Split on different newlines
RubyRegexSplitNewlineRuby Problem Overview
Right now I'm doing a split on a string and assuming that the newline from the user is \r\n like so:
string.split(/\r\n/)
What I'd like to do is split on either \r\n or just \n.
So how what would the regex be to split on either of those?
Ruby Solutions
Solution 1 - Ruby
Did you try /\r?\n/ ? The ? makes the \r optional.
Example usage: http://rubular.com/r/1ZuihD0YfF
Solution 2 - Ruby
Ruby has the methods String#each_line and String#lines
returns an enum: http://www.ruby-doc.org/core-1.9.3/String.html#method-i-each_line
returns an array: http://www.ruby-doc.org/core-2.1.2/String.html#method-i-lines
I didn't test it against your scenario but I bet it will work better than manually choosing the newline chars.
Solution 3 - Ruby
# Split on \r\n or just \n
string.split( /\r?\n/ )
Although it doesn't help with this question (where you do need a regex), note that String#split does not require a regex argument. Your original code could also have been string.split( "\r\n" ).
Solution 4 - Ruby
\n is for unix
\r is for mac
\r\n is for windows format
To be safe for operating systems. I would do /\r?\n|\r\n?/
"1\r2\n3\r\n4\n\n5\r\r6\r\n\r\n7".split(/\r?\n|\r\n?/)
=> ["1", "2", "3", "4", "", "5", "", "6", "", "7"]
Solution 5 - Ruby
The alternation operator in Ruby Regexp is the same as in standard regular expressions: |
So, the obvious solution would be
/\r\n|\n/
which is the same as
/\r?\n/
i.e. an optional \r followed by a mandatory \n.
Solution 6 - Ruby
Are you reading from a file, or from standard in?
If you're reading from a file, and the file is in text mode, rather than binary mode, or you're reading from standard in, you won't have to deal with \r\n - it'll just look like \n.
C:\Documents and Settings\username>irb
irb(main):001:0> gets
foo
=> "foo\n"
Solution 7 - Ruby
Perhaps do a split on only '\n' and remove the '\r' if it exists?
Solution 8 - Ruby
Another option is to use String#chomp, which also handles newlines intelligently by itself.
You can accomplish what you are after with something like:
lines = string.lines.map(&:chomp)
Or if you are dealing with something large enough that memory use is a concern:
<string|io>.each_line do |line|
line.chomp!
# do work..
end
Performance isn't always the most important thing when solving this kind of problem, but it is worth noting the chomp solution is also a bit faster than using a regex.
On my machine (i7, ruby 2.1.9):
Warming up --------------------------------------
map/chomp 14.715k i/100ms
split custom regex 12.383k i/100ms
Calculating -------------------------------------
map/chomp 158.590k (± 4.4%) i/s - 794.610k in 5.020908s
split custom regex 128.722k (± 5.1%) i/s - 643.916k in 5.016150s