Python pattern match a string

Question

I am trying to pattern match a string, so that if it ends in the characters 'std' I split the last 6 characters and append a different prefix.

I am assuming I can do this with regular expressions and re.split, but I am unsure of the correct notation to append a new prefix and take last 6 chars based on the presence of the last 3 chars.

regex = r"([a-zA-Z])"
if re.search(regex, "std"):
    match = re.search(regex, "std")

#re.sub(r'\Z', '', varname)

I think regex is a bit of overkill for this. Try endswith. — glibdud
– glibdud, Commented Jul 10, 2017 at 15:22

Daniel Roseman · Accepted Answer · 2017-07-10 15:22:55Z

4

You're confused about how to use regular expressions here. Your code is saying "search the string 'std' for any alphanumeric character".

But there is no need to use regexes here anyway. Just use string slicing, and .endswith:

if my_string.endswith('std'):
    new_string = new_prefix + mystring[-6:]

answered Jul 10, 2017 at 15:22

Daniel Roseman

602k68 gold badges910 silver badges923 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Artyer · Accepted Answer · 2017-07-10 15:22:53Z

3

No need for a regex. Just use standard string methods:

if s.endswith('std'):
    s = s[:-6] + new_suffix

But if you had to use a regex, you would substitute a regex, you would substitute the new suffix in:

regex = re.compile(".{3}std$")

s = regex.sub(new_suffix, s)

answered Jul 10, 2017 at 15:22

Artyer

44.2k3 gold badges80 silver badges109 bronze badges

3 Comments

Błotosmętek Over a year ago

The OP said "new prefix", not "new suffix".

Artyer Over a year ago

@Błotosmętek He also said "append" instead of "prepend", so I wasn't quite sure.

Pectus Excavatum Over a year ago

Sorry for confusion, but yeah it just needs changed to '-6:'

Collectives™ on Stack Overflow

Python pattern match a string

2 Answers 2

Comments

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related