1. LING 408/508: Computational Techniques for Linguists
Lecture 18

2. Adminstrivia
Reminder: no class next Tuesday (out of meeting)

3. Today's Topics Homework 6 graded Part 2: Homework 6 review Last time:

4. Homework 6 Review Javascript functions: Term project idea:
shuffle() solved()
Term project idea:
animate solution
16!/2 = 10,461,394,944,000 valid configurations
i.e. write a function solve()
ss.com/2008/01/27/puzzles- groups-and-groupoids/
Stage 1: put 1 and 2 into position, get 3 and 4 into the corner
Stage 2: repeat for 5-8
Stage 3: put 9 and 13 into position
Stage 4: solve rest of the pieces

5. Javascript regular expressions
Let's write our own browser-based tester to help you learn regular expressions:
form
See:

6. Javascript regular expressions
<input name=str>
<input name=g>
<input name=re>

7. Javascript regular expressions
optional
What Javascript provides:
RegEx object
var re = new RegEx(string, flags)
var re = /[A-Z]([a-z])*/gi (g= global; i=ignore case)
Methods:
var a = string.match(re) returns an array
[entire match, ...submatches…]
var a = regex.exec(string) returns an array
different behaviors (under global flag)

8. Javascript Regexp Tester
Let's try the code:
Mr. ([A-Z][a-z]*)
Mr\. ([A-Z][a-z]*)

9. Javascript Regexp Tester
Useful property
regex.lastIndex

10. Regular expression syntax

11. Regular expression syntax

12. Regular expression syntax

13. Regular expression syntax

14. Regular expression syntax

15. Regex Replace We'll also need the method replace():
var regex = new RegExp(re_s,flag_s);
modified_string = string.replace(regex,replacement)
replacement string can contain $n (NOT \n)
(n = group number)
developer.mozilla.org

16. Regex Replace Let's try it out: