Replacing "\ n" but not "\ n \ n"
You can use a regular expression /(?<!\n)\n(?!\n)/
that matches \n
only if it is not prefixed with something other \n
than with \n
.
text1 = "Hello\nWorld"
# => "Hello\nWorld"
text1.sub /(?<!\n)\n(?!\n)/, " \n"
# => "Hello \nWorld"
text2 = "Hello\n\nWorld"
# => "Hello\n\nWorld"
text2.sub /(?<!\n)\n(?!\n)/, " \n"
# => "Hello\n\nWorld"
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Here's another way:
r = /\n+/
"Hello\nWorld".sub(r) { |s| (s.size==1) ? " \n" : s }
#=> "Hello \nWorld"
"Hello\n\nWorld".sub(r) { |s| (s.size==1) ? " \n" : s }
#=> "Hello\n\nWorld"
and one more:
h = Hash.new { |h,k| h[k] = k }.update("\n"=>" \n")
#=> {"\n"=>" \n"}
"Hello\nWorld".sub(r,h)
#=> "Hello \nWorld"
"Hello\n\nWorld".sub(r,h)
#=> "Hello\n\nWorld"
In the last method, each line of one or more consecutive newlines is passed into a hash. If it is one new line, it "\n"
is replaced with h["\n"] #=> " \n"
. If it has two or more newlines, for example s = "\n\n"
and h
does not have a key equal to s
(at first it won't), the key value pair s=>s
will be appended to h
(due to the default value defined for the hash) and s
will be replaced by itself ...
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Another solution you could use:
string = "Hello\nWorld"
string.split("\n") == string.split("\n").reject(&:empty?) ? string.sub!("\n", " \n") : string
#=> "Hello \nWorld"
string = "Hello\n\nWorld"
string.split("\n") == string.split("\n").reject(&:empty?) ? string.sub!("\n", " \n") : string
#=> "Hello\n\nWorld"
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