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Simplify regex code in C#: Add a space between a digit/decimal and unit

I have a regex code written in C# that basically adds a space between a number and a unit with some exceptions:
dosage_value = Regex.Replace(dosage_value, #"(\d)\s+", #"$1");
dosage_value = Regex.Replace(dosage_value, #"(\d)%\s+", #"$1%");
dosage_value = Regex.Replace(dosage_value, #"(\d+(\.\d+)?)", #"$1 ");
dosage_value = Regex.Replace(dosage_value, #"(\d)\s+%", #"$1% ");
dosage_value = Regex.Replace(dosage_value, #"(\d)\s+:", #"$1:");
dosage_value = Regex.Replace(dosage_value, #"(\d)\s+e", #"$1e");
dosage_value = Regex.Replace(dosage_value, #"(\d)\s+E", #"$1E");
Example:
10ANYUNIT
10:something
10 : something
10 %
40 e-5
40 E-05
should become
10 ANYUNIT
10:something
10: something
10%
40e-5
40E-05
Exceptions are: %, E, e and :.
I have tried, but since my regex knowledge is not top-notch, would someone be able to help me reduce this code with same expected results?
Thank you!

For your example data, you might use 2 capture groups where the second group is in an optional part.
In the callback of replace, check if capture group 2 exists. If it does, use is in the replacement, else add a space.
(\d+(?:\.\d+)?)(?:\s*([%:eE]))?
( Capture group 1
\d+(?:\.\d+)? match 1+ digits with an optional decimal part
) Close group 1
(?: Non capture group to match a as a whole
\s*([%:eE]) Match optional whitespace chars, and capture 1 of % : e E in group 2
)? Close non capture group and make it optional
.NET regex demo
string[] strings = new string[]
{
"10ANYUNIT",
"10:something",
"10 : something",
"10 %",
"40 e-5",
"40 E-05",
};
string pattern = #"(\d+(?:\.\d+)?)(?:\s*([%:eE]))?";
var result = strings.Select(s =>
Regex.Replace(
s, pattern, m =>
m.Groups[1].Value + (m.Groups[2].Success ? m.Groups[2].Value : " ")
)
);
Array.ForEach(result.ToArray(), Console.WriteLine);
Output
10 ANYUNIT
10:something
10: something
10%
40e-5
40E-05
As in .NET \d can also match digits from other languages, \s can also match a newline and the start of the pattern might be a partial match, a bit more precise match can be:
\b([0-9]+(?:\.[0-9]+)?)(?:[\p{Zs}\t]*([%:eE]))?

I think you need something like this:
dosage_value = Regex.Replace(dosage_value, #"(\d+(\.\d*)?)\s*((E|e|%|:)+)\s*", #"$1$3 ");
Group 1 - (\d+(\.\d*)?)
Any number like 123 1241.23
Group 2 - ((E|e|%|:)+)
Any of special symbols like E e % :
Group 1 and Group 2 could be separated with any number of whitespaces.
If it's not working as you asking, please provide some samples to test.

For me it's too complex to be handled just by one regex. I suggest splitting into separate checks. See below code example - I used four different regexes, first is described in detail, the rest can be deduced based on first explanation.
using System.Text.RegularExpressions;
var testStrings = new string[]
{
"10mg",
"10:something",
"10 : something",
"10 %",
"40 e-5",
"40 E-05",
};
foreach (var testString in testStrings)
{
Console.WriteLine($"Input: '{testString}', parsed: '{RegexReplace(testString)}'");
}
string RegexReplace(string input)
{
// First look for exponential notation.
// Pattern is: match zero or more whitespaces \s*
// Then match one or more digits and store it in first capturing group (\d+)
// Then match one ore more whitespaces again.
// Then match part with exponent ([eE][-+]?\d+) and store it in second capturing group.
// It will match lower or uppercase 'e' with optional (due to ? operator) dash/plus sign and one ore more digits.
// Then match zero or more white spaces.
var expForMatch = Regex.Match(input, #"\s*(\d+)\s+([eE][-+]?\d+)\s*");
if(expForMatch.Success)
{
return $"{expForMatch.Groups[1].Value}{expForMatch.Groups[2].Value}";
}
var matchWithColon = Regex.Match(input, #"\s*(\d+)\s*:\s*(\w+)");
if (matchWithColon.Success)
{
return $"{matchWithColon.Groups[1].Value}:{matchWithColon.Groups[2].Value}";
}
var matchWithPercent = Regex.Match(input, #"\s*(\d+)\s*%");
if (matchWithPercent.Success)
{
return $"{matchWithPercent.Groups[1].Value}%";
}
var matchWithUnit = Regex.Match(input, #"\s*(\d+)\s*(\w+)");
if (matchWithUnit.Success)
{
return $"{matchWithUnit.Groups[1].Value} {matchWithUnit.Groups[2].Value}";
}
return input;
}
Output is:
Input: '10mg', parsed: '10 mg'
Input: '10:something', parsed: '10:something'
Input: '10 : something', parsed: '10:something'
Input: '10 %', parsed: '10%'
Input: '40 e-5', parsed: '40e-5'
Input: '40 E-05', parsed: '40E-05'

How should be the regex for alphanumeric where alphabet only with combinations of"w" or "d" or "h"

I need the regex to validate the user entered string, the string may be of following formats.
ex: 1w 2d 1h or 2w 1h or 1w 2d. Likewise combinations of numbers and w,d and h.
I am looking for the regex to allow the combinations number and w or d or h.
Is it possible to have a regex like that way?

You could say you want
\d+ any number, 1 or more times
[wdh] one of w, d, h
(?: |$) space or end of string
Then put this in a group, loop it 1 or more times
(?: start of non-capture group
)+ end of non-capture group, 1 or more times
^ and $ start and end of string respectively
Result
^(?:\d+[wdh](?: |$))+$
Edit: I see you've added more requirements in the comments of your question, this regex will not fulfil your most recent requirements

We can try writing a rudimentary parser to check the input string.
string input = "1w 2d 1h";
string[] parts = Regex.Split(input, #"\s+");
bool success = true;
if (parts.Length > 3)
{
success = false;
}
else
{
Regex regex = new Regex(#"\d+(?:w|d|h)");
foreach (string part in parts)
{
Match match = regex.Match(part);
if (!match.Success)
{
success = false;
}
}
}
if (success)
{
Console.WriteLine("MATCH");
}
else
{
Console.WriteLine("NO MATCH");
}
This answer might carry its own weight if, in your C# application, you also needed to extract the numerical values of each component.

Try ^(?:\d+w ?)?(?:\d+d ?)?(?:\d+h)?$
Explaantion:
^ - match beginning of a string
(?:...) - non-capturing group
\d+ - match one or more digits
w, d, h - match literally w, d, h respectively
? - match preceeding pattern zero or one time
Demo

Finally, the following string seems to be working fine for me...
^(?:\d+w)?((?:\d+d)|(?: \d+d))?((?:\d+h)|(?: \d+h))?$
Thanks, everyone for helping.

This works for your requirement. Hope this helps! Ordering (w->d->h) guaranteed.
^(\d+w){0,1}\s*(\d+d){0,1}\s*(\d+h){0,1}$
Test cases:
10w 12d 11h
1w 2d
2w 1h
1d 1h
1d 1h
3w 2h

Regex C# Matching string from two words in exact order and returning capture of non-matched words

C# Regex
I have the following list of strings:
"New patient, brief"
"New patient, limited"
"Established patient, brief"
"Established patient, limited"
"New diet patient"
"Established diet patient"
"School Physical"
"Deposition, 1 hour"
"Deposition, 2 hour"
I would like to separate these strings into groups using regex.
The first pattern I see is:
"New" or "Established" -- will be the first word of the matched pattern. This word will need to be captured and returned. Of this pattern, "patient" must be present without need to capture. Any word after "patient" must be captured.
I've tried: ((?=.*\bNew\b))(?=.*\bpatient\b)([A-Za-z0-9\-]+)
but the return match gives:
Full match 0-3 `New`
Group 1. 0-0 ``
Group 2. 0-3 `New`
Not at all what I am looking for.
string input = "New patient, limited";
string pattern = #"((?=.*\bNew\b))(?=.*\bpatient\b)([A-Za-z0-9\-]+)";
MatchCollection matches = Regex.Matches(input, pattern);
GroupCollection groups = matches[0].Groups;
foreach (Match match in matches)
{
Console.WriteLine("First word: {0}", match.Groups[1].Value);
Console.WriteLine("Last words: {0}", match.Groups[2].Value);
Console.WriteLine();
}
Console.WriteLine();
Thank you for any help with this.
Edit #1
For strings like "New patient, limited"
output should be: "New" "limited"
For strings like "Deposition, 1 hour" where "hour" is present,
output should be: "Deposition, 1 hour"
For strings where there are no words after "patient" but "patient" is present, like
"New diet patient",
output should be: "New" "diet"
For strings where neither "patient" nor "hour" is present, the entire string should be returned. i.e like "School Physical" should return the entire string,
"School Physical".
As I said, this is my ultimate quest. At the moment, I am trying to focus on separating out only the first pattern :). Much Thanks.

I suggest using
^(?:(?!\b(?:New|Established)\b).)*$|\b(New|Established)\s+(?:patient\b\W*)?(.+)
See the regex demo
Details
^(?:(?!\b(?:New|Established)\b).)*$ - any string that has no New or Established as whole words
| - or
\b(New|Established) - a whole word New or Established (put into Group 1)
\s+ - 1+ whitespaces
(?:patient\b\W*)? - an optional non-capturing group matching 1 or 0 occurrences of patient followed with word boundary and 0+ non-word chars
(.+) - Group 2: any 1 or more chars other than line break chars.
The code will look like
var match = Regex.Match(s, #"^(?:(?!\b(?:New|Established)\b).)*$|\b(New|Established)\s+(?:patient\b\W*)?(.+)");
If Group 1 is not matched (!match.Groups[1].Success), grab the whole match, match.Value. Else, grab match.Groups[1].Value and match.Groups[2].Value.
Results:

What RegEx string will find the last (rightmost) group of digits in a string?

Looking for a regex string that will let me find the rightmost (if any) group of digits embedded in a string. We only care about contiguous digits. We don't care about sign, commas, decimals, etc. Those, if found should simply be treated as non-digits just like a letter.
This is for replacement/incrementing purposes so we also need to grab everything before and after the detected number so we can reconstruct the string after incrementing the value so we need a tokenized regex.
Here's examples of what we are looking for:
"abc123def456ghi" should identify the'456'
"abc123def456ghi789jkl" should identify the'789'
"abc123def" should identify the'123'
"123ghi" should identify the'123'
"abc123,456ghi" should identify the'456'
"abc-654def" should identify the'654'
"abcdef" shouldn't return any match
As an example of what we want, it would be something like starting with the name 'Item 4-1a', extracting out the '1' with everything before being the prefix and everything after being the suffix. Then using that, we can generate the values 'Item 4-2a', 'Item 4-3a' and 'Item 4-4a' in a code loop.
Now If I were looking for the first set, this would be easy. I'd just find the first contiguous block of 0 or more non-digits for the prefix, then the block of 1 or more contiguous digits for the number, then everything else to the end would be the suffix.
The issue I'm having is how to define the prefix as including all (if any) numbers except the last set. Everything I try for the prefix keeps swallowing that last set, even when I've tried anchoring it to the end by basically reversing the above.

How about:
^(.*?)(\d+)(\D*)$
then increment the second group and concat all 3.
Explanation:
^ : Begining of string
( : start of 1st capture group
.*? : any number of any char not greedy
) : end group
( : start of 2nd capture group
\d+ : one or more digits
) : end group
( : start of 3rd capture group
\D* : any number of non digit char
) : end group
$ : end of string
The first capture group will match all characters until the first digit of last group of digits before the end of the string.
or if you can use named group
^(?<prefix>.*?)(?<number>\d+)(?<suffix>\D*)$

Try next regex:
(\d+)(?!.*\d)
Explanation:
(\d+) # One or more digits.
(?!.*\d) # (zero-width) Negative look-ahead: Don't find any characters followed with a digit.
EDIT (OFFTOPIC of the question):: This answer is incorrect but this question has already been answered in other posts so to avoid delete this one I will use this same regex other way, for example in Perl could be used like this to get same result as in C# (increment last digit):
s/(\d+)(?!.*\d)/$1 + 1/e;

You can also try little bit simpler version:
(\d+)[^\d]*$

This should do it:
Regex regexObj = new Regex(#"
# Grab last set of digits, prefix and suffix.
^ # Anchor to start of string.
(.*) # $1: Stuff before last set of digits.
(?<!\d) # Anchor start of last set of digits.
(\d+) # $2: Last set of one or more digits.
(\D*) # $3: Zero or more trailing non digits.
$ # Anchor to end of string.
", RegexOptions.IgnorePatternWhitespace);

What about not using Regex. Here's code snippet (for console)
string[] myStringArray = new string[] { "abc123def456ghi", "abc123def456ghi789jkl", "abc123def", "123ghi", "abcdef","abc-654def" };
char[] numberSet = new char[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };
char[] filterSet = new char[] {'a','b','c','d','e','f','g','h','i','j','k','l','m',
'n','o','p','q','r','s','t','u','v','w','x','y','z','-'};
foreach (string myString in myStringArray)
{
Console.WriteLine("your string - {0}",myString);
int index1 = myString.LastIndexOfAny(numberSet);
if (index1 == -1)
Console.WriteLine("no number");
else
{
string mySubString = myString.Substring(0,index1 + 1);
string prefix = myString.Substring(index1 + 1);
Console.WriteLine("prefix - {0}", prefix);
int index2 = mySubString.LastIndexOfAny(filterSet);
string suffix = myString.Substring(0, index2 + 1);
Console.WriteLine("suffix - {0}",suffix);
mySubString = mySubString.Substring(index2 + 1);
Console.WriteLine("number - {0}",mySubString);
Console.WriteLine("_________________");
}
}
Console.Read();

Regular Expression to find separate words?

Here's a quickie for your RegEx wizards. I need a regular expression that will find groups of words. Any group of words. For instance, I'd like for it to find the first two words in any sentence.
Example "Hi there, how are you?" - Return would be "hi there"
Example "How are you doing?" - Return would be "How are"

Try this:
^\w+\s+\w+
Explanation: one or more word characters, spaces and more one or more word characters together.

Regular expressions could be used to parse language. Regular expressions are a more natural tool. After gathering the words, use a dictionary to see if they're actually words in a particular language.
The premise is to define a regular expression that will split out %99.9 of possible words, word being a key definition.
I assume C# is going to use a PCRE based on 5.8 Perl.
This is my ascii definition of how to split out words (expanded):
regex = '[\s[:punct:]]* (\w (?: \w | [[:punct:]](?=[\w[:punct:]]) )* )
and unicode (more has to be added/subtracted to suite specific encodings):
regex = '[\s\pP]* ([\pL\pN_-] (?: [\pL\pN_-] | \pP(?=[\pL\pN\pP_-]) )* )'
To find ALL of the words, cat the regex string into a regex (i don't know c#):
#matches =~ /$regex/xg
where /xg are the expanded and global modifiers. Note that there is only capture group 1 in the regex string so the intervening text is not captured.
To find just the FIRST TWO:
#matches =~ /(?:$regex)(?:$regex)/x
Below is a Perl sample. Anyway, play around with it. Cheers!
use strict;
use warnings;
binmode (STDOUT,':utf8');
# Unicode
my $regex = qr/ [\s\pP]* ([\pL\pN_-] (?: [\pL\pN_-] | \pP(?=[\pL\pN\pP_-]) )* ) /x;
# Ascii
# my $regex = qr/ [\s[:punct:]]* (\w (?: \w | [[:punct:]](?=[\w[:punct:]]) )* ) /x;
my $text = q(
I confirm that sufficient information and detail have been
reported in this technical report, that it's "scientifically" sound,
and that appropriate conclusion's have been included
);
print "\n**\n$text\n";
my #matches = $text =~ /$regex/g;
print "\nTotal ".scalar(#matches)." words\n",'-'x20,"\n";
for (#matches) {
print "$_\n";
}
# =======================================
my $junk = q(
Hi, there, A écafé and Horse d'oeuvre
hasn't? 'n? '? a-b? -'a-?
);
print "\n\n**\n$junk\n";
# First 2 words
#matches = $junk =~ /(?:$regex)(?:$regex)/;
print "\nFirst 2 words\n",'-'x20,"\n";
for (#matches) {
print "$_\n";
}
# All words
#matches = $junk =~ /$regex/g;
print "\nTotal ".scalar(#matches)." words\n",'-'x20,"\n";
for (#matches) {
print "$_\n";
}
Output:
**
I confirm that sufficient information and detail have been
reported in this technical report, that it's "scientifically" sound,
and that appropriate conclusion's have been included
Total 25 words
--------------------
I
confirm
that
sufficient
information
and
detail
have
been
reported
in
this
technical
report
that
it's
scientifically
sound
and
that
appropriate
conclusion's
have
been
included
**
Hi, there, A écafé and Horse d'oeuvre
hasn't? 'n? '? a-b? -'a-?
First 2 words
--------------------
Hi
there
Total 11 words
--------------------
Hi
there
A
écafé
and
Horse
d'oeuvre
hasn't
n
a-b
a-

#Rubens Farias:
Per my comment, here's the code I used:
public int startAt = 0;
private void btnGrabWordPairs_Click(object sender, EventArgs e)
{
Regex regex = new Regex(#"\b\w+\s+\w+\b"); //Start at word boundary, find one or more word chars, one or more whitespaces, one or more chars, end at word boundary
if (startAt <= txtTest.Text.Length)
{
string match = regex.Match(txtArticle.Text, startAt).ToString();
MessageBox.Show(match);
startAt += match.Length; //update the starting position to the end of the last match
}
{
Each time the button is clicked it grabs pairs of words quite nicely, proceeding through the text in the txtTest TextBox and finding the pairs sequentially until the end of the string is reached.
#sln: Thanks for the extremely detailed response!