【转载】ruby 中数组函数示例，1
| 函数名称 | 说明 | 示例 |
| & | 数组与，返回两数组的交集 | [1,2] & [2,3] =>[2] |
| * | 复制数组n次 | [1,2]*2 => [1,2,1,2] |
| + | 返回两数组的并集，但不排除重复元素 | [1,2]+[2,3] =>[1,2,2,3] |
| << | 追加元素，但不排除重复元素 | [1,2]<<[2,3] => [1,2,2,3] |
| | | 追加元素，但排除重复元素 | [1,2] | [2,3] => [1,2,3] |
| - | 返回第一个数组与第二个数组不同的元素 | [1,2]-[2,3] => [1] |
| <=> | 比较数组 | [1,2]<=>[2,3] =>flase |
| == | 比较数组，若所有元素均相等时返回真 | [1,2]==[2,1] =>flase |
| assoc | 从数组的每个元素中寻找指定对象 | [1,2],[3,4]].assoc(2)=> [1,2] |
| at | 找到数组的第N个元素
负数表示逆向查找 | ["a","b","c","d","e"].at(0) => "a"
["a","b","c","d","e"].at(-1) => "e" |
| clear | 删除数组中的所有元素 | ["a","b","c","d","e"]. Clear |
| collect
collect！ | 用一个过程块对数组的每个元素进行处理 | ["a","b","c","d"].collect {|x| x + "!" }
=> ["a!", "b!", "c!", "d!"] |
| compact
compact! | 删除值为nil的元素后生成新数组并返回它 | ["a",nil,"b",nil,"c",nil].compact
=> ["a", "b", "c"] |
| count | 统计数组中某元素的个数 | [1,2,3,4,1,3,1,6].count(1) =>3 |
| delete | 删除元素，如果元素重复，全部删除 | a = [ "a", "b", "b", "b", "c" ]
a.delete("b") puts a => ["a","c"] |
| delete_at | 删除pos所指位置的元素并返回它。若pos超出数 组范围则返回nil | a = %w( ant bat cat dog )
a.delete_at(2) ? "cat" a=> ["ant", "bat", "dog"] a.delete_at(99) => nil |
| delete_if | 根据条件删除 | a = [ "a", "b", "c" ]
a.delete_if {|x| x >= "b" } => ["a"] |
| each | 对数组的每个元素按值进行迭代操作
查寻方法find，也有：list = ['a','b','c'] list.find{|x| x=='c'} | a = [ "a", "b", "c" ]
a.each {|x| print x, " -- " } => "a -- b -- c --" |
| each_index | 对数组的每个元素按索引进行迭代操作 | a = [ "a", "b", "c" ]
a.each_index {|x| print x, " -- " } => "0 -- 1 -- 2 --" |
| empty? | 判断数组是否为空，为空则返回真 | [].empty?=> true |
| eql！ | 比较两数组是否相等 | ["a","b","c"].eql?(["a","b","c"]) => true |
| fill | 填充数组 | ["a","b","c","d"].fill("x")
=> ["x","x","x","x"] ["a","b","c","d"].fill("z", 2, 2) => ["x", "x", "z", "z"] |
| first | 返回数组的首元素。若没有首元素则返回nil | [ "q", "r", "s", "t" ].first => "q" |
| last | 返回数组末尾的元素。若数组为空时，返回nil | ["w","x","y","z"].last => "z" |
| include? | 判断数组中是否包含元素 | a = [ "a", "b", "c" ]
a.include?("b") => true a.include?("z") => false |
| index | 返回数组中第一个==val的元素的位置 | a = [ "a", "b", "c" ]
a.index("b") => 1 a.index("z") => nil |
| indexes | 以数组形式返回其索引值与各参数值相等的元素 | a = [ "a", "b", "c", "d", "e", "f", "g" ]
a.indexes(0, 2, 4) => ["a", "c", "e"] a.indexes( 2, 4, 12)=> [ "c", "e", nil] |
| insert | 在索引为nth的元素前面插入第2参数以后的值 | ary = %w(foo bar baz)
ary.insert 2,'a','b' p ary => ["foo", "bar", "a", "b", "baz"] |
| join | 将数组元素按一定的分隔符连接起来 | [ "a", "b", "c" ].join=> "abc"
[ "a", "b", "c" ].join("-") => "a-b-c" |
| length
size | 返回数组长度。若数组为空则返回0 | [1,2,3].length => 3
[1,2,3].size => 3 |
| nitems | 返回非nil元素的个数 | [ 1, nil, 3, nil, 5 ].nitems => 3 |
| pop | 删除末尾元素并返回它。若数组为空则返回nil | a = [ "a", "m", "z" ]
a.pop => "z" p a => ["a", "m"] |
| push | 添加新元素 | ["a","b"].push(['1','2'])
=>["a", "b", ["1", "2"]] |
| rassoc | 遍历数组每个元素（元素必须是数组），匹配索引为1的值是否与查找的字符相等，返回第一个相等的元素 | a = [[15,1], [25,2], [35,2]]
p a.rassoc(2) => [25, 2] |
| replace | 替换数组元素 | a = ["a","b"]
a.replace(["x","y","z"]) p a =>["x", "y", "z"] |
| reverse
reverse！ | 将所有元素以逆序重新排列生成新数组并返回它 | ["a","b","c" ].reverse=> ["c", "b", "a"] |
| rindex | 返回最后一个值相等的元素的索引值 | a = [ "a","b","b","b","c"]
a.rindex("b") => 3 |
| shift | 删除数组的首元素并返回它。剩余元素依次提前。若数组为空返回nil | args = ["-m","-q","filename"]
args.shift => "-m" args => ["-q", "filename"] |
| sort
sort! | 从小到大排序 | a = [ "d", "a", "e", "c", "b" ]
a.sort => ["a", "b", "c", "d", "e"] |
| uniq
uniq！ | 删除数组中的重复元素后生成新数组并返回它 | a = [ "a", "a", "b", "b", "c" ]
a.uniq => ["a", "b", "c"] |
| unshift | 在数组第一个元素前添加元素 | a = [ "b", "c", "d" ]
a.unshift("a") => ["a", "b", "c", "d"] |
| to_s | 将数组的所有元素连接成字符串 | ["a","e","i","o"].to_s => "aeio" |
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