如何在Python中将字符串转换为布尔值?这个尝试返回True:
>>> bool("False")
True
如何在Python中将字符串转换为布尔值?这个尝试返回True:
>>> bool("False")
True
当前回答
我必须这么做……所以,也许姗姗来迟——但有人可能会发现它很有用
def str_to_bool(input, default):
"""
| Default | not_default_str | input | result
| T | "false" | "true" | T
| T | "false" | "false" | F
| F | "true" | "true" | T
| F | "true" | "false" | F
"""
if default:
not_default_str = "false"
else:
not_default_str = "true"
if input.lower() == not_default_str:
return not default
else:
return default
其他回答
def str2bool(str):
if isinstance(str, basestring) and str.lower() in ['0','false','no']:
return False
else:
return bool(str)
想法:检查你是否希望字符串被计算为False;否则bool()对于任何非空字符串返回True。
您可能已经有了一个解决方案,但对于其他人来说,他们正在寻找一种方法,将值转换为布尔值,使用“标准”假值,包括None,[],{}和“”,除了false, no和0。
def toBoolean( val ):
"""
Get the boolean value of the provided input.
If the value is a boolean return the value.
Otherwise check to see if the value is in
["false", "f", "no", "n", "none", "0", "[]", "{}", "" ]
and returns True if value is not in the list
"""
if val is True or val is False:
return val
falseItems = ["false", "f", "no", "n", "none", "0", "[]", "{}", "" ]
return not str( val ).strip().lower() in falseItems
这是我的版本。它同时检查正值和负值列表,对于未知值引发异常。它不接收字符串,但任何类型都可以。
def to_bool(value):
"""
Converts 'something' to boolean. Raises exception for invalid formats
Possible True values: 1, True, "1", "TRue", "yes", "y", "t"
Possible False values: 0, False, None, [], {}, "", "0", "faLse", "no", "n", "f", 0.0, ...
"""
if str(value).lower() in ("yes", "y", "true", "t", "1"): return True
if str(value).lower() in ("no", "n", "false", "f", "0", "0.0", "", "none", "[]", "{}"): return False
raise Exception('Invalid value for boolean conversion: ' + str(value))
示例:
>>> to_bool(True)
True
>>> to_bool("tRUe")
True
>>> to_bool("1")
True
>>> to_bool(1)
True
>>> to_bool(2)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "<stdin>", line 9, in to_bool
Exception: Invalid value for boolean conversion: 2
>>> to_bool([])
False
>>> to_bool({})
False
>>> to_bool(None)
False
>>> to_bool("Wasssaaaaa")
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "<stdin>", line 9, in to_bool
Exception: Invalid value for boolean conversion: Wasssaaaaa
>>>
我使用
# function
def to_bool(x):
return x in ("True", "true", True)
# test cases
[[x, to_bool(x)] for x in [True, "True", "true", False, "False", "false", None, 1, 0, -1, 123]]
"""
Result:
[[True, True],
['True', True],
['true', True],
[False, False],
['False', False],
['false', False],
[None, False],
[1, True],
[0, False],
[-1, False],
[123, False]]
"""
JSON解析器在将字符串转换为合理的python类型时也很有用。
>>> import json
>>> json.loads("false".lower())
False
>>> json.loads("True".lower())
True