169 – Oxford comma

The function below turns a list of strings into a Human-readable enumeration that uses the Oxford comma:

def oxford_comma(strings):
    prefix = ", ".join(strings[:-1])
    ox_comma = "," if len(strings) > 2 else ""
    and_ = " and " if len(strings) > 1 else ""
    last = strings[-1] if strings else ""
    return prefix + ox_comma + and_ + last

Example usages:

print(oxford_comma(["like"]))
# like
print(oxford_comma(["like", "comment"]))
# like and comment
print(oxford_comma(["like", "comment", "subscribe"]))
# like, comment, and subscribe

The function oxford_comma demonstrates a useful technique for when you’re building complex strings.

Instead of using multiple if statements to conditionally append parts of the string to the result, build the final string out of smaller fragments. Then, a fragment that is unnecessary can be set to the empty string.

This keeps your code flatter and cleaner.