Capitalize every 3rd letter in a string - Python [closed]

Answer 1

You can take a stride slice of an array which makes for a pretty and pythonic few lines:

s = "thisisareallylongstringwithlotsofletters"  

# convert to list
a = list(s)

#change every third letter in place with a list comprehension
a[2::3] = [x.upper() for x in a[2::3]]

#back to a string
s = ''.join(a)

# result: thIsiSarEalLylOngStrIngWitHloTsoFleTteRs

It's not clear what you want with spaces - this treats them like characters.