CODEWITHSUNDEEP
ruby-on-railsregexstringruby-on-rails-5
Dave
Dave

Reputation: 19110

How do I trim a Rails string based on a condition?

I'm using Rails 5. How do I remove all words from the beginning of my string whose first character is not a letter (i.e. !~ /\p{L}/)? So if I have a string

"1000  22  cc33 dfdsf"

I would want the result to be

"cc33 dfdsf"

Similarly, if the string were

"7nnn 2000   388   a  4000 bbb"

I would expect the result to be

"a  4000 bbb"

Upvotes: 1

Views: 276

Answers (2)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626747

I suppose the "words" are just chunks of non-whitespace symbols.

You may use

rx = /\G[^[:space:]\p{L}][^[:space:]]*[[:space:]]*/

puts "1000  22  cc33 dfdsf".gsub(rx, '')             # => cc33 dfdsf
puts "7nnn 2000   388   a  4000 bbb".gsub(rx, '')    # => a  4000 bbb

See the Ruby demo online

Details:

  • \G - start of string or the end of the previous match (thus, we only get consecutive matches from the start of the string)
  • [^[:space:]\p{L}] - a char that is not a whitespace and not a letter
  • [^[:space:]]* - 0+ non-whitespaces
  • [[:space:]]* - 0+ whitespaces.

Another regex you can use is /\A(?:[^[:space:]\p{L}][^[:space:]]*[[:space:]]*)+/. Here, \A matches the start of the string, and (?:...)+ matches 1 or more consecutive occurrences of the pattern described above.

NOTE: If you want to match specifically alphanumeric words, that is, if you want to remove all words starting with a digit at the beginning of the string, you may use

/\G\p{N}[[:alnum:]]*[^[:alnum:]]*/

or

/\A(?:\p{N}[[:alnum:]]*[^[:alnum:]]*)+/

where \p{N} matches any digit, [[:alnum:]] matches any alphanumeric and [^[:alnum:]] matches any char that is not alphanumeric. See another Ruby demo.

Upvotes: 2

zhulien
zhulien

Reputation: 5695

This pattern searches until it finds the first occurence of a "word" by your criteria and then it takes everything till the end of the string. You can extract the result in from the matched group.

.*?\b([A-Za-z].*)

Swap it for:

.*?\b([A-Za-z][\s\S]*)

if you need line terminators included.

Upvotes: 0

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