Regular Expressions are used to find out a sequence of characters that define a search pattern. This repository contains artifacts to extract the valid email, url, US phone number, currency, UK postal code, US zipcode and date formats from the given input text file.

The python script Regex.py contains the regular expression validations which when applied to the given input file will extract the valid patterns.

Run the python script by passing in the command line input arguments as below:

Regex.py input_file_name [arguments]
where Regex.py is the name of the python script file (provided)
input_file_name - the input text file from where the text matching the patterns has to be extracted from
[arguments] - specify one or more of the following arguments
-e extracts all the valid email occurrences
-u extracts all the valid url occurrences
-c extracts all the currency value (USD, EUR, CAN) occurrences
-p extracts all the US phone number occurrences
-k extracts all the UK postal code occurrences
-d extracts all the date occurrences
-z extracts all the US zipcode occurrences

Here are the various formats supported for different types.

Note: The regular expressions used in the python script have a trailing space at the end when compared with the expressions provided here in the readme. The trailing space in the expression(s) is needed for python script so as to extract the words from a sentence. Also, for US Zipcode, additionally the dollar($) symbol is needed for the python script to extract the words from a sentence.

Regular Expression:
[a-zA-Z0-9][a-zA-Z0-9!#$%&\'*+/=.?^_`{|}~-]*@(?:[a-zA-Z](?:[a-zA-Z0-9-]*)?\.)+[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z])?

The email addresses are generally in the form local-part@domain.

The local-part of the email address may use any of these ASCII characters:

1. Uppercase and lowercase letters A to Z and a to z
2. Digits 0 to 9
3. Printable characters !#$%&'*+-/=?^_`{|}~

The domain could be in the following formats:

1. Uppercase and lowercase letters A to Z and a to z
2. Digits 0 to 9, provided that top-level domain names are not all-numeric
3. Hyphen - provided that it is not the first or last character

Ref: https://en.wikipedia.org/wiki/Email_address

Regular Expression:
http[s]?://(?:[a-zA-Z0-9$-_@.&+!*\(\),]|(?:%[0-9a-zA-Z]))+

A typical URL could have the form http://www.example.com/index.html, which indicates a protocol (http), a hostname (www.example.com), and a file name (index.html). The regular expression is intended to match URL that starts with either http or https.
Ref: https://en.wikipedia.org/wiki/URL

Regular Expression:
[+]?[1\s-]*[\(-]?[0-9]{3}[-\)]?[\s-]?[0-9]{3}[\s-]?[0-9]{4}

The regular expression recognises the US phone number formats in the below patterns:

• (###) ###-####
• +(#)(###) ###-####
• (#)(###) ###-####

Ref: https://en.wikipedia.org/wiki/National_conventions_for_writing_telephone_numbers#North_America

Regular Expression:
(?:\$|can\$|C\$|€|USD|CAD|EUR|ATS|BEF|DEM|EEK|ESP|FIM|FRF|GRD|IEP|ITL|LUF|NLG|PTE|can)[\s\S]?\d{1,3}(?:,\d{3})*(?:\.\d{1,3})?

The regular expression validates only US Dollar (USD), Euro (EUR) and Canadian Dollar (CAD) currency formats as below: Considered the following currency symbols

• US currency format starting with $ symbol.
• Canadian currency formats starting with can$, CAD, can, C$ symbols.
• Euro currency formats starting with EUR, ATS, BEF, DEM, EEK, ESP, FIM, FRF, GRD, IEP, ITL, LUF, NLG, PTE, € symbols.

Regular Expression:
[A-Z]{1,2}[0-9R][0-9A-Z]? [0-9][ABD-HJLNP-UW-Z]{2}

UK Postal code format is as follows, where A signifies a letter and 9 a digit:

Ref: https://en.wikipedia.org/wiki/Postcodes_in_the_United_Kingdom

Regular Expression:
[0-9]{5}(-[0-9]{4})?

The regular expression matches US Zipcode that includes nine digits in the format ddddd-dddd Ref: https://en.wikipedia.org/wiki/List_of_postal_codes

The regular expression validates the dates that appear in the following formats

Regular Expressions:
dd/mm/yyyy - \s?(?:0?[1-9]|[1,2][0-9]|3[0-1])(?:/)(?:0?[1-9]|1[0-2])(?:/)(?:\d{4})

mm/dd/yyyy - \s?(?:0?[1-9]|1[0-2])(?:/)(?:0?[1-9]|[1,2][0-9]|3[0-1])(?:/)(?:\d{4})

1st mon/month yyyy - \s?(?:0?[1-9]|[1,2][0-9]|3[0-1])(?:nd|rd|th|st)?(?:[\s|,|]?\s?)(?:[Jj]an(?:uary)?|[Ff]eb(?:ruary)?|[Mm]ar(?:ch)?|[Aa]pr(?:il)?|[Mm]ay|[Jj]une|[Jj]uly|[Aa]ug(?:ust)?|[Ss]ept(?:ember)?|[Oo]ct(?:ober)?|[Nn]ov(?:ember)?|[Dd]ec(?:ember)?)\s\d{4}

mon/month, 1, yyyy - \s?(?:[Jj]an(?:uary)?|[Ff]eb(?:ruary)?|[Mm]ar(?:ch)?|[Aa]pr(?:il)?|[Mm]ay|[Jj]une|[Jj]uly|[Aa]ug(?:ust)?|[Ss]ept(?:ember)?|[Oo]ct(?:ober)?|[Nn]ov(?:ember)?|[Dd]ec(?:ember)?)(?:[\s|,]?\s?)(?:0?[1-9]|[1,2][0-9]|3[0-1])(?:[\s|,]?\s?)\s\d{4}

Note - The above specified date format Regular Expression patterns works individually and also can be merged with pipe symbol to make it as single Regular Expression for ease of use.