类型。例如:
```python
date_str = i[1]['合同到期时间'].strftime('%Y-%m-%d')
```
然后再将 `date_str` 传给 `strptime()` 方法即可。
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