从Ruby中的数组中的一列中选择所有元素？

我有一个数组：

arr = [["Foo1","Bar1","1","W"],["Foo2","Bar2","2","X"],["Foo3","Bar3","3","Y"],["Foo4","Bar4","4","Z"]]

而且我想要一个仅包含每个数组的第三列的数组：

res = ["1","4"]

我该怎么办？

我想输入：

arr[][2]

但是想像Ruby一样,我试过：

arr.select{ |r| r[2] }

但这返回整行.

解决方法

你想要arr.map {| row |行[2]}

arr = [["Foo1","Z"]]

arr.map {|row| row[2]}
# => ["1","4"]