Regex to remove duplicate letters but not numbers

Question

What is the appropriate regex to remove adjacent duplicate letters but not numbers?

For example:

p11ppppl  --> p11pl

I had the f

Answer 1

I would do it like this (visualized here):

/([a-zA-Z])(?=\1)/g

Here's an example in Python:

In [21]: re.sub(r'([a-zA-Z])(?=\1)', '', 'p11ppppl')
Out[21]: 'p11pl'

You could also use:

/([\D])(?=\1)/g

for everything except digits, or:

/([\w])(?=\1)/g

for all "word characters".

As @Casimir et Hippolyte mentioned in the comments, we can also use:

/([a-zA-Z])\1+/g

with \1 as the replacement string, which may be a better approach.