ruby and watir学习之_Hash 类

http://www.cnblogs.com/zhangfei/archive/2010/07/28/1786929.html

 

 

ash类说明

函数名称	说明	示例
= =	判断两个 Hash 是否相等	h 1 = {"a" => 1, "c" => 2} h 2 = { "a" => 1, "c" => 2, 7 => 35 } h 1 == h2         » f alse
[ ]	返回指定键值对应的对象	h = { "a" => 100, "b" => 200 } h [ " a " ]   » 100 h["c"]   » n i l
[ ]=	向 Hash 添加记录	h = { "a" => 100, "b" => 200 } h [ " a " ] = 9 h["c"] = 4 h   » {"a"=>9, "b"=>200, "c"=>4}

clear	清空哈希表的内容. 返回 self.	h = { "a" => 100, "b" => 200 } h . clear         » {}
d efault	返回哈希表的默认值	h = { "a" => 100, "b" => 200 } h . d efault = "Go fish" h["a"]   » 100 h [ " z " ]   » " G o fish"
d elete	从词典中删除和键值相符的记录	h = { "a" => 100, "b" => 200 } h.delete("a")                    » 100 h.delete("z")                    » n i l h.delete("z") { |el| "#{el} not found" } » " z not found"
d elete_if	通过过程块来删除特定键值的记录	h = { "a" => 100, "b" => 200 } h . d elete_if {|key, value| key >= "b" } » {"a"=>100}
each	Hash 表的迭代操作，对表的每一个词对 进行迭代操作	h = { "a" => 100} h . each  {|key,  value|  print  key,  "  is " , v alue,"\n"}               » a is 100
each_key	对表的每一个键对进行迭代操作	h = { "a" => 100, "b" => 200 } h . each_key {|key| print key }        »    ab
each_value	针对 value 进行迭代操作	h = { "a" => 100, "b" => 200 } h . each_value {|value| print value } »    100200
empty?	判断哈希表是否为空，空则返回 true	{}.empty?       » t rue
f etch	如果能找到键值为 key 的 hash 值，则 返回 Hash 值； 如果找不到，则返回默认值或指定值； 如果默认值和指定值都找不到，抛异常	h = { "a" => 100, "b" => 200 } h.fetch("a")                   » 100 h.fetch("z", "go fish")  » "g o fish" h.fetch("k") » i n `fetch': key not found (IndexError)
h as_key?	判断是否存在相符的 key 值	h = { "a" => 100, "b" => 200 } h . h as_key?("a")   » t rue h.has_key?("z")   » f alse
key ？	h . key?("z")     » f alse
i n clude?	h .i n clude?("b")    » t rue
h as_value?	判断是否存在相符的 value 值	h = { "a" => 100, "b" => 200 } h . h as_value?(100)  » t r u e h.has_value?(999)  » f alse
v alue?	h . v alue?(100)  » t rue h.value?(999)  » f alse
i nd ex	返回给定值的键值，未找到返 nil	h = { "a" => 100, "b" => 200 } h .i nd e x(200)  » " b " h.index(999)  » n i l
i nd exes	返回一系列给定的键值对应值组成的数 组	h = { "a" =>100, "b" =>200, "c" =>300 } h .i nd e xes("a", "c")         » [ 100,300] h .i nd e xes("a","z")           » [ 100,nil]

i nd i ces		h .i nd e xes("a", "c")         » [ 100,300] h.indexes("a", "z")      » [100,nil]
i n v ert	将元素值和索引互换,返回变换后的哈 希表. 注意: 若原哈希表中若干不同的索引对 应相同的元素值时, 其变换结果将无法 预测.	h = { "n" => 100,"m" => 100,"y" => 300} h .i n v ert       » {300=>"y",100=>"n"}
keys	返回一个包含所有 key 的数组.	h = { "a" => 100, "b" => 200 } h . keys                 » [ " a", "b"]
v alues	返回一个包含所有 vakue 的数组.	h = { "a" => 100,"b" => 200,"c" => 300 } h . v alues          » [ 100, 200, 300]
l ength	返回词典中元素的个数	h = { "d" =>100, "a"=> 200, "v" => 300} h .l ength          » 3 h. size             » 3
size
rehash	重新计算索引对应的哈希表值。 当与索引对应的哈希表值发生变化时， 若不使用该方法来重新计算的话，将无 法取出与索引对应的哈希表值。	a = [ "a", "b" ] c = [ "c", "d" ] h = { a => 100, c => 300 } a[0] = "z" h.rehash » {["z", "b"]=>100, ["c", "d"]=>300} h [ a]   » 100
replace	以另外一张 Hash 表的内容来替换当前 Hash 表的内容	h = {"a" =>100, "b" =>200 } h . replace({ "c" => 300, "d" => 400 }) » {"c"=>300, "d"=>400}
shift	删除一个哈希表元素后 再以[key,value]数组的形式将其返回	h = { 1 => "a", 2 => "b", 3 => "c" } h . shift   » [ 1, "a"] h   » {2=>"b", 3=>"c"}
sort	对 Hash 进行排序 按键值从小到大排序	h = { "b" => 30, "a" => 20, "c" => 10  } h.sort   » [[ " a " , 20], ["b", 30], ["c", 10]] h.sort {|a,b| a[1]<=>b[1]} » [[ " c", 10], ["a", 20], ["b", 30]]
to_a	把 Hash 表转换为数组 数组按 Hash 表的键值从小到大排序	h = {"c" =>300,"a" =>100,"d" =>400} »    [[ " a", 100], ["c", 300], ["d", 400]]
t o_ s	把 Hash 表转换为字符串	h = { "c" => 300, "a" => 100, "d" => 400} h .t o_ s          » " a100c300d400"
u p d ate	用一张 Hash 表去更新另外张 Hash 表	h 1 = { "a" => 100, "b" => 200 } h2 = { "b" => 254, "c" => 300 } h1.update(h2) » {"a"=>100, "b"=>254, "c"=>300}