blocks|key|1193949|text|rows,+cols+=+x,y++#+your+values
grid+=+Array.new(rows)+{+Array.new(cols)+}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1193950|至于访问元素，这篇文章非常适合用您想要的方式逐步封装数组：|unstyled|1193951|How+to+ruby+array|offset|length|1193952|entityMap|0|LINK|mutability|MUTABLE|url|http://www.ehow.com/how_2091651_create-multidimensional-array-ruby.html^0|0|0|0|H|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|T|8|@]|9|@]|A|$]]|$1|G|3|H|5|F|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|F|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

<pre><code>rows, cols = x,y # your values
grid = Array.new(rows) { Array.new(cols) }
</code></pre>

As for accessing elements, this article is pretty good for step by step way to encapsulate an array in the way you want:

<a href="http://www.ehow.com/how_2091651_create-multidimensional-array-ruby.html" rel="noreferrer">How to ruby array</a>

blocks|key|1409330|text|x.transpose[6][3..8]或x[3..8].map+{%7Cr%7C+r+[6]}会给你想要的。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1409331|示例：|1409332|a+=+[+[1,++2,++3,++4,++5],
++++++[6,++7,++8,++9,++10],
++++++[11,+12,+13,+14,+15],
++++++[21,+22,+23,+24,+25]
++++]

#a[1..2][2]++->+[8,13]
puts+a.transpose[2][1..2].inspect+++#+[8,13]
puts+a[1..2].map+{%7Cr%7C+r[2]}.inspect++#+[8,13]|code-block|syntax|javascript|1409333|entityMap^0|0|K|L|N|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|T|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|U|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|V|8|@]|D|@]|E|$]]]|N|$]]

<code>x.transpose[6][3..8]</code> or <code>x[3..8].map {|r| r [6]}</code> would give what you want.

Example:

<pre><code>a = [ [1, 2, 3, 4, 5],
 [6, 7, 8, 9, 10],
 [11, 12, 13, 14, 15],
 [21, 22, 23, 24, 25]
 ]

#a[1..2][2] -&gt; [8,13]
puts a.transpose[2][1..2].inspect # [8,13]
puts a[1..2].map {|r| r[2]}.inspect # [8,13]
</code></pre>

blocks|key|1409431|text|2维Arrays的实现方式存在一些问题。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1409432|a=+[[1,2],[3,4]]
a[0][2]=+5+#+works
a[2][0]=+6+#+error|code-block|syntax|javascript|1409433|作为Array的Hash|1409434|对于多维Arrays，我更喜欢使用Hashes|1409435|a=+Hash.new
a[[1,2]]=+23
a[[5,6]]=+42|1409436|这样做的好处是，您不必手动创建列或行。插入散列几乎就是O(1)，所以只要你的Hash不变得太大，这里就没有什么缺点。|1409437|您甚至可以为所有未指定的元素设置默认值|1409438|a=+Hash.new(0)|1409439|现在我们来看看如何获得子数组|1409440|(3..5).to_a.product([2]).collect+{+%7Cindex%7C+a[index]+}
[2].product((3..5).to_a).collect+{+%7Cindex%7C+a[index]+}|1409441|(a..b).to_a以O(n)的速度运行。从Hash中检索一个元素几乎是O(1)，因此收集的运行时间几乎是O(n)。没有办法让它比O(n)更快，因为复制n个元素总是O(n)。|1409442|当Hashes变得太大时，可能会出现问题。因此，如果我知道我的数据量越来越大，那么在实现这样的多维Array时，我会三思而后行。|1409443|entityMap|0|LINK|mutability|MUTABLE|url|http://en.wikipedia.org/wiki/Time_complexity#Table_of_common_time_complexities^0|2|6|0|0|2|5|8|4|0|4|6|H|6|0|0|12|4|R|4|0|0|0|0|0|0|0|B|N|4|0|1|6|1D|5|0^^$0|@$1|2|3|4|5|6|7|1C|8|@$9|1D|A|1E|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|1F|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|1G|8|@$9|1H|A|1I|B|C]|$9|1J|A|1K|B|C]]|D|@]|E|$]]|$1|M|3|N|5|6|7|1L|8|@$9|1M|A|1N|B|C]|$9|1O|A|1P|B|C]]|D|@]|E|$]]|$1|O|3|P|5|H|7|1Q|8|@]|D|@]|E|$I|J]]|$1|Q|3|R|5|6|7|1R|8|@$9|1S|A|1T|B|C]]|D|@$9|1U|A|1V|1|1W]]|E|$]]|$1|S|3|T|5|6|7|1X|8|@]|D|@]|E|$]]|$1|U|3|V|5|H|7|1Y|8|@]|D|@]|E|$I|J]]|$1|W|3|X|5|6|7|1Z|8|@]|D|@]|E|$]]|$1|Y|3|Z|5|H|7|20|8|@]|D|@]|E|$I|J]]|$1|10|3|11|5|6|7|21|8|@$9|22|A|23|B|C]|$9|24|A|25|B|C]]|D|@]|E|$]]|$1|12|3|13|5|6|7|26|8|@$9|27|A|28|B|C]|$9|29|A|2A|B|C]]|D|@]|E|$]]|$1|14|3|-4|5|6|7|2B|8|@]|D|@]|E|$]]]|15|$16|$5|17|18|19|E|$1A|1B]]]]

There are some problems with 2 dimensional <code>Arrays</code> the way you implement them.

<pre><code>a= [[1,2],[3,4]]
a[0][2]= 5 # works
a[2][0]= 6 # error
</code></pre>

<h1><code>Hash</code> as <code>Array</code></h1>

I prefer to use <code>Hashes</code> for multi dimensional <code>Arrays</code>

<pre><code>a= Hash.new
a[[1,2]]= 23
a[[5,6]]= 42
</code></pre>

This has the advantage, that you don't have to manually create columns or rows. Inserting into hashes is almost <a href="http://en.wikipedia.org/wiki/Time_complexity#Table_of_common_time_complexities" rel="noreferrer">O(1)</a>, so there is no drawback here, as long as your <code>Hash</code> does not become too big.

You can even set a default value for all not specified elements

<pre><code>a= Hash.new(0)
</code></pre>

So now about how to get subarrays

<pre><code>(3..5).to_a.product([2]).collect { |index| a[index] }
[2].product((3..5).to_a).collect { |index| a[index] }
</code></pre>

<code>(a..b).to_a</code> runs in O(n). Retrieving an element from an <code>Hash</code> is almost O(1), so the collect runs in almost O(n). There is no way to make it faster than O(n), as copying n elements always is O(n).

<code>Hashes</code> can have problems when they are getting too big. So I would think twice about implementing a multidimensional <code>Array</code> like this, if I knew my amount of data is getting big.

blocks|key|1194159|text|你没有陈述你的实际目标，但这可能会有所帮助：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1194160|require+'matrix'++#+bundled+with+Ruby
m+=+Matrix[
+[1,+2,+3],
+[4,+5,+6]
]

m.column(0)+#+==>+Vector[1,+4]|code-block|syntax|javascript|1194161|(向量的作用类似于数组)|1194162|或者，根据您的需要使用类似的符号：|1194163|m.minor(0..1,+2..2)+#+=>+Matrix[[3],+[6]]|1194164|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|D|7|S|8|@]|9|@]|A|$E|F]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

You didn't state your actual goal, but maybe this can help:

<pre><code>require 'matrix' # bundled with Ruby
m = Matrix[
 [1, 2, 3],
 [4, 5, 6]
]

m.column(0) # ==&gt; Vector[1, 4]
</code></pre>

(and Vectors acts like arrays)

or, using a similar notation as you desire:

<pre><code>m.minor(0..1, 2..2) # =&gt; Matrix[[3], [6]]
</code></pre>

blocks|key|1194212|text|这是一个3D数组的例子|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1194213|class+Array3D
+++def+initialize(d1,d2,d3)
++++@data+=+Array.new(d1)+{+Array.new(d2)+{+Array.new(d3)+}+}
+++end

++def+[](x,+y,+z)
++++@data[x][y][z]
++end

++def+[]=(x,+y,+z,+value)
++++@data[x][y][z]+=+value
++end
end|code-block|syntax|javascript|1194214|您可以像访问任何其他Ruby数组一样访问每个数组的子部分。@data0..28..10+=0等|1194215|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Here's a 3D array case

<pre><code>class Array3D
 def initialize(d1,d2,d3)
 @data = Array.new(d1) { Array.new(d2) { Array.new(d3) } }
 end

 def [](x, y, z)
 @data[x][y][z]
 end

 def []=(x, y, z, value)
 @data[x][y][z] = value
 end
end
</code></pre>

You can access subsections of each array just like any other Ruby array.
@data[0..2][3..5][8..10] = 0 
etc

blocks|key|1409685|text|下面是简单的版本|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1409686|+#one
+a+=+[[0]*10]*10

+#two
row,+col+=+10,+10
a+=+[[0]*row]*col|code-block|syntax|javascript|1409687|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Here is the simple version

<pre><code> #one
 a = [[0]*10]*10

 #two
row, col = 10, 10
a = [[0]*row]*col
</code></pre>

blocks|key|1194291|text|a+=+Array.new(Array.new(4))

0.upto(a.length-1)+do+%7Ci%7C
++0.upto(a.length-1)+do+%7Cj%7C
++++a[i[j]]+=+1
++end
end

0.upto(a.length-1)+do+%7Ci%7C
++0.upto(a.length-1)+do+%7Cj%7C
++++print+a[i[j]]+=+1+#It's+not+a[i][j],+but+a[i[j]]
++end
++puts+"\n"
end|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1194292|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>a = Array.new(Array.new(4))

0.upto(a.length-1) do |i|
 0.upto(a.length-1) do |j|
 a[i[j]] = 1
 end
end

0.upto(a.length-1) do |i|
 0.upto(a.length-1) do |j|
 print a[i[j]] = 1 #It's not a[i][j], but a[i[j]]
 end
 puts "\n"
end
</code></pre>

blocks|key|1194367|text|我很确定这可以很简单|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1194368|2.0.0p247+:032+>+list+=+Array.new(5)

+=>+[nil,+nil,+nil,+nil,+nil]+

2.0.0p247+:033+>+list.map!{+%7Cx%7C+x+=+[0]+}

+=>+[[0],+[0],+[0],+[0],+[0]]+

2.0.0p247+:034+>+list[0][0]

++=>+0|code-block|syntax|javascript|1194369|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I'm quite sure this can be very simple

<pre><code>2.0.0p247 :032 &gt; list = Array.new(5)

 =&gt; [nil, nil, nil, nil, nil] 

2.0.0p247 :033 &gt; list.map!{ |x| x = [0] }

 =&gt; [[0], [0], [0], [0], [0]] 

2.0.0p247 :034 &gt; list[0][0]

 =&gt; 0
</code></pre>

blocks|key|1409820|text|这里有一个创建"2D“数组的简单方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1409821|2.1.1+:004+>+m=Array.new(3,Array.new(3,true))

=>+[[true,+true,+true],+[true,+true,+true],+[true,+true,+true]]|code-block|syntax|javascript|1409822|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Here is an easy way to create a "2D" array.

<pre><code>2.1.1 :004 &gt; m=Array.new(3,Array.new(3,true))

=&gt; [[true, true, true], [true, true, true], [true, true, true]]
</code></pre>

I wonder if there's a possibility to create a two dimensional array and to quickly access any horizontal or vertical sub array in it? 

I believe we can access a horizontal sub array in the following case:

<pre><code>x = Array.new(10) { Array.new(20) }

x[6][3..8] = 'something'
</code></pre>

But as far as I understand, we cannot access it like this:

<pre><code>x[3..8][6]
</code></pre>

How can I avoid or hack this limit?

Create two-dimensional arrays and access sub-arrays in Ruby

我想知道是否有可能创建一个二维数组并快速访问其中的任何水平或垂直子数组？我相信在下面的情况下我们可以访问一个水平子数组：x = Array.new(10) { Array.new(20) }x[6][3..8] = 'something'但据我所知，我们不能这样访问它：x[3..8][6]我如何避免或破解这一限制？

问在Ruby中创建二维数组和访问子数组
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