python - How to pass a variable to unicode/raw (ur"") conversion function -

i have no problem performing following function when taking actual text:

in [7]: str = ur"foo 20\n40%"  in [8]: str out[8]: u'foo 20\\n40%' 

but in actual case word "foo 20\n40%" stored in variable mystring. whats way that? tried failed:

in [13]: mynewstr = ur(mystr) --------------------------------------------------------------------------- nameerror                                 traceback (most recent call last) <ipython-input-13-0379c497611f> in <module>() ----> 1 mynewstr = ur(mystr)  nameerror: name 'ur' not defined 

if source string consists of ascii characters example does, it's easy:

mynewstr = unicode(mystr) 

otherwise need know encoding of original string bytes , use convert unicode. e.g. if know source utf-8:

mynewstr = mystr.decode('utf-8') 

e.g.

>>> print mystring foo 20\n40% >>> unicode(mystring) u'foo 20\\n40%' >>> mystring.decode('utf-8') u'foo 20\\n40%'