我试着:
somearray = ["some", "thing"]
anotherarray = ["another", "thing"]
somearray.push(anotherarray.flatten!)
我预期的
["some", "thing", "another", "thing"]
但有
["some", "thing", nil]
当前回答
我发现更容易推入或追加数组，然后将它们压平，如下所示:
somearray = ["some", "thing"]
anotherarray = ["another", "thing"]
somearray.push anotherarray # => ["some", "thing", ["another", "thing"]]
#or
somearray << anotherarray # => ["some", "thing", ["another", "thing"]]
somearray.flatten! # => ["some", "thing", "another", "thing"]
somearray # => ["some", "thing", "another", "thing"]
其他回答
你有一个可行的想法，但#flatten!在错误的地方——它会使接收器变平，所以你可以用它把[1,2，['foo'， 'bar']]变成[1,2，'foo'，'bar']。
毫无疑问，我忘记了一些方法，但你可以串联起来:
a1.concat a2
a1 + a2 # creates a new array, as does a1 += a2
或预先考虑/追加:
a1.push(*a2) # note the asterisk
a2.unshift(*a1) # note the asterisk, and that a2 is the receiver
或接头:
a1[a1.length, 0] = a2
a1[a1.length..0] = a2
a1.insert(a1.length, *a2)
或append和flatten:
(a1 << a2).flatten! # a call to #flatten instead would return a new array
["some", "thing"] + ["another", "thing"]
只是另一种方法。
[somearray, anotherarray].flatten
=> ["some", "thing", "another", "thing"]
详细阐述@Pilcrow的答案，对于大型数组唯一合适的答案是concat(+)，因为它速度快，并且在循环中操作时不会分配一个新对象来进行垃圾回收。
下面是基准:
require 'benchmark'
huge_ary_1 = Array.new(1_000_000) { rand(5_000_000..30_000_00) }
huge_ary_2 = Array.new(1_000_000) { rand(35_000_000..55_000_00) }
Benchmark.bm do |bm|
p '-------------------CONCAT ----------------'
bm.report { huge_ary_1.concat(huge_ary_2) }
p '------------------- PUSH ----------------'
bm.report { huge_ary_1.push(*huge_ary_2) }
end
结果:
user system total real
"-------------------CONCAT ----------------"
0.000000 0.000000 0.000000 ( 0.009388)
"------------------- PUSH ----------------"
example/array_concat_vs_push.rb:13:in `block (2 levels) in <main>': stack level too deep (SystemStackError)
正如你所看到的，当数组足够大时，使用push会抛出ERROR:堆栈级别太深(SystemStackError)。
a = ['a', 'b']
b = ['c', 'd']
arr = [a, b].flatten
这不会去除dups，但是
a|b
删除重复。
