如何向数组添加多个元素？

Question

I can easily add one element to an existing array:

arr = [1]
arr << 2
# => [1, 2]

How would I add multiple elements to my array?

I'd like to do something like arr << [2, 3] , but this adds an array to my array #=> [1, [2, 3]]

Answer 1

Using += operator:

arr = [1]
arr += [2, 3]
arr
# => [1, 2, 3]

Answer 2

Make use of .push

arr = [1]
arr.push(2, 3)
# => [1, 2, 3]

You can also .push() all elements of another array

second_arr = [2, 3]
arr.push(*second_arr)
# => [1, 2, 3]

But take notice! without the * it will add the second_array to arr .

arr.push(second_arr)
# => [1, [2, 3]]

---

Inferior alternative:

You could also chain the << calls:

arr = [1]
arr << 2 << 3
# => [1, 2, 3]

Answer 3

You can do also as below using Array#concat :

arr = [1]
arr.concat([2, 3]) # => [1, 2, 3]

Answer 4

There is several methods to achieve that:

array = [1, 2]

array += [3, 4] # => [1, 2, 3, 4]

# push: put the element at the end of the array
array.push([5, 6]) # =>  [1, 2, 3, 4, [5, 6]]
array.push(*[7, 8]) # => [1, 2, 3, 4, [5, 6], 7, 8]

array << 9 # => [1, 2, 3, 4, [5, 6], 7, 8, 9]

# unshift: put the element at the beginning of the array:
array.unshift(0) #=> [0, 1, 2, 3, 4, [5, 6], 7, 8, 9]

Some links:

• Array in Ruby 1.9.3: http://ruby-doc.org/stdlib-1.9.3/libdoc/csv/rdoc/Array.html
• Array in Ruby 2.0.0: http://www.ruby-doc.org/core-2.0.0/Array.html

Answer 5

just use .flatten

for example if you have this array

array = [1,2,3,4,5,6]

and you do this

array.push([123,456,789])
array.push([["abc","def"],["ghi","jkl"]])

your string would look something like

array = [[1,2,3,4,5,6],[123,456,789],[["abc","def"],["ghi","jkl"]]]

all you need to do is

array.flatten!

and now your array would like this

array = [1,2,3,4,5,6,123,456,789,"abc","def","ghi","jkl"]

Answer 6

Use Array#insert can add an array to any position:

a = [1, 2, 3]
b = [4,5,6]
b.insert(0, *a)
=> [1, 2, 3, 4, 5, 6]

Answer 7

One more, for building up an array with items n-times you can use the splat (AKA asterisk, * ):

arr = [true] * 4           # => [true, true, true, true]

You can also use the splat for repeating multiple elements:

arr = [123,'abc'] * 3      # => [123,'abc',123,'abc',123,'abc']

Of course, you can use any array operators with that, such as +:

arr = [true] * 3 + [false] # => [true, true, true, false]

I use that in conjunction with #sample to generate random weighted results:

arr.sample                 # => true 3 out of 4 times