Regex to compare strings with Umlaut and non-Umlaut variations
Solution 1
something like
tr = {"ä":"ae", "ü":"ue", "ö":"oe", "ß":"ss" }
replaceUmlauts = function(s) {
return s.replace(/[äöüß]/g, function($0) { return tr[$0] })
}
compare = function(a, b) {
return replaceUmlauts(a) == replaceUmlauts(b)
}
alert(compare("grüße", "gruesse"))
you can easily extends this by adding more entries to "tr"
not quite elegant, but works
Solution 2
I have another way : ( purpose : sorting arrays )
function umlaut(str) {
return str
.replace(/Â|À|Å|Ã/g, "A")
.replace(/â|à|å|ã/g, "a")
.replace(/Ä/g, "AE")
.replace(/ä/g, "ae")
.replace(/Ç/g, "C")
.replace(/ç/g, "c")
.replace(/É|Ê|È|Ë/g, "E")
.replace(/é|ê|è|ë/g, "e")
.replace(/Ó|Ô|Ò|Õ|Ø/g, "O")
.replace(/ó|ô|ò|õ/g, "o")
.replace(/Ö/g, "OE")
.replace(/ö/g, "oe")
.replace(/Š/g, "S")
.replace(/š/g, "s")
.replace(/ß/g, "ss")
.replace(/Ú|Û|Ù/g, "U")
.replace(/ú|û|ù/g, "u")
.replace(/Ü/g, "UE")
.replace(/ü/g, "ue")
.replace(/Ý|Ÿ/g, "Y")
.replace(/ý|ÿ/g, "y")
.replace(/Ž/g, "Z")
.replace(/ž/, "z");
}
Solution 3
In addition to stereofrogs answer:
tr = {"\u00e4":"ae", "\u00fc":"ue", "\u00f6":"oe", "\u00df":"ss" }
ersetzeUmlauts = function(s) {
return s.replace(/[\u00e4|\u00fc|\u00f6|\u00df]/g, function($0) { return tr[$0] })
}
I was dealing with Umlauts in an Aptana/Eclipse script and the normal characters ('ä' etc.) didn't do the trick for me.
Solution 4
Regular expressions aren't quite powerful enough to do this properly, though you could hack it into almost working with them.
What you want is called Unicode Normalization. A Normalized string is one converted to a common form so you can compare them. You tagged your post "javascript", however, Javascript doesn't have a built in standard library to do this, and I am not aware of one offhand. Most server-side languages do have one, though. For example, the Normalizer Class in PHP. Python and Perl have equivalents, as do Microsoft stuff, I'm sure.
Check out the wikipedia article on Unicode Equivalence for more information.
Solution 5
One way is to process your regexp 'input' so that it replaces for example 'ä' with (ae|ä)' - not hardcode the mappings to your regexps. I am completely ignorant to javascript (ok, i know document.write() but that's about it) - but here is the same in pseudo code;
instead of doing
regexp_match("Grüße|Gruesse",somestring)
You should do something like:
mappings = (("ä","ae"),("ö","oe"),("ü","ue"))
def my_regexp_match(regexp,input) {
for key,value in mappings {
new_regexp = regexp.replace(key,"("+key+"|"+value+")")
}
regexp_match(new_regexp,input)
}
my_regexp_match("Grüße",somestring)
Sorry for being so "pythonic" - I do not know if you have re.compile() -like structure in javascript, but if you do - you should do the for -loop when compiling the matcher, not in my_regexp_match()
davek
Updated on June 12, 2022Comments
-
davek almost 2 years
Can anyone help me with a javascript regular expression that I can use to compare strings that are the same, taking into acccount their non-Umlaut-ed versions.
for example, in German the word
Grüße
can also be writtenGruesse
. These two strings are to be considered identical. The mappings (ignoring casings for the moment) are:- ä = ae
- ü = ue
- ö = oe
- ß = ss
As there are not many "couplets" to consider I could do a replace for each variation, but I'm wondering if there is a more elegant way, especially as this use case might need to be extended in future to include e.g. Scandanavian characters...