How to change stdin separator (perl vs ruby)

Ruby
1

I have to process very very big text files and not line per line, I have
to access to a group of lines seperated for a “%”. Then I tryed to
access line per line and detect the separator for each line saving the
lines in a buffer, obviously it works but it’s very slow (text files are
bigger than 1GB).

Perl have an awesome feature that is to change the separator for
iterating files (by default in all languages is “\n”), this simple and
extremely efficent code do what I need:

$/ = “%”;
while ($article = ) {
#Iteration
}

I can write a equivalent code in ruby but not (by far) as efficient as
perl. Someone knows how can I change the separator for iterate the stdin
in ruby?

Thanks!

2

2010/2/10 Sak … [email protected]:

$/ = “%”;
while ($article = ) {
#Iteration
}

I can write a equivalent code in ruby but not (by far) as efficient as
perl. Someone knows how can I change the separator for iterate the stdin
in ruby?

STDIN.each_line("%") { |line|
  # iteration
}

Stefan

3

On Wed, Feb 10, 2010 at 4:23 PM, Sak … [email protected] wrote:

I can write a equivalent code in ruby but not (by far) as efficient as
perl. Someone knows how can I change the separator for iterate the stdin
in ruby?

Ruby has also $/ among its global variables. The methods #gets and
#readline take it into account. Those methods and #each also accept a
separator as an optional argument.

In Ruby 1.9 they additionally accept an integer, that’s the same as
setting $/ to a reference to an integer in Perl.

4

On Thu, Feb 11, 2010 at 12:23:55AM +0900, Sak … wrote:

$/ = “%”;
while ($article = ) {
#Iteration
}

If your delimiter only occurs as a delimiter, and not in the data as
well:

File.open(path_to_file, ‘r’) do |f|
f.each(’%’) do |record|
# Do stuff.
end
end

5

Stefan L. wrote:

2010/2/10 Sak … [email protected]:

$/ = “%”;
while ($article = ) {
�#Iteration
}

I can write a equivalent code in ruby but not (by far) as efficient as
perl. Someone knows how can I change the separator for iterate the stdin
in ruby?

STDIN.each_line("%") { |line|
  # iteration
}

Stefan

Thanks Stefan for the answer, that’s exactly what I need, thanks Xavier
explanation is perfect. Thanks Daniel, good observation.

6

2010/2/10 Daniel B. [email protected]:

$/ = “%”;
while ($article = ) {
#Iteration
}

If your delimiter only occurs as a delimiter, and not in the data as well:

Note that this statement is true for \n as well!

File.open(path_to_file, ‘r’) do |f|
f.each(‘%’) do |record|

Do stuff.

end
end

You can have it simpler:

File.foreach path, ‘%’ do |record|

so something with record

end

Kind regards

robert