Getting the last word in each line

Ruby
1

Is there a prettier way to read a file and return the last word in each
line?

Here’s my go:

File.read(some_file).to_a.map { |l| line.split.last }

What if I wanted to search the lines (based on a regex) and return the
last word in each line that satisfied the search criteria?

Joe

2

Hello !

File.read(some_file).to_a.map { |l| line.split.last }

What if I wanted to search the lines (based on a regex) and return the
last word in each line that satisfied the search criteria?

What about

File.read(some_file).to_a.map { |l| line.split.select {|v| v =~
/regex/}.last }

Vince
3

On Wed, Sep 13, 2006, Joe Van D. wrote:

Is there a prettier way to read a file and return the last word in each
line?

Well, there’s #readlines…

File.readlines(‘somefile’).map {|f| f.split.last}

…which is a little nicer.

What if I wanted to search the lines (based on a regex) and return the
last word in each line that satisfied the search criteria?

File.readlines(‘somefile’).map do |f|
next unless f =~ /regex/
f.split.last
end

But you’ll have nils everywhere that a line was next’ed over…

File.readlines(‘somefile’).reject{|f| f !~ /regex/}.map {|f|
f.split.last}

Someone else might have an elegant solution, but these will work :slight_smile:

Ben

4

in irb:

r = /\w+$/
=> /\w+$/

s = “bad boy”
=> “bad boy”

md = s.match®
=> #MatchData:0x2cae00c

md[0]
=> “boy”

Joe Van D. wrote:

Is there a prettier way to read a file and return the last word in each
line?

Here’s my go:

File.read(some_file).to_a.map { |l| line.split.last }

What if I wanted to search the lines (based on a regex) and return the
last word in each line that satisfied the search criteria?

Joe

5

Hi,

At Wed, 13 Sep 2006 06:57:47 +0900,
Joe Van D. wrote in [ruby-talk:214152]:

File.read(some_file).to_a.map { |l| line.split.last }

$ ruby -e ‘p open(ARGV[0]){|f|f.grep(/(\w+)\s*$/){$1}}’ version.h
[“190”, “20060912”, “1”, “9”, “0”, “2006”, “9”, “12”]

6

Joe Van D. wrote:

File.read(some_file).to_a.map { |l| line.split.last }

line[/(\w+)\s*$/, 1]

might be faster than line.split.last. Worth trying anway.

7

On Wed, Sep 13, 2006 at 07:18:44AM +0900, Vincent F. wrote:

What about

File.read(some_file).to_a.map { |l| line.split.select {|v| v =~
/regex/}.last }
That call to_a is unecessary. File.read(some_file).map { … } will work
just as well.