Develop Reference

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'

Removal of colon and carriage returns and replace with colon

I'm working on a project where I have a HMTL fragment which needs to be cleaned up - the HTML has been removed and as a result of table being removed, there are some strange ends where they shouldnt be :-)
the characters as they appear are
a space at the beginning of a line
a colon, carriage return and linefeed at the end of the line - which needs to be replaced simply with the colon;
I am presently using regex as follows:
s = Regex.Replace(s, #"(:[\r\n])", ":", RegexOptions.Multiline | RegexOptions.IgnoreCase);
// gets rid of the leading space
s = Regex.Replace(s, #"(^[( )])", "", RegexOptions.Multiline | RegexOptions.IgnoreCase);
Example of what I am dealing with:
Tomas Adams
Solicitor
APLawyers
p:
1800 995 718
f:
07 3102 9135
a:
22 Fultam Street
PO Box 132, Booboobawah QLD 4113
which should look like:
Tomas Adams
Solicitor
APLawyers
p:1800 995 718
f:07 3102 9135
a:22 Fultam Street
PO Box 132, Booboobawah QLD 4313
as my attempt to clean the string, but the result is far from perfect ... Can someone assist me to correct the error and achive my goal ...
[EDIT]
the offending characters
f:\r\n07 3102 9135\r\na:\r\n22
the combination of :\r\n should be replaced by a single colon.
MTIA
Darrin

You may use
var result = Regex.Replace(s, #"(?m)^\s+|(?<=:)(?:\r?\n)+|(\r?\n){2,}", "$1")
See the .NET regex demo.
Details
(?m) - equal to RegexOptions.Multiline - makes ^ match the start of any line here
^ - start of a line
\s+ - 1+ whitespaces
| - or
(?<=:)(?:\r?\n)+ - a position that is immediately preceded with : (matched with (?<=:) positive lookbehind) followed with 1+ occurrences of an optional CR and LF (those are removed)
| - or
(\r?\n){2,} - two or more consecutive occurrences of an optional CR followed with an LF symbol. Only the last occurrence is saved in Group 1 memory buffer, thus the $1 replacement pattern inserts that last, single, occurrence.

A basic solution without Regex:
var lines = input.Split(new []{"\n"}, StringSplitOptions.RemoveEmptyEntries);
var output = new StringBuilder();
for (var i = 0; i < lines.Length; i++)
{
if (lines[i].EndsWith(":")) // feel free to also check for the size
{
lines[i + 1] = lines[i] + lines[i + 1];
continue;
}
output.AppendLine(lines[i].Trim()); // remove space before or after a line
}
Try it Online!

I tried to use your regular expression.I was able to replace "\n" and ":" with the following regular expression.This is removing ":" and "\n" at the end of the line.
#"([:\r\n])"

A Linq solution without Regex:
var tmp = string.Empty;
var output = input.Split(new []{"\n"}, StringSplitOptions.RemoveEmptyEntries).Aggregate(new StringBuilder(), (a,b) => {
if (b.EndsWith(":")) { // feel free to also check for the size
tmp = b;
}
else {
a.AppendLine((tmp + b).Trim()); // remove space before or after a line
tmp = string.Empty;
}
return a;
});
Try it Online!

How to extract address components from a string?

I have a Xamarin Forms application that uses Xamarin. Mobile on the platforms to get the current location and then ascertain the current address. The address is returned in string format with line breaks.
The address can look like this:
111 Mandurah Tce
Mandurah WA 6210
Australia
or
The Glades
222 Mandurah Tce
Mandurah WA 6210
Australia
I have this code to break it down into the street address (including number), suburb, state and postcode (not very elegant, but it works)
string[] lines = address.Split(new string[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries);
List<string> addyList = new List<string>(lines);
int count = addyList.Count;
string lineToSplit = addyList.ElementAt(count - 2);
string[] splitLine = lineToSplit.Split(null);
List<string> splitList = new List<string>(splitLine);
string streetAddress = addyList.ElementAt (count - 3).ToString ();
string postCode = splitList.ElementAt(2);
string state = splitList.ElementAt(1);
string suburb = splitList.ElementAt(0);
I would like to extract the street number, and in the previous examples this would be easy, but what is the best way to do it, taking into account the number might be Lot 111 (only need to capture the 111, not the word LOT), or 123A or 8/123 - and sometimes something like 111-113 is also returned
I know that I can use regex and look for every possible combo, but is there an elegant built-in type solution, before I go writing any more messy code (and I know that the above code isn't particularly robust)?

These simple regular expressions will account for many types of address formats, but have you considered all the possible variations, such as:
PO Box 123 suburb state post_code
Unit, Apt, Flat, Villa, Shop X Y street name
7C/94 ALISON ROAD RANDWICK NSW 2031
and that is just to get the number. You will also have to deal with all the possible types of streets such as Lane, Road, Place, Av, Parkway.
Then there are street types such as:
12 Grand Ridge Road suburb_name
This could be interpreted as street = "Grand Ridge" and suburb = "Road suburb_name", as Ridge is also a valid street type.
I have done a lot of work in this area and found the huge number of valid address patterns meant simple regexs didn't solve the problem on large amounts of data.
I ended up develpping this parser http://search.cpan.org/~kimryan/Lingua-EN-AddressParse-1.20/lib/Lingua/EN/AddressParse.pm to solve the problem. It was originally written for Australian addresses so should work well for you.

Regex can capture the parts of a match into groups. Each parentheses () defines a group.
([^\d]*)(\d*)(.*)
For "Lot 222 Mandurah Tce" this returns the following groups
Group 0: "Lot 222 Mandurah Tce" (the input string)
Group 1: "Lot "
Group 2: "222"
Group 3: " Mandurah Tce"
Explanation:
[^\d]* Any number (including 0) of any character except digits.
\d* Any number (including 0) of digits.
.* Any number (including 0) of any character.
string input = "Lot 222 Mandurah Tce";
Match match = Regex.Match(input, #"([^\d]*)(\d*)(.*)");
string beforeNumber = match.Groups[1].Value; // --> "Lot "
string number = match.Groups[2].Value; // --> "222"
string afterNumber = match.Groups[3].Value; // --> " Mandurah Tce"
If a group finds no match, match.Groups[i] will return an empty string ("") for that group.

You could check if the content starts with a number for each entry in the splitLine.
string[] splitLine = lineToSplit.Split(addresseLine);
var streetNumber = string.empty;
foreach(var s in splitLine)
{
//Get the first digit value
if (Regex.IsMatch(s, #"^\d"))
{
streetNumber = s;
break;
}
}
//Deal with empty value another way
Console.WriteLine("My streetnumber is " + s)

Yea I think you have to identify what will work.
If:
it is always in the address line and it must always start with a Digit
nothing else in that line can start with a digit (or if something else does you know which always comes in what order, ie the code below will always work if the street number is always first)
you want every contiguous character to the digit that isn't whitespace (the - and \ examples suggest that to me)
Then it could be as simple as:
var regx = new Regex(#"(?:\s|^)\d[^\s]*");
var mtch = reg.Match(addressline);
You would sort of have to sift and see if any of those assumptions are broken.

checking input for morse code converter

I want to check the input from the user to make sure that they only enter dots and dashes and any other letters or numbers will give back and error message. Also i wanted to allow the user to enter a space yet when i am converting how can i remove or ignore the white space?
string permutations;
string entered = "";
do
{
Console.WriteLine("Enter Morse Code: \n");
permutations = Console.ReadLine();
.
.
} while(entered.Length != 0);
Thanks!

string permutations = string.Empty;
Console.WriteLine("Enter Morse Code: \n");
permutations = Console.ReadLine(); // read the console
bool isValid = Regex.IsMatch(permutations, #"^[-. ]+$"); // true if it only contains whitespaces, dots or dashes
if (isValid) //if input is proper
{
permutations = permutations.Replace(" ",""); //remove whitespace from string
}
else //input is not proper
{
Console.WriteLine("Error: Only dot, dashes and spaces are allowed. \n"); //display error
}

Let's assume that you separate letters by a single space and words by two spaces. Then you can test if your string is well formatted by using a regular expression like this
bool ok = Regex.IsMatch(entered, #"^(\.|-)+(\ {1,2}(\.|-)+)*$");
Regular expression explained:
^ is the beginning of the string.
\.|- is a dot (escaped with \ as the dot has a special meaning within Regex) or (|) a minus sign.
+ means one or more repetitions of what's left to it (dot or minus).
\ {1,2} one or two spaces (they are followed by dots or minuses again (\.|-)+).
* repeats the space(s) followed by dots or minuses zero or more times.
$ is the end of the line.
You can split the string at the spaces with
string[] parts = input.Split();
Two spaces will create an empty entry. This allows you to detect word boundaries. E.g.
"–– ––– .–. ... . –.–. ––– –.. .".Split();
produces the following string array
{string[10]}
[0]: "––"
[1]: "–––"
[2]: ".–."
[3]: "..."
[4]: "."
[5]: ""
[6]: "–.–."
[7]: "–––"
[8]: "–.."
[9]: "."

Math expression on Regex expression

I have many text rows, and I must find some rows, and to change them.
I wrote such regex rule:
^(Position) ([0-9]+)$
For example, I must find all such rows:
Position 10
Position 11
Position 12
Now I must increase numbers at 5. How can I do it through Regex?
I try to wrote such regex rule:
$1 {$2+ 5}
I need get result:
Position 15
Position 16
Position 17
But I have got:
Position {10 +5}
Position {11+5}
Position {12+5}

the Regex Replace function takes either a string, or a function. you used the string replacement, so just the string is inserted. if you want an integer operation, you need to use the replace with function method.
http://msdn.microsoft.com/library/cft8645c(v=vs.80).aspx
this code is not correct, it should just show the way how it could be done
Regex.Replace("^(Position) ([0-9]+)$", ReplaceFunction);
public string ReplaceFunction(Match m) { return "Position " + (int.Parse(m.Groups[2].Value) + 5); };

string input = #"Position 10";
string output = Regex.Replace(input, "^Position ([0-9]+)$", match => "Position " + Int32.Parse(match.Groups[1].Value) + 5);