Identifiers.md

Identifiers

You can use different identifiers with modifiers to achieve different pattern searching.

1.Numbers

\d Any Number

\D Anything except Number

• matches number 0,1,2,3,4,5,6,7,8,9

Syntax:

pattern='\d'

Example:

import re
input_string='today date is 21 feb 2019'

#Read Numbers
pattern=r'\d'
result=re.findall(pattern,input_string)
print("Print Numbers")
print(result)
#Result:['2', '1', '2', '0', '1', '9']


#Find Numbers in groupusing + modifiers
pattern=r'\d+'
result=re.findall(pattern,input_string)
print("\n Print Grouped NUmbers Using Modifiers")
print(result)
#Result:['21', '2019']


#Find out 2 digit number
pattern=r'\d{2}'
result=re.findall(pattern,input_string)
print("\nFind 2 Digit Numbers")
print(result)
#Result:['21', '20', '19']

#Find out all text without number
pattern=r'\D'
result=re.findall(pattern,input_string)
print("\nFind out all text without number")
print(result)

#Find a any number followed by 2 and number should be 3 digit
pattern=r'2[\d]{2}'
result=re.findall(pattern,input_string)
print("\nfollowed by 2 and number should be 3 digit")
print(result)
#Result:['201']


#Find Numbers in groupusing * modifiers
pattern=r'\d*'
result=re.findall(pattern,input_string)
print("\nNumbers in groupusing * modifiers")
print(result)

Output:

Print Numbers
['2', '1', '2', '0', '1', '9']

 Print Grouped NUmbers Using Modifiers
['21', '2019']

Find 2 Digit Numbers
['21', '20', '19']

Find out all text without number
['t', 'o', 'd', 'a', 'y', ' ', 'd', 'a', 't', 'e', ' ', 'i', 's', ' ', ' ', 'f', 'e', 'b', ' ']

followed by 2 and number should be 3 digit
['201']

Numbers in groupusing * modifiers
['', '', '', '', '', '', '', '', '', '', '', '', '', '', '21', '', '', '', '', '', '2019', '']

2.Strings

\w matches with alphabets and numbers only

a,b,c...z A,B,C.....Z,0,1,2,3,4,5,6,7,8,9

\W anything without a string

Example:

import re

input_string='Hi @ gmail 12'

#Find normal string characters
pattern=r'\w'
result=re.findall(pattern,input_string)
print("Find normal string characters")
print(result)
#Result:['H', 'i', 'g', 'm', 'a', 'i', 'l', '1', '2']



#Find normal string characters with grouping modifiers
pattern=r'\w+'
result=re.findall(pattern,input_string)
print("\nnormal string characters with grouping modifiers")
print(result)
#Result:['Hi', 'gmail', '12']


#Findout 2 length character string
pattern=r'\w{2}'
result=re.findall(pattern,input_string)
print("\n2 Length Strings")
print(result)
#Result:['Hi', 'gmail', '12']


#Check input string starting with Hi
pattern=r'^Hi'
print("\n input string starting with Hi")
result=re.findall(pattern,input_string)
print(result)
#Result:['Hi']

Output:

Find normal string characters
['H', 'i', 'g', 'm', 'a', 'i', 'l', '1', '2']

normal string characters with grouping modifiers
['Hi', 'gmail', '12']

2 Length Strings
['Hi', 'gm', 'ai', '12']

 input string starting with Hi
['Hi']

3.Anything (but not newline character)

.

• .(dot) is used to achieve create a pattern that results in any character but except a new line.
• This will match anything but not a new line

Example:

import re

input_string='This is simple example, \n contains three lines \n @$# 4555'

#using + modifiers This doesn't match new line character that is /n
pattern=r'.+'
result=re.findall(pattern,input_string)
print(result)

Output:

['This is simple example, ', ' contains three lines ', ' @$# 4555']

4.Space

\s space

\S anything Except Space

• matches A whitespace character

A whitespace character can be:

• A space character
  • A tab character
  • A carriage return character
  • A new line character
  • A vertical tab character
  • A form feed character

Example:

import re

input_string=' This is simple example'

#get no of spaces in input string
pattern=r'\s'
result=re.findall(pattern,input_string)
print("Get no of spaces in input string")
print(result)
#Result: [' ', ' ', ' ']

#return all text except space characters
pattern=r'\S+'
result=re.findall(pattern,input_string)
print("\nall text except space characters")
print(result)
#Result: ['This', 'is', 'simple', 'example']

Output:

Get no of spaces in input string
[' ', ' ', ' ']

all text except space characters
['This', 'is', 'simple', 'example']