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RegEx Regular Expression Link WEB - Coggle Diagram

RegEx
Regular Expression
Link WEB

Metacharacters
Characters with
special meaning

[ ]: A set of character

- Example

#Find all lower case character alphabet between 'a' and 'm'
txt = "The rain in Spain"
x = re.findall("[a-m]", txt
print(x)

- Result

['h', 'e', 'a', 'i', 'i', 'a', 'i']

\ : Signal a special sequence
(can also be used to escape special character)

- Example

# Find all digit charactersx
txt = "That will be 59 dollars"
x = re.findall("\d", txt)
print(x)

- Result

['5', '9']

. : Any character
(except newline character)

- Example

# Search for a sequence that starts with "he", followed by two (any) characters and an "o"
txt = "hello planet"
x = re.findall("he..o", txt)
print(x)

- Result

['hello']

^ : Start with

- Example

# Check if the string starts with 'hello'
txt = "hello planet"
x = re.findall("^hello", txt)
if x:
    print("Yes, the string starts with 'hello'")
else
    print(No match)

- Result

Yes, the string starts with 'hello

$ : End with

- Example

# Check if the string end with 'planet'
txt = "hello planet"
x = re.findall("planet$", txt)  --> return True/False
if x:
    print("Yes, the string starts with 'hello'")
else
    print(No match)

- Result

Yes, the string starts with 'hello

* : Zero or more occurrences
(lần xuất hiện)

- Example

# Search for a sequence that starts with "he", followed by 0 or more (any) characters and an "o"
txt = "hello planet"
x = re.findall("he.*o", txt)
print(x)

- Result

['hello']

+ : One or more occurrences
(lần xuất hiện)

- Example

# Search for a sequence that starts with "he", followed by 1 or more (any) characters and an "o"
txt = "hello planet"
x = re.findall("he.+o", txt)
print(x)

- Result

['hello']

- 2 more items...

Special Sequence
A special sequence is a \ followed by one of character in the list, has a special meaning

\A : Return a match if the specified character are at the begining of string

- Example

# Check if the string start with "The"
txt = "The rain in Spain"
x = re.findall("\AThe", txt)
print (x)
if x:
    print("Yes, there is a match!")
else:
    print("No match")

- Result

['The']
Yes, there is a match!

\b : Return a match where the specified character are at the beginning or at the end of a word
The "r" in the beginning is making sure that the string is being treated as a "raw string"

- Example

# Check if 'ain' is present at the beginning of a WORD:"
txt = "The rain in Spain"
x = re.findall(r"\bain", txt)
print (x)
if x:
    print("Yes, there is at least one match!")
else:
    print("No match")

- Result

[]
No match!

- Example

# Check if 'ain' is present at the endof a WORD:"
txt = "The rain in Spain"
x = re.findall(r"ain\b", txt)
print (x)
if x:
    print("Yes, there is at least one match!")
else:
    print("No match")

- Result

['ain', 'ain']
Yes, there is at least one match!

\B : Return a match where the specified character are present, but NOT at the beginning or at the end of a word
The "r" in the beginning is making sure that the string is being treated as a "raw string"

- Example

# Check if 'ain' is present, but NOT at the beginning of a WORD:"
txt = "The rain in Spain"
x = re.findall(r"\Bain", txt)
print (x)
if x:
    print("Yes, there is at least one match!")
else:
    print("No match")

- Result

['ain', 'ain']
Yes, there is at least one match!

- Example

# Check if 'ain' is present, but not at the endof a WORD:"
txt = "The rain in Spain"
x = re.findall(r"ain\B", txt)
print (x)
if x:
    print("Yes, there is at least one match!")
else:
    print("No match")

- Result

[]
No match!

\d : Return a match where the string contains digits (number from 0-9)

- Example

# Check if the stringcontain any digits ( number from 0-9)
txt = "The rain in Spain"
x = re.findall("\d", txt)
print (x)
if x:
    print("Yes, there is at least one match!")
else:
    print("No match")

- Result

[]
No match

\D : Return a match where the string DOES NOT contains digits (number from 0-9)

- Example

# Check if the string DOES NOT contain any digits ( number from 0-9)
txt = "The rain in Spain"
x = re.findall("\D", txt)
print (x)
if x:
    print("Yes, there is at least one match!")
else:
    print("No match")

- Result

['T', 'h', 'e', ' ', 'r', 'a', 'i', 'n', ' ', 'i', 'n', ' ', 'S', 'p', 'a', 'i', 'n']
Yes, there is at least one match!

\s : Return a match where the string contains a white space charcter

- Example

#Return a match at every white-space character
txt = "The rain in Spain"
x = re.findall("\s", txt)
print (x)
if x:
    print("Yes, there is at least one match!")
else:
    print("No match")

- Result

[' ', ' ', ' ']
Yes, there is at least one match!

\S : Return a match where the string DOES NOT contains a white space charcter

- Example

#Return a match at every NON white-space character
txt = "The rain in Spain"
x = re.findall("\S", txt)
print (x)
if x:
    print("Yes, there is at least one match!")
else:
    print("No match")

- Result

['T', 'h', 'e', 'r', 'a', 'i', 'n', 'i', 'n', 'S', 'p', 'a', 'i', 'n']
Yes, there is at least one match!

- 2 more items...

SET
A set of character inside a pair of square brackets [ ]

[arn]: Return a match where one of the specified characters (a, r, or n) is present

- Example

#Check if the string has any a, r, or n characters:
txt = "The rain in Spain"
x = re.findall("[arn]", txt)
print(x)
if x:
    print("Yes, there is at least one match!")
else:
    print("No match")

- Result

['r', 'a', 'n', 'n', 'a', 'n']
Yes, there is at least one match!

[a-n]: Returns a match for any lower case character, alphabetically between a and n

- Example

#Check if the string has any characters between a and n:
txt = "The rain in Spain"
x = re.findall("[a-n]", txt)
print(x)
if x:
    print("Yes, there is at least one match!")
else:
    print("No match")

- Result

['h', 'e', 'a', 'i', 'n', 'i', 'n', 'a', 'i', 'n']
Yes, there is at least one match!

[^arn]: Returns any match for any character EXCEPT (a, r or n)

- Example

#Check if the string has other characters than a, r, or n:
txt = "The rain in Spain"
x = re.findall("[^arn]", txt)
print(x)
if x:
    print("Yes, there is at least one match!")
else:
    print("No match")

- Result

['T', 'h', 'e', ' ', 'i', ' ', 'i', ' ', 'S', 'p', 'i']
Yes, there is at least one match!

[0123]: Returns a match where any of the specified digits (0, 1, 2, or 3) are present

- Example

#Check if the string has any 0, 1, 2, or 3 digits:
txt = "The rain in Spain 1356"
x = re.findall("[0123]", txt)
print(x)
if x:
    print("Yes, there is at least one match!")
else:
    print("No match")

- Result

['1', '3']
Yes, there is at least one match!

[0-9]: Returns a match for any digit between 0 and 9**

- Example

#Check if the string has any digits:
txt = "8 times before 11:45 AM"
x = re.findall("[0-9]", txt)
print(x)
if x:
    print("Yes, there is at least one match!")
else:
    print("No match")

- Result

['8', '1', '1', '4', '5']
Yes, there is at least one match!

[0-5][0-9]: Returns a match for any two-digit numbers from 00 and 59

- Example

#Check if the string has any two-digit numbers, from 00 to 59:
txt = "8 times before 11:45 AM"
x = re.findall("[0-5][0-9]", txt)
print(x)
if x:
    print("Yes, there is at least one match!")
else:
    print("No match")

- Result

['11', '45']
Yes, there is at least one match!

[a-zA-Z]: Returns a match for any character alphabetically between a and z, lower case OR upper case

- Example

#Check if the string has any characters from a to z lower case, and A to Z upper case:
txt = "8 times before 11:45 AM"
x = re.findall("[a-zA-Z]", txt)
print(x)
if x:
    print("Yes, there is at least one match!")
else:
    print("No match")

- Result

['t', 'i', 'm', 'e', 's', 'b', 'e', 'f', 'o', 'r', 'e', 'A', 'M']
Yes, there is at least one match!

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