True vs False

[Skaperen]

i am reading in data, splitting it, etc, and getting strings with 'True' and 'False', such as reading from python source code.
i want to convert these strings to boolean.  if they were decimal numbers i could use int() or float(), but bool() ...

Output:
Python 3.5.2 (default, Nov 17 2016, 17:05:23) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> bool('True')
True
>>> bool('False')
True
>>> 

... does not work that way.

so maybe i can do:

Output:
Python 3.5.2 (default, Nov 17 2016, 17:05:23) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 'False'=='True'
False
>>> 'True'=='True'
True
>>> 

so far so good, but a bad string ...

Output:
Python 3.5.2 (default, Nov 17 2016, 17:05:23) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 'Maybe'=='True'
False
>>> 

... does not do so well (an exception would be nice).  any pythonic suggestions?  converting 'true' and 'false' and 'TRUE' and 'FALSE' would be a plus.

[buran]

def str_to_bool(my_str):
    my_str = my_str.lower()
    return my_str in ('true', 'false') and my_str == 'true'

for s in ('True', 'False', 'true', 'false', 'Maybe', 'maybe'):
    print '{} -> {}'.format(s, str_to_bool(s))

Output:
True -> True
False -> False
true -> True
false -> False
Maybe -> False
maybe -> False

or even

def str_to_bool(my_str):
    return my_str.lower() == 'true'

for s in ('True', 'False', 'true', 'false', 'Maybe', 'maybe'):
    print '{} -> {}'.format(s, str_to_bool(s))

Output:
True -> True
False -> False
true -> True
false -> False
Maybe -> False
maybe -> False

[buran]

Sorry, I didn't read it right - you want exception for not valid boolean string

def str_to_bool(my_str):
    _my_str = my_str.lower()
    if not _my_str in ('true', 'false'):
        raise ValueError('{} has no boolean meaning'.format(my_str))
    return _my_str == 'true'

for s in ('True', 'False', 'true', 'false', 'Maybe', 'maybe'):
    try:
        print '{} -> {}'.format(s, str_to_bool(s))
    except ValueError as ve:
        print ve[0]

Output:
True -> True
False -> False
true -> True
false -> False
Maybe has no boolean meaning
maybe has no boolean meaning

[wavic]

I think this is the simplest way

def to_bool(text):
   booleans = {'true': True, 'false': False}
   return booleans[text.lower()]

Or maybe @burans code

def str_to_bool(my_str):
    return my_str.lower() == 'true'

[Skaperen]

yeah, 'Maybe' has no special meaning, yet

[buran]

def to_bool(text):
    booleans = {'true': True, 'false': False}
    return booleans[text.lower()]

I like this one, only the exception in this case will be KeyError

[Skaperen]

ok to shorten it a bit:

def to_bool(text):
   return {'true': True, 'false': False}[text.lower()]

---

or:

def to_bool(text):
  return {'true':True,'false':False,'yes':True,'no':False,'t':True,'f':False,'y':True,'n':False}[text.lower()]

[wavic]

def to_bool(text):
    booleans = {'true': True, 'false': False}
    return booleans[text.lower()]

I like this one, only the exception in this case will be KeyError

Hm!
It works here:

In [1]: def to_bool(text):
   ...:     booleans = {'true': True, 'false': False}
   ...:     return booleans[text.lower()]
   ...: 

In [2]: to_bool('True')
Out[2]: True

In [3]: to_bool('False')
Out[3]: False

[buran]

Hm!
It works here:

I mean, the error that will be raised if text is not 'true' or 'false', but e.g. 'maybe'
It's ok to raise it, becasue that is what Skaperen wants. Just mention that it will be different than the one I raise in my code above

[Leorelp]

Oh nice topik, had found a lot of usefull info! Thanks!