notepad++ regular expression learn

 https://www.linguisticsweb.org/doku.php?id=linguisticsweb:tutorials:basics:regex:regex-notepad

Terminology	Definition
Character	A single letter, digit, punctuation marker, whitespace, etc.
Whitespace	Any character that is not visible: space, tab, etc.
String	Any sequence of characters.
Operator	Characters with special meaning in a particular context.

RegEx	Effect	Example
a	Find character ‘a’
abc	Find string abc
[…]	Find any of ‘…’	[abc] finds characters ‘a’, ‘b’, or ‘c’
[a-z]	Find any in the range from ‘a’ to ‘z’	[a-f] finds any of the lowercase letters ‘a’ to ‘f’
[^x]	Find anything that is not ‘x’	[^aeiou] Finds all characters that are not vowels, including punctuation, digits and whitespace
?	The previous element is optional, it does not have to occur	[1-9][0-9]? Finds numbers from 1 to 9 and 10 to 99
.	Find any character except newline, linefeed, carriage return
+	Find the previous element 1 to many times	r+ finds ‘r’, rr, rrr, rrrr, etc.
*	Find the previous element 0 to many times	[a-zA-Z]*ed finds strings ending in ed
{x,y}	Repeat the previous element x to y times	[0-9]{5,7} Finds any sequence of 5 to 7 digits.
(…)	Save anything inside the parentheses for use in replacement	(store this) finds and stores the string store this
\1 \2 \3	Restore the string saved by the parentheses, for use in replacement	\1ing adds ing to the saved string
\w	Shortcut for word characters (letters, digits and underscores)	\w* finds cat, dog, login_name, cutie17, etc.
\d	Shortcut for digits, same as [1-9]
\b	Marks the beginning or end of a word
\	Escape the operator following ‘\’	\[\w*\] finds a word in brackets

Some examples

Counting part of speech tags

regex pattern	example hit
'NN.'	finds all instances of plural and proper noun tags: NNP, NNS
'NN'	finds all instances of singular noun tags: NN