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]
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
如果新数据可以是数组或标量,并且如果它是数组,则希望防止新数据嵌套,splat操作符非常棒!它为标量返回一个标量,为数组返回一个已解压的参数列表。
1.9.3-p551 :020 > a = [1, 2]
=> [1, 2]
1.9.3-p551 :021 > b = [3, 4]
=> [3, 4]
1.9.3-p551 :022 > c = 5
=> 5
1.9.3-p551 :023 > a.object_id
=> 6617020
1.9.3-p551 :024 > a.push *b
=> [1, 2, 3, 4]
1.9.3-p551 :025 > a.object_id
=> 6617020
1.9.3-p551 :026 > a.push *c
=> [1, 2, 3, 4, 5]
1.9.3-p551 :027 > a.object_id
=> 6617020
其他回答
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"]
Somearray = ["some", "thing"]
Anotherarray = ["another", "thing"]
Somearray + anotherarray
你可以使用+运算符!
irb(main):001:0> a = [1,2]
=> [1, 2]
irb(main):002:0> b = [3,4]
=> [3, 4]
irb(main):003:0> a + b
=> [1, 2, 3, 4]
你可以在这里阅读关于数组类的所有内容: http://ruby-doc.org/core/classes/Array.html
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)。
只是另一种方法。
[somearray, anotherarray].flatten
=> ["some", "thing", "another", "thing"]