Hi, I'm needing to convert a string in CamelCase to separate scripts, I've been trying a bit of regular expressions but I can not get any part of it, the idea is to enter a string in CamelCase:
Entry:
'HolaMundoCruel'
Exit:
'hola-mundo-cruel'
Thanks
You can use re.sub to subtitle each match (in this case a capital letter inside the chain) by another given string (in this case '-'). To remove capitals you can use the lower method of the class str :
import re
pattP = re.compile(r'(.)([A-Z][a-z]+)')
pattF = re.compile('([a-z0-9])([A-Z])')
def camel_a_guiones(cadena):
return pattF.sub(r'-', pattP.sub(r'-', cadena)).lower()
print(camel_a_guiones('HolaMundoCruel'))
Another alternative using re.finditer to separate the words (this is valid also if we want to obtain a list of the words contained in the camel). Having this it is enough to rejoin them using the method join() of str :
import re
patt = re.compile(r'.+?(?:(?<=[a-z0-9])(?=[A-Z])|(?<=[A-Z])(?=[A-Z][a-z])|$)')
def camel_a_guiones(cadena):
return '-'.join(m.group(0) for m in re.finditer(patt, cadena)).lower()
print(camel_a_guiones('HolaMundoCruel'))
Output of both:
hello-world-cruel
Let's try to match the beginning of each word. There are 2 types of words in Pascal Notation :
Words started in uppercase, followed by at least one lower case
r"[A-Z][a-z]"
In this case, we are only interested in verifying that it is followed by a lowercase letter (it is the only relevant thing to put a hyphen before and lower case).
Although there could also be digits between the two letters, and we added it:
r"[A-Z]\d*[a-z]"
Acronyms (consecutive capital letters).
r"[A-Z][A-Z\d]*(?=[A-Z]|$)"
Matches 1 upper case, followed by uppercase or digits [A-Z][A-Z\d]* .
But also, that is followed by another capital letter or the end of the text (?=[A-Z]|$) .
That way, we avoid consuming the next word. For example,
HTML in HTMLFormateado . HTML in FormatoHTML .
Putting the two previous expressions together in one, we are left with:
r"[A-Z](?:[A-Z\d]*(?=[A-Z]|$)|\d*[a-z])"
This expression already matches all cases. If we replace with r"-\g<0>" (a hyphen followed by the text that matched), we have:
>>> import re >>> re.sub(r"[A-Z](?:[A-Z\d]*(?=[A-Z]|$)|\d*[a-z])", r"-\g", "FormatoHTMLConCSS") '-Formato-HTML-Con-CSS'
Do not insert scripts at the beginning of the text
To avoid inserting hyphens at the beginning, we will pass a function as an argument to check, in each replacement, if match.start() is 0 . If it is the first word (it starts at position 0), we do not use a script, otherwise we precede a script.
Within the function, we use str.lower() to take to lowercase.
import re
patron = r"[A-Z]\d*(?:[A-Z\d]*(?=[A-Z]|$)|[a-z])"
pascal = re.compile(patron)
def pascal_kebab(cadena):
def insertar_separador(match):
return ("-" if match.start() else "") + match.group().lower()
return pascal.sub(insertar_separador, cadena)
Convert from PascalCase to kebab-case.
We use exactly the same logic as in the last code, with a lambda.
import re
pascal = re.compile(r"[A-Z]\d*(?:[A-Z\d]*(?=[A-Z]|$)|[a-z])")
def pascal_kebab(cadena):
return pascal.sub(lambda m: ("-" if m.start() else "") + m.group().lower(), cadena)
Tests:
pruebas = ['VerHTMLDePag', 'Ver2HTMLDePag', 'Ver2HTMLPag2Info', 'HTMLFomatoPag',
'HTMLConXML', 'HTML5FomatoPag','HTML5ConXML', 'HTML5ConCSS3',
'HTML', 'VerQ', 'A2BFormato', 'Formato',
'SFormato'
]
for prueba in pruebas:
print("%-16s => %s" % (prueba, pascal_kebab(prueba)))
Result:
VerHTMLDePag => ver-html-de-pag Ver2HTMLDePag => ver2-html-de-pag Ver2HTMLPag2Info => ver2-html-pag2-info HTMLFomatoPag => html-fomato-pag HTMLConXML => html-con-xml HTML5FomatoPag => html5-fomato-pag HTML5ConXML => html5-con-xml HTML5ConCSS3 => html5-con-css3 HTML => html VerQ => ver-q A2BFormato => a2b-formato Formato => formato SFormato => s-formato
Demo: