Regular Expressions for Regular Joes (and SEOs)

Regular Expressions
for Regular Joes
(and SEOs)

What are regular expressions?
• A regular expression (sometimes referred to as
regex or regexp) is basically find-and-replace
on steroids, an advanced system of matching
text patterns.
COPYRIGHT 2014 CATALYST. ALL RIGHTS RESERVED. APRIL 29, 2014 | PAGE 2

Most Common Example: Google Analytics
• Using “pipes” to exclude pages with extraneous
symbols attached to the URL, like UTM tracking
parameters.

Where can I use regular expressions?
• Many text editors
– Notepad++ is an awesome one for Windows
• SEO Tools for Excel add-on
– http://nielsbosma.se/projects/seotools/
• Google Docs
– =regexextract() function
– =regexmatch() function
– =regexreplace() function
• Google Analytics
• Screaming Frog
• DeepCrawl
• .htaccess
– RewriteCond
– RewriteRule
• Programming Languages

RegEx Basics
Each one of these you learn, the more helpful it is.
You don’t have to learn all of them.

Anchors
• “Anchors” match position in text rather than text
itself:
– ^ (carat) will match the beginning of a line
– $ (dollar sign) will match the end of a line
Example: word word word word
• ^word  will result in “word word word word”
• word$  will result in “word word word word”

Character Classes
• [ starts a character class
• ] ends a character class
– Any of the characters within [ ] will be matched
Note: ranges like [G-V] (letters g though v) or [1-10] (number 1 through
10) also work.
Example: hnaeyesdtlaeck
• [nedl]  will result in “hnaeyesdtlaeck”
Example: Do you do SEO or SEM?
• SE[OM]  will result in “Do you do SEO or SEM?”

Miscellaneous Special Characters
• | (pipe) means OR
Example: this or that?
– this|that will result in “this or that?”
• . (period) represents any character (wildcard)
Example: Excuse my French; Detect profanity like
shit, sh#t, or sh!t.
– sh.t will result in “Detect profanity like shit, sh#t, or sh!t.”

Escaping Characters
There are many characters in regular expressions which
have special meanings, so if you wish to find the literal
characters they must be “escaped” with a backslash
preceding it.
Example: I want to find the period.
– .  I want to find the period.
– If I used just a period without escaping with a backslash:
.  will result in “I want to find the period.”

Quantifiers
• ? (question mark) means optional. It matches 0 or 1 of the
previous character, essentially making it optional.
Example: is the url http or https?
– https?  will result in “is the url http or https?”
• * (asterisk) means zero or more. It will find 0 or more occurrences
of the previous character.
Example #1: What’s that photo website again? Is it Flickr, Flicker, or Flickeeer?
– Flicke*r  will result in “What’s that photo website again? Is it Flickr, Flicker, or Flickeeer?”
Example #2: hlp help heelp heeeeeeeelp
– he*lp  will result in “hlp help heelp heeeeeeeelp”

Quantifiers - Continued
• + (plus) means one or more. It will find 1 or more
occurrences of the previous character.
Example #1: hlp help heelp heeeeeeeelp
– he+lp  will result in “hlp help heelp heeeeeeeelp”
Example #2: hlp help heelp heeeeeeeelp hellllllllp
• h.+lp  will result in “hlp help heelp heeeeeeeelp
hellllllllp”

Understanding Differences Between Quantifiers
Animated GIF Example

Quantifiers - Continued
• { } will match a certain quantity of previous
characters. You can also specify a range, like “1 to
3” or “3 or more” if you include a , (comma) inside
the brackets.
Example #1: buz buzz buzzz buzzzz buzzzzz
– buz{3}  will result in “buz buzz buzzz buzzzz buzzzzz”
Note: {3} reads “exactly 3} in plain english.
– buz{2,4}  will result in “buz buzz buzzz buzzzz buzzzzz”
Note: {2,4} reads “2 to 4” in plain english.

Groups
• Groups are encapsulated in parenthesis ( )
Example: hahaha haha ha haha ha!
– (ha)+  will render “hahaha haha ha haha ha!”
( )COPYRIGHT 2014 CATALYST. ALL RIGHTS RESERVED. APRIL 29, 2014 | PAGE 14

Capture Groups
• Groups can also be easily captured as variables that
can be repeated back:
– $1 would display the contents of the first group, $2 would
display the contents of the second group and so on.
Example: hello I am paul
– hello I am (.+)  used with $1  will capture “paul”
• To disable the capturing of groups we use (?:), so that they
can be used solely for the purpose of grouping patterns together.
So with the above example, (?:.+) will not capture anything

Lookarounds
• Positive Lookaheads will match a group after the main pattern
without actually including it in the result. The expression is
(?=)
Example: 1in 250px 2in 3em 40px
– [0-9]+(?=px)  will result in “1in 250px 2in 3em 40px”
Everything WITH “px”
• A Negative Lookahead is used to specify a group that won’t
be matched after the main pattern. The expression is (?!)
Example: 1in 250px 2in 3em 40px
– [0-9]+(?!em)  will result in “1in 250px 2in 3em 40px”
Everything BUT “em”

RegEx in Practice
Real Use Cases

Problem #1
I want to take a list of >2,000 Mashable.com URLs,
exported from BuzzSumo.com and segment the
<titles> into different segments (list posts, title as a
question, etc.) and see which ones received a
greater number of social shares.
What is the fastest way of doing this?
Hint:

Solution #1: SEO Tools for Excel Add-on w/ RegEx
• Is the post title a question?
– =RegexpIsMatch(A2,"?$")
• Is the post a listacle/list post?
– =RegexpIsMatch(A2,"^[0-9]*s|^[0-9],[0-9]*s")
• Extract publishing year from URL
– =RegexpFind(D2,"https?://(?:www.)?mashable.com/([0-
9]{4})/.+","$1")
• Presence of a year in the title
– =IFERROR(RegexpFind(A40,"([0-9]{4})","$1"),“N/A")

Nice! Took < 1 Minute.

Problem #2
• There are hundreds of pages with <span> tags
that should be rendered as <h2>. Some have
class and/or id attributes and some don’t. I want
to grab the contents (only) of these span tags for
a client.
What is the fastest way?
…RegEx!

Solution #2: SEO Tools for Excel Add-on w/ RegEx
• For a list of URL in Excel, and again with the SEO
Tool for Excel add-on, use a regular expression
like this:
– =RegexpFindOnUrl(D3,"<span(?:.+)?>(.+)</span>",1)

Problem #3:
• I want to grab the full description from a long list of
YouTube videos. We can grab it from the meta
description, but it might be an incomplete
description that is truncated, so we need to grab
the actual page text.
What’s the fastest way?

…Probably XPath, but we can also use RegEx 

Solution #3: SEO Tools for Excel Add-on
• For a list of YouTube video URLs in Excel, use the
SEO Tools for Excel Add-on with the following
regular expression:
– =RegexpFindOnUrl(A1,"<p id=.eow-
description.s?>(.+)</p>",1)
Please note, that because the HTML utilized a double-
quote, you have to use another character in its place so as
not to break Excel, like the period, to represent ANY
character.

Problem #4
• I want to quickly change a long list of keywords
into the exact match format with the keyword
surrounded by brackets, [ ].

Solution #4: Notepad++ Example
1. Copy a column of keywords
from Excel into Notepad++
2. Control + F and switch to the
“Replace” tab.
3. Switch the “Search Mode” to
“Regular Expression”
4. Enter ^ in the “Find what” field
and [ in the “Replace with” field.
5. Hit the “Replace All” button.
6. Then, enter $ in the “Find what”
field and ] in the “Replace with”
field.
7. Again, hit the “Replace All”
button.

Problem #5
• I want to identify which keywords from Google
Webmaster Tools is Branded/Non-
Branded, along with misspellings, from our SQL
database in Spotfire.

Other Places We Might Use RegEx
Google Analytics supports regular expressions:
– When creating filters
– When setting up goals
– When defining goal funnel steps
– When defining advanced segments
– When using report filters
– When using filters in multichannel reporting
h/t Annie Cushing

.htaccess
– Redirect a set of URLs matching a certain pattern to a new URL
pattern:
Example:
RewriteRule ^/dir/index.php?id=(0-9+).htm$ file-$1 [L]
Screaming Frog
– URL Rewriting: RegEx Replace
– Spider Include/Exclude URLs

Deepcrawl

Resources
Helpful tool for testing RegEx and gives a good
breakdown of your patterns:
• http://www.regexr.com/
A handy cheat sheet to print and put on your desk:
• http://www.cheatography.com/davechild/cheat-
sheets/regular-expressions/pdf/
SEO Tools for Excel Add-on
• http://nielsbosma.se/projects/seotools/
Notepad++
• http://notepad-plus-plus.org/

Thank You!
Paul Shapiro
paul.shapiro@catalystsearchmarketing.com
@fighto
http://blog.paulshapiro.com

Regular Expressions for Regular Joes (and SEOs)

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