Jtdylktuy

I want to find and separate words in a title that has no spaces.

Before:

ThisIsAnExampleTitleHELLO-WORLD2019T.E.S.T.(Test)"Test"'Test'[Test]

After:

This Is An Example Title HELLO-WORLD 2019 T.E.S.T. (Test) [Test] "Test" 'Test'

I'm looking for a regular expression rule that can do the following.

I thought I'd identify each word if it starts with an uppercase letter.

But also preserve all uppercase words as not to space them into A L L U P P E R C A S E.

Additional rules:

• Space a letter if it touches a number: Hello2019World Hello 2019 World
  


• Ignore spacing initials that contain periods, hyphens, or underscores T.E.S.T.
  


• Ignore spacing if between brackets, parentheses, or quotes [Test] (Test) "Test" 'Test'
  


• Preserve hyphens Hello-World
  

C#

https://rextester.com/GAZJS38767

// Title without spaces

string title = "ThisIsAnExampleTitleHELLO-WORLD2019T.E.S.T.(Test)[Test]"Test"'Test'";



// Detect where to space words

string split =  Regex.Split(title, "(?<!^)(?=(?<![.\-'"([{])[A-Z][\d+]?)");



// Trim each word of extra spaces before joining

split = (from e in split

         select e.Trim()).ToArray();



// Join into new title

string newtitle = string.Join(" ", split);



// Display

Console.WriteLine(newtitle);

Regular expression

I'm having trouble with spacing before the numbers, brackets, parentheses, and quotes.

https://regex101.com/r/9IIYGX/1

(?<!^)(?=(?<![.-'"([{])(?<![A-Z])[A-Z][d+?]?)



(?<!^)          // Negative look behind



(?=             // Positive look ahead



(?<![.-'"([{]) // Ignore if starts with punctuation

(?<![A-Z])      // Ignore if starts with double Uppercase letter

[A-Z]           // Space after each Uppercase letter

[d+]?          // Space after number



)

Solution

Thanks for all your combined effort in answers. Here's a Regex example. I'm applying this to file names and have exclude special characters /:*?"<>|.

https://rextester.com/FYEVE73725

https://regex101.com/r/xi8L4z/1

First few parts are similar to @revo answer: (?<!^|[A-Zp{P}])[A-Z]|(?<=p{P})p{P}, additionally I add the following regex to space between number and letter: (?<=[a-z])(?=d)|(?<=d)(?=[a-z])|(?<=[A-Z])(?=d)|(?<=d)(?=[A-Z]) and to detect OTPIsADevice then replace with lookahead and lookbehind to find uppercase with a lowercase: (((?<!^)[A-Z](?=[a-z]))|((?<=[a-z])[A-Z]))

Note that | is or operator which allowed all the regex to be executed.

Regex: (?<!^|[A-Zp{P}])[A-Z]|(?<=p{P})p{P}|(?<=[a-z])(?=d)|(?<=d)(?=[a-z])|(?<=[A-Z])(?=d)|(?<=d)(?=[A-Z])|(((?<!^)[A-Z](?=[a-z]))|((?<=[a-z])[A-Z]))

Demo

Update

Improvised a bit:

From: (?<!^|[A-Zp{P}])[A-Z]|(?<=p{P})p{P}|(?<=[a-z])(?=d)|(?<=d)(?=[a-z])|(?<=[A-Z])(?=d)|(?<=d)(?=[A-Z])

into: (?<!^|[A-Zp{P}])[A-Z]|(?<=p{P})p{P}|(?<=p{L})d which do the same thing.

(((?<!^)(?<!p{P})[A-Z](?=[a-z]))|((?<=[a-z])[A-Z]))|(?<!^)(?=[[({&])|(?<=[)]}!&}]) improvised from OP comment which is adding exception to some punctuation: (((?<!^)(?<!['([{])[A-Z](?=[a-z]))|((?<=[a-z])[A-Z]))|(?<!^)(?=[[({&])|(?<=[)\]}!&}])

Final regex:
(?<!^|[A-Zp{P}])[A-Z]|(?<=p{P})p{P}|(?<=p{L})d|(((?<!^)(?<!p{P})[A-Z](?=[a-z]))|((?<=[a-z])[A-Z]))|(?<!^)(?=[[({&])|(?<=[)]}!&}])

Demo

Here is a regex which seems to work well, at least for your sample input:

(?<=[a-z])(?=[A-Z])|(?<=[0-9])(?=[A-Za-z])|(?<=[A-Za-z])(?=[0-9])|(?<=W)(?=W)

This patten says to make a split on a boundary of one of the following conditions:

• what precedes is a lowercase, and what precedes is an uppercase (or
  vice-versa)


• what precedes is a digit and what follows is a letter (or
  vice-versa)


• what precedes and what follows is a non word character
  (e.g. quote, parenthesis, etc.)

string title = "ThisIsAnExampleTitleHELLO-WORLD2019T.E.S.T.(Test)[Test]"Test"'Test'";

string split =  Regex.Split(title, "(?<=[a-z])(?=[A-Z])|(?<=[0-9])(?=[A-Za-z])|(?<=[A-Za-z])(?=[0-9])|(?<=\W)(?=\W)"); 

split = (from e in split select e.Trim()).ToArray();

string newtitle = string.Join(" ", split);



This Is An Example Title HELLO-WORLD 2019 T.E.S.T. (Test) [Test] "Test" 'Test'

Note: You might also want to add this assertion to the regex alternation:

(?<=W)(?=w)|(?<=w)(?=W)

We got away with this here, because this boundary condition never happened. But you might need it with other inputs.

Aiming for simplicity rather than huge regex, I would recommend this code with small simple patterns (comments with explanation are in code):

string str = "ThisIsAnExampleTitleHELLO-WORLD2019T.E.S.T.(Test)"Test"'Test'[Test]";

// insert space when there is small letter followed by upercase letter

str = Regex.Replace(str, "(?<=[a-z])(?=[A-Z])", " ");

// insert space whenever there's digit followed by a ltter

str = Regex.Replace(str, @"(?<=d)(?=[A-Za-z])", " ");

// insert space when there's letter followed by digit

str = Regex.Replace(str, @"(?<=[A-Za-z])(?=d)", " ");

// insert space when there's one of characters ("'[ followed by letter or digit

str = Regex.Replace(str, @"(?=[([""'][a-zA-Z0-9])", " ");

// insert space when what preceeds is on of characters ])"'

str = Regex.Replace(str, @"(?<=[)]""'])", " ");

You could reduce the requirements to shorten the steps of a regular expression using a different interpretation of them. For example, the first requirement would be the same as to say, preserve capital letters if they are not preceded by punctuation marks or capital letters.

The following regex works almost for all of the mentioned requirements and may be extended to include or exclude other situations:

(?<!^|[A-Zp{P}])[A-Z]|(?<=p{P})p{P}

You have to use Replace() method and use $0 as substitution string.

See live demo here

.NET (See it in action):

string input = @"ThisIsAnExample.TitleHELLO-WORLD2019T.E.S.T.(Test)""Test""'Test'[Test]";

Regex regex = new Regex(@"(?<!^|[A-Zp{P}])[A-Z]|(?<=p{P})p{P}", RegexOptions.Multiline);

Console.WriteLine(regex.Replace(input, @" $0"));