Extract a substring from a string in Ruby using a regular expression
RubyRegexStringSubstringRuby Problem Overview
How can I extract a substring from within a string in Ruby?
Example:
String1 = "<name> <substring>"
I want to extract substring
from String1
(i.e. everything within the last occurrence of <
and >
).
Ruby Solutions
Solution 1 - Ruby
"<name> <substring>"[/.*<([^>]*)/,1]
=> "substring"
No need to use scan
, if we need only one result.
No need to use Python's match
, when we have Ruby's String[regexp,#]
.
See: http://ruby-doc.org/core/String.html#method-i-5B-5D
Note: str[regexp, capture] → new_str or nil
Solution 2 - Ruby
String1.scan(/<([^>]*)>/).last.first
scan
creates an array which, for each <item>
in String1
contains the text between the <
and the >
in a one-element array (because when used with a regex containing capturing groups, scan creates an array containing the captures for each match). last
gives you the last of those arrays and first
then gives you the string in it.
Solution 3 - Ruby
You can use a regular expression for that pretty easily…
Allowing spaces around the word (but not keeping them):
str.match(/< ?([^>]+) ?>\Z/)[1]
Or without the spaces allowed:
str.match(/<([^>]+)>\Z/)[1]
Solution 4 - Ruby
Here's a slightly more flexible approach using the match
method. With this, you can extract more than one string:
s = "<ants> <pants>"
matchdata = s.match(/<([^>]*)> <([^>]*)>/)
# Use 'captures' to get an array of the captures
matchdata.captures # ["ants","pants"]
# Or use raw indices
matchdata[0] # whole regex match: "<ants> <pants>"
matchdata[1] # first capture: "ants"
matchdata[2] # second capture: "pants"
Solution 5 - Ruby
A simpler scan would be:
String1.scan(/<(\S+)>/).last