This is a common, repetitive idiom for me: filtering an array using a regular expression, and returning a sub-array. My approach doesn't seem very Ruby-like (I come from Java). I end up having many methods which look a lot like this.
What is the idiomatic Ruby way to improve this code?
def get_all_gifs(items_)
output = Array.new
filter = /\.jpg$/
items_.each do |item|
next if item =~ filter
output << item
end
output
end
If you want to find all gifs:
def get_all_gifs(files)
files.select{ |i| i[/\.gif$/] }
end
If you want to find all jpegs:
def get_all_jpgs(files)
files.select{ |i| i[/\.jpe?g$/] }
end
Running them:
files = %w[foo.gif bar.jpg foo.jpeg bar.gif]
get_all_gifs(files) # => ["foo.gif", "bar.gif"]
get_all_jpgs(files) # => ["bar.jpg", "foo.jpeg"]
But wait! There's more!
What if you want to group them all by their type, then extract based on the extension?:
def get_all_images_by_type(files)
files.group_by{ |f| File.extname(f) }
end
Here's the types of files:
get_all_images_by_type(files).keys # => [".gif", ".jpg", ".jpeg"]
Here's how to grab specific types:
get_all_images_by_type(files) # => {".gif"=>["foo.gif", "bar.gif"], ".jpg"=>["bar.jpg"], ".jpeg"=>["foo.jpeg"]}
get_all_images_by_type(files)['.gif'] # => ["foo.gif", "bar.gif"]
get_all_images_by_type(files).values_at('.jpg', '.jpeg') # => [["bar.jpg"], ["foo.jpeg"]]
Have a look at Enumerable.grep, it's a very powerful way of finding/filtering things in anything enumerable.
grep is great, in part because it uses === to compare elements of the receiver to grep's argument. That allows you to write, for example, ["abc", "bcd", "cbd"].grep(/.b./) #=> ["abc", "cbd"] and [{a:1}, 4, {b:2}, "hat"].grep(Hash) #=> [{:a=>1}, {:b=>2}].$ cat foo.rb
images = %w[foo.gif foo.png foo.jpg bar.jpeg moo.JPG]
jpgs = images.select{|e| e =~ /\.jpe?g$/i}
puts jpgs.inspect
$ ruby foo.rb
["foo.jpg", "bar.jpeg", "moo.JPG"]
The change to your regexp is so that you can match "jpeg" in addition to "jpg" regardless of case.
images = %w[foo.gif foo.png foo.jpg bar.jpeg moo.JPG]
images.grep(/.jpg/i) # => ["foo.jpg", "moo.JPG"]
.match also??We can go without regex for this specific problem. Use String#end_with?
images = %w[foo.gif foo.png foo.jpg bar.jpeg moo.JPG]
images.find_all{|e| e.end_with?(".jpg",".jpeg")}
# => ["foo.jpg", "bar.jpeg"]
ta, tb = files.partition{|f| f[/(.*\.jpe*g)/]}
ap ta
[
[0] "bar.jpg",
[1] "foo.jpeg"
]
ap tb
[
[0] "foo.gif",
[1] "bar.gif"
]
/gucio
Dir.glob('*.jpe?g')