G lgame matches lame and game but not the last four

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Unformatted text preview: by
hand,
so
that
 we
can
easily
reproduce
our
work
if
needed.
 
 • 

A
regular
expression
(aka
regex
or
regexp)
is
 a
paNern
that
describes
a
set
of
strings.


 • 

This
set
may
be
finite
or
infinite,
depending
 on
the
par0cular
regexp.
We
say
the
regexp
 “matches 
each
element
of
that
set.

 • 

For
example,
the
regexp

 grey|gray matches
both
grey
and
gray,
whereas

 ^A.*

 matches
any
string
star0ng
with
capital
A.
 • 

The
idea
is
similar
to
wildcards
in
UNIX,
but
 with
many
more
possibili0es.
 With
regular
expressions,
we
can
 •  extract
pieces
of
text
–
e.g.,
find
all
links
in
an
 HTML
document
 •  create
variables
from
informa0on
found
in
 text
 •  clean
and
transform
text
into
a
uniform
 format,
resolving
inconsistencies
in
format
 between
...
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This note was uploaded on 05/08/2013 for the course STAT 133 taught by Professor Staff during the Fall '08 term at University of California, Berkeley.

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