Python unicode escapes either are 4 hex digits (\uabcd
) or 8 (\Uabcdabcd
); for a codepoint beyond U+FFFF you need to use the latter (a capital U), make sure to left-fill with enough zeros:
>>> '\U0001D15D'
''
>>> '\U0001D15D'.encode('unicode_escape')
b'\\U0001d15d'
(And yes, the U+1D15D codepoint (MUSICAL SYMBOL WHOLE NOTE) is in the above example, but your browser font may not be able to render it, showing a place-holder glyph (a box or question mark) instead.
Because you used a \uabcd
escape, you replaced a
in abc
with two characters, the codepoint U+1D15 (ᴕ
, latin letter small capital ou), and the ASCII character D
. Using a 32-bit unicode literal works:
>>> import re
>>> print(re.sub('a', '\U0001D15D', 'abc' ))
bc
>>> print(re.sub('a', u'\U0001D15D', 'abc' ).encode('unicode_escape'))
b'\\U0001d15dbc'
where again the U+1D15D codepoint could be displayed by your font as a placeholder glyph instead.