I have a List of words I want to ignore like this one :
public List<String> ignoreList = new List<String>()
{
"North",
"South",
"East",
"West"
};
For a given string, say "14th Avenue North"
I want to be able to remove the "North" part, so basically a function that would return "14th Avenue "
when called.
I feel like there is something I should be able to do with a mix of LINQ, regex and replace, but I just can't figure it out.
The bigger picture is, I'm trying to write an address matching algorithm. I want to filter out words like "Street", "North", "Boulevard", etc. before I use the Levenshtein algorithm to evaluate the similarity.
How about this:
string.Join(" ", text.Split().Where(w => !ignoreList.Contains(w)));
or for .Net 3:
string.Join(" ", text.Split().Where(w => !ignoreList.Contains(w)).ToArray());
Note that this method splits the string up into individual words so it only removes whole words. That way it will work properly with addresses like Northampton Way #123
that string.Replace
can't handle.
Regex r = new Regex(string.Join("|", ignoreList.Select(s => Regex.Escape(s)).ToArray()));
string s = "14th Avenue North";
s = r.Replace(s, string.Empty);
Something like this should work:
string FilterAllValuesFromIgnoreList(string someStringToFilter)
{
return ignoreList.Aggregate(someStringToFilter, (str, filter)=>str.Replace(filter, ""));
}
What's wrong with a simple for loop?
string street = "14th Avenue North";
foreach (string word in ignoreList)
{
street = street.Replace(word, string.Empty);
}
If you know that the list of word contains only characters that do not need escaping inside a regular expression then you can do this:
string s = "14th Avenue North";
Regex regex = new Regex(string.Format(@"\b({0})\b",
string.Join("|", ignoreList.ToArray())));
s = regex.Replace(s, "");
Result:
14th Avenue
If there are special characters you will need to fix two things:
\\b
will not match a whitespace followed by a symbol or vice versa. You may need to check for whitespace (or other separating characters such as punctuation) using lookaround assertions instead. Here's how to fix these two problems:
Regex regex = new Regex(string.Format(@"(?<= |^)({0})(?= |$)",
string.Join("|", ignoreList.Select(x => Regex.Escape(x)).ToArray())));
If it's a short string as in your example, you can just loop though the strings and replace one at a time. If you want to get fancy you can use the LINQ Aggregate method to do it:
address = ignoreList.Aggregate(address, (a, s) => a.Replace(s, String.Empty));
If it's a large string, that would be slow. Instead you can replace all strings in a single run through the string, which is much faster. I made a method for that in this answer .
LINQ makes this easy and readable. This requires normalized data though, particularly in that it is case-sensitive.
List<string> ignoreList = new List<string>()
{
"North",
"South",
"East",
"West"
};
string s = "123 West 5th St"
.Split(' ') // Separate the words to an array
.ToList() // Convert array to TList<>
.Except(ignoreList) // Remove ignored keywords
.Aggregate((s1, s2) => s1 + " " + s2); // Reconstruct the string
public static string Trim(string text)
{
var rv = text;
foreach (var ignore in ignoreList)
rv = rv.Replace(ignore, "");
return rv;
}
Updated For Gabe
public static string Trim(string text)
{
var rv = "";
var words = text.Split(" ");
foreach (var word in words)
{
var present = false;
foreach (var ignore in ignoreList)
if (word == ignore)
present = true;
if (!present)
rv += word;
}
return rv;
}
If you have a list, I think you're going to have to touch all the items. You could create a massive RegEx with all your ignore keywords and replace to String.Empty
.
Here's a start:
(^|\s+)(North|South|East|West){1,2}(ern)?(\s+|$)
If you have a single RegEx for ignore words, you can do a single replace for each phrase you want to pass to the algorithm.
Why not juts Keep It Simple ?
public static string Trim(string text)
{
var rv = text.trim();
foreach (var ignore in ignoreList) {
if(tv.EndsWith(ignore) {
rv = rv.Replace(ignore, string.Empty);
}
}
return rv;
}
You can do this using and expression if you like, but it's easier to turn it around than using a Aggregate. I would do something like this:
string s = "14th Avenue North"
ignoreList.ForEach(i => s = s.Replace(i, ""));
//result is "14th Avenue "
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