Pythonic way to insert character

Question

I have two transform cases:

s = "foo bar" #-> "foo bar &"
s = "foo ! bar" # -> "foo & ! bar" -> notice not '&!'

I did it like this:

t = s.split("!", 1)
t[0] = t[0] + "  &"
" !".join(t)

What's a more pythonic way to do the same?

Answer 1

str.partition is built for the purpose of operator parsing:

p = s.partition(' !')
print p[0]+' &'+p[1]+p[2]

It is adapted to prefix and infix operator when parsing from left to right. The fact it always returns a 3-tuple allows to use it even when your operator is not found and apply an action on your result as shown above.

Answer 2

Not sure if this is any more pythonic, but the example above can be done as a one-liner.

>>> s = "foo ! bar"
>>> s = s.replace(' ! ', ' & ! ') if '!' in s else s + ' &'
>>> s
'foo & ! bar'