Question

I’m new to ruby and I’m trying to solve a problem.

I’m parsing through several text field where I want to remove the header which has different values. It works fine when the header always is the same:

variable = variable.gsub(/(^Header_1:$)/, '')

But when I put in several arguments it doesn’t work:

variable = variable.gsub(/(^Header_1$)/ || /(^Header_2$)/ || /(^Header_3$)/ || /(^Header_4$)/ || /^:$/, '')

Answer 1

You can use Regexp.union:

regex = Regexp.union(
  /^Header_1/,
  /^Header_2/,
  /^Header_3/,
  /^Header_4/,
  /^:$/
)
variable.gsub(regex, '')

Please note that ^something$ will not work on strings containing something more than something 🙂

Cause ^ is for matching beginning of string and $ is for end of string.

So i intentionally removed $.

Also you do not need brackets when you only need to remove the matched string.

You can also use it like this:

headers = %w[Header_1 Header_2 Header_3]
regex = Regexp.union(*headers.map{|s| /^#{s}/}, /^\:$/, /etc/)
variable.gsub(regex, '')

And of course you can remove headers without explicitly define them.

Most likely there are a white space after headers?

If so, you can do it as simple as:

variable = "Header_1 something else"
puts variable.gsub(/(^Header[^\s]*)?(.*)/, '\2')
#=>  something else

variable = "Header_BLAH something else"
puts variable.gsub(/(^Header[^\s]*)?(.*)/, '\2')
#=>  something else