Finding People and Things - Natural Language Processing with Java - page 142

Entity
type

Regular expression Output

ZIP
code

12345-1234
[150:160]

[0-9]{5}(\\-?[0-9]{4})?

E-
mail

[e-mail]
[27:45]

[a-zA-Z0-9'._%+-]+@(?:[a-zA-Z0-9-]+\\.)+[a-zA-Z]{2,4}

8:00 [217:221]

Time (([0-1]?[0-9])|([2][0-3])):([0-5]?[0-9])(:([0-5]?[0-9]))?

4:30 [229:233]

((0?[13578]|10|12)(-|\\/)(([1-9])|(0[1-9])|([12])([0-9]?)|(3[01]?))(-|\\/
)((19)([2-9])(\\d{1})|(20)([01])(\\d{1})|([8901])(\\d{1}))|(0?[2469]|11)(-
|\\/)(([1-9])|(0[1-9])|([12])([0-9]?)|(3[0]?))(-|\\/
)((19)([2-9])(\\d{1})|(20)([01])(\\d{1})|([8901])(\\d{1})))

2/25/1954
[315:324]

Date

There are many other regular expressions that we could have used. However, these ex-
amples illustrate the basic technique. As demonstrated with the date regular expression,
some of these can be quite complex.

It is common for regular expressions to miss some entities and to falsely report other non-
entities as entities. For example, if we replace the text with the following expression:

regularExpressionText =
"[phone] 888-SEL-HIGH 888-555-2222-J88-W3S";

Executing the code will return this:

888-555-2222 [27:39]

It missed the first two phone numbers and falsely reported the "part number" as a phone
number.

We can also search for more than one regular expression at a time using the | operator. In
the following statement, three regular expressions are combined using this operator. They
are declared using the corresponding entries in the previous table:

Pattern pattern = Pattern.compile(phoneNumberRE + "|"
+ timeRE + "|" + emailRegEx);