Array of Strings to Convert to Mixed Array

I'm trying to convert an Array of Arrays consisting of Ruby Strings into an Array of Arrays consisting of Strings and Floats.

Here is my attempt:

array = [["My", "2"], ["Cute"], ["Dog", "4"]]
array.collect! do |x|
x.each do |y|
if y.gsub!(/\d+/){|s|s.to_f}
end
end
end

=> [["My", "2.0"], ["Cute"], ["Dog", "4.0"]]

I'm looking for this to rather return 

[["My",
2.0], ["Cute"], ["Dog", 4.0]]

 What did I do wrong?

What you did wrong is that you used 

gsub!

.
That takes a string and changes the string. It doesn't turn it into anything else, no matter what you do (even if you convert it to a float in the middle).

A simple way to achieve what you want is:

[["My", "2"], ["Cute"], ["Dog", "4"]].map{|s1, s2| [s1, *(s2.to_f if s2)]}

If you do not want to create the element array, but replace its contents, then:

[["My", "2"], ["Cute"], ["Dog", "4"]].each{|a| a[1] = a[1].to_f if a[1]}

If the numerical strings appear in random positions, then:

[["My", "2"], ["Cute"], ["Dog", "4"]]
.each{|a| a.each.with_index{|e, i| a[i] = a[i].to_f if a[i] and a[i] =~ /\d+/}}