Vim Regex Capture Groups [bau -> byau : ceu -> cyeu]

Question

I have a list of words:

bau
ceu
diu
fou
gau

I want to turn that list into:

byau
cyeu
dyiu
fyou
gyau

I uns

Answer 1

If you don't want to escape the capturing groups with backslashes (this is what you've missed), prepend \v to turn Vim's regular expression engine into very magic mode:

:%s/\v(\w)(\w\w)/\1y\2/g