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
还有一种选择
from ansible.module_utils.parsing.convert_bool import boolean
boolean('no')
# False
boolean('yEs')
# True
boolean('true')
# True
其他回答
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
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
还有一种选择
from ansible.module_utils.parsing.convert_bool import boolean
boolean('no')
# False
boolean('yEs')
# True
boolean('true')
# True
该版本保留了int(value)等构造函数的语义,并提供了一种简单的方法来定义可接受的字符串值。
def to_bool(value):
valid = {'true': True, 't': True, '1': True,
'false': False, 'f': False, '0': False,
}
if isinstance(value, bool):
return value
if not isinstance(value, basestring):
raise ValueError('invalid literal for boolean. Not a string.')
lower_value = value.lower()
if lower_value in valid:
return valid[lower_value]
else:
raise ValueError('invalid literal for boolean: "%s"' % value)
# Test cases
assert to_bool('true'), '"true" is True'
assert to_bool('True'), '"True" is True'
assert to_bool('TRue'), '"TRue" is True'
assert to_bool('TRUE'), '"TRUE" is True'
assert to_bool('T'), '"T" is True'
assert to_bool('t'), '"t" is True'
assert to_bool('1'), '"1" is True'
assert to_bool(True), 'True is True'
assert to_bool(u'true'), 'unicode "true" is True'
assert to_bool('false') is False, '"false" is False'
assert to_bool('False') is False, '"False" is False'
assert to_bool('FAlse') is False, '"FAlse" is False'
assert to_bool('FALSE') is False, '"FALSE" is False'
assert to_bool('F') is False, '"F" is False'
assert to_bool('f') is False, '"f" is False'
assert to_bool('0') is False, '"0" is False'
assert to_bool(False) is False, 'False is False'
assert to_bool(u'false') is False, 'unicode "false" is False'
# Expect ValueError to be raised for invalid parameter...
try:
to_bool('')
to_bool(12)
to_bool([])
to_bool('yes')
to_bool('FOObar')
except ValueError, e:
pass
下面是我用来评估字符串真实性的东西:
def as_bool(val):
if val:
try:
if not int(val): val=False
except: pass
try:
if val.lower()=="false": val=False
except: pass
return bool(val)
与使用eval的结果大致相同,但更安全。