get values from ruby array if condition

Question

I'm mapping a array with this code:

url = "http://www.cnn.com"
page = Mechanize.new.get(url)
images_url = page.images.map{|img| img.url.to_s if (img.width.to_i > 200)}

I get this result in console:

[nil, "http://i2.cdn.turner.com/cnn/dam/assets/110929092349-nelson-mandela-t1-main.jpg", nil, nil, nil, nil, nil, "http://i2.cdn.turner.com/cnn/dam/assets/120225123812-syria-mani-2-c1-main.jpg", nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, "http://i2.cdn.turner.com/cnn/dam/assets/120225022127-blue-fish-bin-tease.jpg", nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil]

I want get this array without nil values, its mean, I want get a array sth like:

["http://i2.cdn.turner.com/cnn/dam/assets/110929092349-nelson-mandela-t1-main.jpg", "http://i2.cdn.turner.com/cnn/dam/assets/120225123812-syria-mani-2-c1-main.jpg", "http://i2.cdn.turner.com/cnn/dam/assets/120225022127-blue-fish-bin-tease.jpg"]

For this case, 3 values.

Thank you

Matteo Alessani · Accepted Answer · 2012-02-25 16:32:24Z

9

You can call the compact method on your Array to remove empty results from it.

images_url = page.images.map{|img| img.url.to_s if (img.width.to_i > 200)}.compact

answered Feb 25, 2012 at 16:32

Matteo Alessani

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5 Comments

hyperrjas Over a year ago

Thank you Matteo could you put the example for this case?. Thank you!

Matteo Alessani Over a year ago

sure, I've just added it to the answer

hyperrjas Over a year ago

images_url = page.images.map{|img| img.url.to_s if (img.width.to_i > 200)}.compact!

brymck Over a year ago

@hyperrjas You don't want compact!. If there are no nil values in the array, compact! will return nil instead of the list of URLs. You probably want compact (i.e. without the !, as in Matteo's example).

Rahul Over a year ago

nice. i have been using <code>reject{|i| i.nil?}</code> till now

Jwosty · Accepted Answer · 2012-02-25 18:35:45Z

You can also use Array#delete if you ever want to remove things other than nil, without modifying the receiver (add an bang [!] if you want do want it to.

Or if you want to delete elements based on something other than if it matches, you can use Array#delete_if. It iterates over each element with a block you provide and removes the element if the return value of that block evaluates to true.

Here are some examples of both:

    ary = [42, nil, "foo", "bar", "foo", Object.new, self, /hi/]
    ary.delete("foo")  #=> [42, nil, 'bar', #<Object:xxxxx&rt, main, /hi/]
    ary                #=> [42, nil, "foo", "bar", "foo", Object.new, self, /hi/]
    ary.delete_if {|elem|
      elem.class == Object or
      elem.kind_of?(Regexp)
    }                  #=> [42, nil, "foo", "bar", "foo"]

Hope this helps! :)

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