Split string keeping the separator without a starting space

Question

Hi I would like to split some strings like these using python re module :

str1 = "-t Hello World -a New Developr -d A description"
str2 = "-t Bye -a sometext -d a large description"

I must keep the - because I'm currently programming a python CLI project. I've tried using

re.split(r'(?=-)',aux)

but I recieved

['', '-t Hello World  ', '-a Author ', '-d Description ']

instead of

['-t Hello World', '-a Author', '-d Description']

Any recommendation?

Answer 1

Try applying the strip() method on the results.

foo = re.split(r'(?=-)',str1)
foo = [s.strip() for s in foo]

Answer 2

Use a negative lookbehind to avoid splitting at the start of the string: (?<!^)

Then strip each of the resulting strings.

for s in str1, str2:
    print([x.strip() for x in re.split(r'(?<!^)(?=\s+-)', str1)])

(I also added \s+ to avoid splitting words like Spider-Man .)

Output:

['-t Hello World', '-a New Developr', '-d A description']
['-t Hello World', '-a New Developr', '-d A description']

---

However, I'd recommend looking into libraries that can do this for you - maybe argparse and shlex to start, and I would question where these strings are coming from, cause normally you deal with command line arguments as a list before parsing, like this:

['-t', 'Hello', 'World', '-a', 'New', 'Developr', '-d', 'A', 'description']