Develop Reference

Extracting dollar prices and numbers with comma as thousand separator from PDF converted to text format

I am trying to redact some pdfs with dollar amounts using c#. Below is what I have tried
#"/ (\d)(?= (?:\d{ 3})+(?:\.|$))| (\.\d\d ?)\d *$/ g"
#"(?<=each)(((\d*[,|.]\d{2,3}))*)"
#"(?<=each)(((\d*[,|.]\d{2,3}))*)"
#"\d+\.\d{2}"
Here are some test cases that it needs to match
76,249.25
131,588.00
7.09
21.27
420.42
54.77
32.848
3,056.12
0.009
0.01
32.85
2,948.59
$99,249.25
$9.0000
$1,800.0000
$1,000,000
Here are some test cases that it should not target
666-257-6443
F1A 5G9
Bolt, Locating, M8 x 1.25 x 30 L
Precision Washer, 304 SS, 0.63 OD x 0.31
Flat Washer 300 Series SS; Pack of 50
U-SSFAN 0.63-L6.00-F0.75-B0.64-T0.38-SC5.62
U-CLBUM 0.63-D0.88-L0.875
U-WSSS 0.38-D0.88-T0.125
U-BGHK 6002ZZ - H1.50
U-SSCS 0.38-B0.38
6412K42
Std Dowel, 3/8" x 1-1/2" Lg, Steel
2019.07.05
2092-002.0180
SHCMG 0.25-L1.00
280160717
Please note the c# portion is interfacing with iText 7 pdfSweep.
Guid g = new Guid();
CompositeCleanupStrategy strategy = new CompositeCleanupStrategy();
string guid = g.ToString();
string input = #"C:\Users\JM\Documents\pdftest\61882 _280011434 (1).pdf";
string output = #"C:\Users\JM\Documents\pdftest\61882 _2800011434 (1) x2" + guid+".pdf";
string regex = #"(?m)^\$?[0-9]{1,3}(?:,[0-9]{3})*(?:\.[0-9]+)?$";
strategy.Add(new RegexBasedCleanupStrategy(regex));
PdfDocument pdf = new PdfDocument(new PdfReader(input), new PdfWriter(output));
PdfAutoSweep autoSweep = new PdfAutoSweep(strategy);
autoSweep.CleanUp(pdf);
pdf.Close();
Please share your wisdom

You may use
\$?[0-9]{1,3}(?:,[0-9]{3})*(?:\.[0-9]+)?
Or, if the prices occur on whole lines:
^\$?[0-9]{1,3}(?:,[0-9]{3})*(?:\.[0-9]+)?$
See the regex demo
Bonus: To obtain only price values, you need to remove the ? after \$ to make it obligatory:
\$([0-9]{1,3}(?:,[0-9]{3})*(?:\.[0-9]+)?)
(I added a capturing group in case you need to access the number value separately from the $ char).
If you need to support any currency char, not just $, replace \$ with \p{Sc}.
Details
^ - start of string
\$? - an optional dollar symbol
[0-9]{1,3} - one to three digits
(?:,[0-9]{3})* - any 0 or more repetitions of a comma and then three digits
(?:\.[0-9]+)? - an optional sequence of a dot and then any 1 or more digits
$ - end of string.
C# check for a match:
if (Regex.IsMatch(str, #"^\$?[0-9]{1,3}(?:,[0-9]{3})*(?:\.[0-9]+)?$"))
{
// there is a match
}
pdfSweep notice:
Apply the fix from this answer. The point is that the line breaks are lost when parsing the text. The regex you need then is
#"(?m)^\$?[0-9]{1,3}(?:,[0-9]{3})*(?:\.[0-9]+)?\r?$"
where (?m) makes ^ and $ match start/end of lines and \r? is required as $ only matches before LF, not before CRLF in .NET regex.

Replace floating numbers in math equation with letter variables

I want to replace all the floating numbers from a mathematical expression with letters using regular expressions. This is what I've tried:
Regex rx = new Regex("[-]?([0-9]*[.])?[0-9]+");
string expression = "((-30+5.2)*(2+7))-((-3.1*2.5)-9.12)";
char letter = 'a';
while (rx.IsMatch(expression))
{
expression = rx.Replace(expression , letter.ToString(), 1);
letter++;
}
The problem is that if I have for example (5-2)+3 it will replace it to: (ab)+c
So it gets the -2 as a number but I don't want that.
I am not experienced with Regex but I think I need something like this:
Check for '-', if there is a one, check if there is a number or right parenthesis before it. If there is NOT then save the '-'.
After that check for digits + dot + digits
My above Regex also works with values like: .2 .3 .4 but I don't need that, it should be explicit: 0.2 0.3 0.4

Following the suggested logic, you may consider
(?:(?<![)0-9])-)?[0-9]+(?:\.[0-9]+)?
See the regex demo.
Regex details
(?:(?<![)0-9])-)? - an optional non-capturing group matching 1 or 0 occurrences of
(?<![)0-9]) - a place in string that is not immediately preceded with a ) or digit
- - a minus
[0-9]+ - 1+ digits
(?:\.[0-9]+)? - an optional non-capturing group matching 1 or 0 occurrences of a . followed with 1+ digits.
In code, it is better to use a match evaluator (see the C# demo online):
Regex rx = new Regex(#"(?:(?<![)0-9])-)?[0-9]+(?:\.[0-9]+)?");
string expression = "((-30+5.2)*(2+7))-((-3.1*2.5)-9.12)";
char letter = (char)96; // char before a in ASCII table
string result = rx.Replace(expression, m =>
{
letter++; // char is incremented
return letter.ToString();
}
);
Console.WriteLine(result); // => ((a+b)*(c+d))-((e*f)-g)

Regex - Trying to write match validation for Swedish Social Number

So I want the formats xxxxxx-xxxx AND xxxxxxxx-xxxx to be possible. I've managed to fix the first section before the dash, but the last four digits are troublesome. It does require to match at least 4 characters, but I also want the regex to return false if there's more than 4 characters. How do I do it?
This is how it looks so far:
var regex = new Regex(#"^\d{6,8}[-|(\s)]{0,1}\d{4}");
And this is the results:
var regex = new Regex(#"^\d{6,8}[-|(\s)]{0,1}\d{4}");
Match m = regex.Match("840204-2344");
Console.WriteLine(m.Success); // Outputs True
Match m = regex.Match("19840204-2344");
Console.WriteLine(m.Success); // Outputs True
Match m = regex.Match("19840204-23");
Console.WriteLine(m.Success); // Outputs false
Match m = regex.Match("19840204-2323423423");
Console.WriteLine(m.Success); // Outputs true, and this is what I don't want

The \d{6,8} pattern matches 6, 7 or 8 digits, so that will already invalidate your regex pattern. Besdies, [-|(\s)]{0,1} matches 1 or 0 -, (, ), | or whitespace chars, and will also match strings like 19840204|2323, 19840204(2323 and 19840204)2323.
You may use
^\d{6}(?:\d{2})?[-\s]?\d{4}$
See the regex demo.
Details
^ - start of string
\d{6} - 6 digits
(?:\d{2})? - optional 2 digits
[-\s]? - 1 or 0 - or whitespaces
\d{4} - 4 digits
$ - end of string.
To make \d only match ASCII digits, pass RegexOptions.ECMAScriptoption. Example:
var res = Regex.IsMatch(s, #"^\d{6}(?:\d{2})?[-\s]?\d{4}$", RegexOptions.ECMAScript);

You are forgetting the $ at the end:
var regex = new Regex(#"^(\d{6}|\d{8})-\d{4}$");
If you want to match the social security number anywhere in a string, you van also use \b to test for boundaries:
var regex = new Regex(#"\b(\d{6}|\d{8})-\d{4}\b");
Edit: I corrected the RegEx to fix the problems mentioned in the comments. The commentors are right, of course. In my earlier post I just wanted to explain why the RegEx matched the longer string.

Regex to get everything starting with # and removing everything after any non-included characters

I have the following:
Regex RgxUrl = new Regex("[^a-zA-Z0-9-_]");
foreach (var item in source.Split(' ').Where(s => s.StartsWith("#")))
{
var mention = item.Replace("#", "");
mention = RgxUrl.Replace(mention, "");
usernames.Add(mention);
}
CURRENT INPUT > OUTPUT
#fish and fries are #good > fish, good
#fish and fries and #Mary's beer are #good > fish, good, marys
DESIRED INPUT > OUTPUT
#fish and fries are #good > fish, good
#fish and fries and #Mary's beer are #good > fish, good, Mary
The key here is to remove anything that's after an offending character. How can this be achieved?

You split a string with a space, check if a chunk starts with #, then if yes, remove all the # symbols in the string, then use a regex to remove all non-alphanumeric, - and _ chars in the string and then add it to the list.
You can do that with a single regex:
var res = Regex.Matches(source, #"(?<!\S)#([a-zA-Z0-9-_]+)")
.Cast<Match>()
.Select(m=>m.Groups[1].Value)
.ToList();
Console.WriteLine(string.Join("; ", res)); // demo
usernames.AddRange(res); // in your code
See the C# demo
Pattern details:
(?<!\S) - there must not be a non-whitespace symbol immediately to the left of the current location (i.e. there must be a whitespace or start of string) (this lookbehind is here because the original code split the string with whitespace)
# - a # symbol (it is not part of the subsequent group because this symbol was removed in the original code)
([a-zA-Z0-9-_]+) - Capturing Group 1 (accessed with m.Groups[1].Value) matching one or more ASCII letters, digits, - and _ symbols.

Regex with balancing groups

I need to write regex that capture generic arguments (that also can be generic) of type name in special notation like this:
System.Action[Int32,Dictionary[Int32,Int32],Int32]
lets assume type name is [\w.]+ and parameter is [\w.,\[\]]+
so I need to grab only Int32, Dictionary[Int32,Int32] and Int32
Basically I need to take something if balancing group stack is empty, but I don't really understand how.
UPD
The answer below helped me solve the problem fast (but without proper validation and with depth limitation = 1), but I've managed to do it with group balancing:
^[\w.]+ #Type name
\[(?<delim>) #Opening bracet and first delimiter
[\w.]+ #Minimal content
(
[\w.]+
((?(open)|(?<param-delim>)),(?(open)|(?<delim>)))* #Cutting param if balanced before comma and placing delimiter
((?<open>\[))* #Counting [
((?<-open>\]))* #Counting ]
)*
(?(open)|(?<param-delim>))\] #Cutting last param if balanced
(?(open)(?!) #Checking balance
)$
Demo
UPD2 (Last optimization)
^[\w.]+
\[(?<delim>)
[\w.]+
(?:
(?:(?(open)|(?<param-delim>)),(?(open)|(?<delim>))[\w.]+)?
(?:(?<open>\[)[\w.]+)?
(?:(?<-open>\]))*
)*
(?(open)|(?<param-delim>))\]
(?(open)(?!)
)$

I suggest capturing those values using
\w+(?:\.\w+)*\[(?:,?(?<res>\w+(?:\[[^][]*])?))*
See the regex demo.
Details:
\w+(?:\.\w+)* - match 1+ word chars followed with . + 1+ word chars 1 or more times
\[ - a literal [
(?:,?(?<res>\w+(?:\[[^][]*])?))* - 0 or more sequences of:
,? - an optional comma
(?<res>\w+(?:\[[^][]*])?) - Group "res" capturing:
\w+ - one or more word chars (perhaps, you would like [\w.]+)
(?:\[[^][]*])? - 1 or 0 (change ? to * to match 1 or more) sequences of a [, 0+ chars other than [ and ], and a closing ].
A C# demo below:
var line = "System.Action[Int32,Dictionary[Int32,Int32],Int32]";
var pattern = #"\w+(?:\.\w+)*\[(?:,?(?<res>\w+(?:\[[^][]*])?))*";
var result = Regex.Matches(line, pattern)
.Cast<Match>()
.SelectMany(x => x.Groups["res"].Captures.Cast<Capture>()
.Select(t => t.Value))
.ToList();
foreach (var s in result) // DEMO
Console.WriteLine(s);
UPDATE: To account for unknown depth [...] substrings, use
\w+(?:\.\w+)*\[(?:\s*,?\s*(?<res>\w+(?:\[(?>[^][]+|(?<o>\[)|(?<-o>]))*(?(o)(?!))])?))*
See the regex demo