I'm trying to match regex groups over a series of lines and getting stumped. Data file has lines that look like this:
2014-03-01 08:19,47.799107662994,-75.876391553881,some comment,James,#tag
Here is my Ruby code:
regex = /(?<day>.*)\s(?<hour>\d*:\d*),(?<lat>.*),(?<long>.*),(?<entry>.*),(?<people>.*),#(?<tag>.*)/
f = File.open("/Users/USERNAME/path/to/file.txt", encoding: 'UTF-8')
lines = f.read
f.close
lines.each_line do |line|
if line =~ /&/
line.gsub!(/[&]/, 'and')
end
if regex =~ line
puts line
end
end
That works, but if I change that third to last to line to, for example puts day, then I get an error saying that is an undefined local variable. My understanding was that =~ automatically defined those variables.
Any idea what I'm doing wrong?
From the Ruby Rexexp docs:
When named capture groups are used with a literal regexp on the left-hand side of an expression and the =~ operator, the captured text is also assigned to local variables with corresponding names.
So it needs to be a literal regex that is used in order to create the local variables.
In your case you are using a variable to reference the regex, not a literal.
For example:
regex = /(?<day>.*)/
regex =~ 'whatever'
puts day
produces NameError: undefined local variable or method `day' for main:Object, but this
/(?<day>.*)/ =~ 'whatever'
puts day
prints whatever.
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