如何将字符串数组的数组转换为Ruby中的浮点数？

Question

下面的代码字符串数组转换成float数组：

a = ["4", "5.5", "6"] 
a.collect do |value| 
    value.to_f 
end 
=> [4.0, 5.5, 6.0] 

为什么下面的返回一个字符串，而不是float数组？

b = [ ["0.0034", "-0.0244", "0.0213", "-0.099"], 
     ["0.0947", "-0.1231", "-0.1363", "0.0501"], 
     ["-0.0368", "-0.1769", "-0.0327", "-0.113"], 
     ["0.0936", "-0.0987", "-0.0971", "0.1156"], 
     ["0.0029", "-0.1109", "-0.1226", "-0.0133"] ] 

b.each do |row| 
    row.collect do |value| 
     value.to_f 
    end 
end 
=> [["0.0034", "-0.0244", "0.0213", "-0.099"], ["0.0947", "-0.1231", "-0.1363", "0.0501"], ["-0.0368", "-0.1769", "-0.0327", "-0.113"], ["0.0936", "-0.0987", "-0.0971", "0.1156"], ["0.0029", "-0.1109", "-0.1226", "-0.0133"]] 

另外，有没有更好的方法来做到这一点？

Answer 1

由于您在b而不是collect上致电each，您最终将返回原始数组而不是新创建的数组。下面是正确的代码（我喜欢地图收集，但是这只是我）：

b.map{ |arr| arr.map{ |v| v.to_f } }