Regular Expressions

Match a lower case word that starts with and ends with the same letters

([a-z])[a-z]*\1

Match the word cat or bobcat with any capitilzation

([bB][oO][bB])?[cC][aA][tT]

Match the word data repeated any number of times and ending with a single digit

(data)+\d

Write a regular expression that matches cat? Hat. bAt# 123! but does not match fatt Dan9 zApS

...\W or \w\w\w\W

What is a -1 in the Pearson Product-Moment Correlation?

A perfect negative correlation

What is a 1 in the Pearson Product- Moment Correlation?

A perfect positive correlation

What is an Engine?

A piece of software that can process these expressions and attempt to match the pattern to a given string.

What would the string \D\s\d look for?

A sequence that is any non-digit number followed by a space followed by a digit from 0-9

What is the Pearson Product-Moment Correltation

A value between -1 and 1

What do we need in order to use regular expressions?

An "engine"

What is a Literal?

Any character we use in a search or matching expression (E.g. to find ind in windows the ind is the literal string).

Character Classes: What would the pattern [0-9] match? What about [B-E]?

Any digit; Any upper case letters between B and E (upper case in specific)

What would \d\d find?

Any string of 2 digits from 0-9 in the data set

What would the patter \D\D\D find?

Any string of 3 non digit characters in a data set

How does the CORREL function work out?

CORREL (array 1, array 2)

What does the CORREL or Pearson Product-Moment Correlation attempt to do?

Draw a line of best fit through the data?

What is everything in data (in regards to regular expressions)

Everything is essentially a character.

What does a ^ at the start of a character class do?

Excludes any characters in the class (matches characters not listed between the square brackets)

What is an escape sequence

Is a way of indicating that we want to use one of our meta characters as a literal.

What is a meta-character?

Is one or more special characters that have a unique meaning and are not used as literals in the search expression. (e.g. \/ ^ $ [ ] + * Etc.)

What specific kinds of correlations does the Pearson-Product Moment correlation work?

Linear Correlations

What does \r do?

Looks for a cartridge return

What does \n do?

Looks for a line break

what does \s do?

Looks for a space

What does \t do?

Looks for a tab

What does \S do?

Looks for anything that is not a space

What would the sequence \d\.\d match?

Match a one digit number with a single decimal place

What would the line \w\r\n\w do?

Match a word character followed by the end of a line and another word character

What would the pattern [^bc]at find?

Match all three letter words that end in at except bat or cat

What would the search c.t find?

Match any three letter word starting with a 'c' and ending with a 't', can have numbers or characters in the middle

What would (...){min,max} match?

Match the pattern min to max times

What would (...)+ match?

Match the pattern one or more times

What would the patter (...)* match?

Match the pattern zero or more times

What would (...)? match

Match the pattern zero or one times

What would the patter [bc]at match?

Match the strings that have either a b or c and then an 'at' at the end. so if the example was bobcat --> match would be cat not bcat because it only gets a single character

What would [aeiou]{3,5} match?

Match three to five lower case vowels in a row

What would \d+ match?

Matches a digit one or more times

What would c.?t match?

Matches a word starting with c and ending with t that has any or no character between (ct, cat, czt, c6t, c%t)

Character Classes: What would [a-zA-Z] match? What about [a-zA-Z0-9]? What about [a-z\n\t]?

Matches any letter (upper or lower case). Matches any letter or digit. Matches any lower case letter and the tab or line break characters.

What does a . do? How would you match a period?

Matches any single character (letter, digit, white space, everything) To match a period you would need to search \.

What does ^ match?

Matches the beginning of a line (except when sued in a character class like [^...]

Kleene Star and Plus Notation: What does c* match?

Matches the caracter c zero or more times

Kleene Star and Plus Notation: What does c+ match?

Matches the character c one or more times

Kleene Star and Plus Notation: What does C? Match?

Matches the character c zero or one times

What does $ match?

Matches the end of a line

What would [a-z]* match?

Matches the lower case letters zero or more times.

Conditional: What would patt1 | patt 2

Matches the patter patt1 or patt2

Conditional: What would (patt1|patt2) match?

Matches the same part and can be part of a grouping

What do the \b's do in : \b([a-z])[a-z]*\1\b

Matches word boundaries

Do Correlations Imply Causation?

NO

What is a 0 in the Pearson Product-Moment Correlation

No correlation

What does the expression [xyz] match?

Only a single x y or z (the exact characters between the brackets).

How are letters and numbers expressed in regular expressions?

Ordinary characters (or literals) are matched literally (a matches a, b matches b, 1 matches 1)

Groups: What is the purpose of groups?

Sometimes we need to reference a match we made previously

How do we match whole lines and not allow partial matches?

Use anchors ^

What do Groups allow us to remember?

What we matched

What does a line ended with \r\n do?

When looking it moves to the next line.

Match a digit or a lower case letter

[a-z] | [0-9]

How do we match [ ] brackets?

\[ \]

What is the difference between \b and \B

\b is a word boundary \B is not a word boundary

difference between \d and \D

\d = is a digit \D = is not a digit

Write a regular expression to match the phone number patter ###-###-#### where # = any digit from 0-9

\d\d\d-\d\d\d-\d\d\d\d

What is the difference between \h and \H

\h is a horizontal space (space, tab, \n) \H is not a horizontal space

Difference between \l and \L

\l = is a lower case letter \L is not a lower case letter

What is the difference between \s and \S

\s is a spacing character \S is not a spacing character

What is the difference between \u and \U

\u is a upper case letter \U is not an upper case letter

What is the difference between \v and \V

\v is a vertical space \V is not a vertical space

What is the difference between \w and \W

\w is a word character \W is not a word character

Match a line of characters that begins with a single digit and a lower case letter and ends with the same lower case letter followed by the same digit.

^([0-9])([a-z]).*\2\1$

What are the two ways to match whole words?

^([a-z])[a-z]*\1$ - Only matches if word is only text on the line \b([a-z])[a-z]*\1\b - matches any whole word

Match a line that starts with hello

^Hello.* (looks for a line beginning with hello and then searches for any character one or more times)

How would you match lines that only have lower case letters?

^[a-z]+$

What is \R

any new line character (\n \r and others)

what is \r

cartridge return (CR control character)

Match the word cat or the word dog

cat | dog

What would xy?z match?

it would match xyz or xz (cause it matches y zero or one times)

What does \d do?

looks for any digit from 0 - 9

what does \D do?

looks for any non-digit character

what does \W do?

looks for any non-word character (non alphanumeric)

what does \w do?

looks for any word character (alphanumeric)

What does the pattern [x-y] do?

matches any character between x and y alphabetically

What does c{n} match? What would c{3,5} match?

matches the character c, n times matches c 3 to 5 times times.

what is \n

new line

what is ^

start of a line

What is \t

tab character

what is $

the end of a line

Repetitions: What is the notation for matching a character multiple times?

{min, max}