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Regular Expressions

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18_Day_Regular_expressions/18_regular_expressions.md
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@ -38,7 +38,6 @@
- [Cart ^](#cart-)
- [💻 Exercises: Day 18](#-exercises-day-18)
# 📘 Day 18
## Regular Expressions
@ -56,6 +55,7 @@ import re
### Functions in *re* Module
To find a pattern we use different set of *re* character sets that allows to search for a match in a string.
* *re.match()*: searches only in the beginning of the first line of the string and returns matched objects if found, else returns none.
* *re.search*: Returns a match object if there is one anywhere in the string, including multiline strings.
* *re.findall*: Returns a list containing all matches
@ -96,6 +96,7 @@ As you can see from the example above, the pattern we are looking for (or the su
re.match(substring, string, re.I)
# substring is a pattern, string is the text we look for a pattern , re.I is case ignore flag
```
```py
import re
@ -184,6 +185,7 @@ D%o%es thi%s m%ot%iv%a%te %y%o%u to b%e a t%e%a%cher?'''
matches = re.sub('%', '', txt)
print(matches)
```
```sh
I am teacher and I love teaching.
There is nothing as rewarding as educating and empowering people.
@ -200,6 +202,7 @@ I found teaching more interesting than any other jobs.
Does this motivate you to be a teacher?'''
print(re.split('\n', txt)) # splitting using \n - end of line symbol
```
```sh
['I am teacher and I love teaching.', 'There is nothing as rewarding as educating and empowering people.', 'I found teaching more interesting than any other jobs.', 'Does this motivate you to be a teacher?']
```
@ -300,6 +303,7 @@ print(matches) # ['6', '2019'] - now, this is better!
```
### Period(.)
```py
regex_pattern = r'[a].' # this square bracket means a and . means any character except new line
txt = '''Apple and banana are fruits'''
@ -309,7 +313,6 @@ print(matches) # ['an', 'an', 'an', 'a ', 'ar']
regex_pattern = r'[a].+' # . any character, + any character one or more times
matches = re.findall(regex_pattern, txt)
print(matches) # ['and banana are fruits']
```
### Zero or more times(\*)
@ -317,12 +320,10 @@ print(matches) # ['and banana are fruits']
Zero or many times. The pattern could may not occur or it can occur many times.
```py
regex_pattern = r'[a].*' # . any character, * any character zero or more times
txt = '''Apple and banana are fruits'''
matches = re.findall(regex_pattern, txt)
print(matches) # ['and banana are fruits']
```
### Zero or one time(?)
@ -335,7 +336,6 @@ Some people write it email others may write it as Email or E-mail.'''
regex_pattern = r'[Ee]-?mail' # ? means here that '-' is optional
matches = re.findall(regex_pattern, txt)
print(matches) # ['e-mail', 'email', 'Email', 'E-mail']
```
### Quantifier in RegEx
@ -352,7 +352,6 @@ txt = 'This regular expression example was made on December 6, 2019.'
regex_pattern = r'\d{1, 4}' # 1 to 4
matches = re.findall(regex_pattern, txt)
print(matches) # ['6', '2019']
```
### Cart ^
@ -381,6 +380,7 @@ print(matches) # ['6,', '2019.']
```py
paragraph = 'I love teaching. If you do not love teaching what else can you love. I love Python if you do not love something which can give you all the capabilities to develop an application what else can you love.
```
```sh
[(6, 'love'),
(5, 'you'),