how to replace one letter in an string python code example

Example 1: python replace letters in string

my_text = 'Aello world'
my_text = my_text.replace(my_text[0], 'H')
print (my_text)

Example 2: replace characters in string python

>>> a = '&#'
>>> print a.replace('&', r'\&')
\&#
>>> print a.replace('#', r'\#')
&\#
>>>