从Ruby中的数组数组中的一列中选择所有元素?

I have an array of arrays:

我有一个数组:

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

And I want an array containing only the third column of each of the arrays:

我想要一个数组只包含每个数组的第三列:

res = ["1", "2", "3", "4"]

How would I do that?

我该怎么做呢?

I want to type something like:

我想输入如下内容:

arr[][2]

But thinking more Ruby-like, I tried:

但我想的更像红宝石，我试着:

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

but this returns the whole row.

但它返回整行。

3 个解决方案

#1

You want arr.map {|row| row[2]}

加勒比海盗。地图{ | |行[2]}

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

arr.map {|row| row[2]}
# => ["1", "2", "3", "4"]

#2

Another method:

另一种方法:

arr.transpose[2]

#3

Use map or collect arr.map { |a| a[2]}

使用地图或收集arr。地图{ | |一个[2]}

#1