我在RailsCast中找到了这段代码:
def tag_names
@tag_names || tags.map(&:name).join(' ')
end
什么是(&:name)中map(&:name)意味着什么？
在Ruby中有没有办法将所有数组元素组合成一个字符串？
示例数组:
@arr = ['<p>Hello World</p>', '<p>This is a test</p>']
示例输出:
<p>Hello World</p><p>This is a test</p>
我有一个数组:
int_array = [11,12]
我需要把它转换成
str_array = ['11','12']
我是这项技术的新手
我正在学习rails并遵循这个主题.我坚持使用这种to_proc方法.我认为符号只是字符串的替代品(它们就像字符串,但在内存方面更便宜).如果还有其他我想念的符号,那么请告诉我.请以简单的方式解释什么to_proc方法和用途.
是否有一种在Ruby中编写每个块的单行方法？
cats.each do |cat|
cat.name
end
我正在尝试缩短项目中的代码量.我正在使用Ruby 1.9.2.
谢谢!
可能重复:
map(&:name)在Ruby中意味着什么？
我遇到了一个代码片段,其中包含以下内容
a.each_slice(2).map(&:reverse)
我不知道&:运营商的功能.这是如何运作的？
我已经看过好几次,但我无法弄清楚如何使用它们.镐说这些是特殊的快捷方式,但我无法找到语法描述.
我在这样的背景下见过他们:
[1,2,3].inject(:+)
以计算总和为例.
我正在阅读Stackoverflow并偶然发现以下代码
array.map(&:to_i)
好的,很容易看出这段代码的作用,但我想了解更多关于&:我以前从未见过的构造.
不幸的是,我能想到的只是"lambda",而不是.谷歌告诉我Ruby中的lambda语法是->->(x,y){ x * y }
所以&:除了调用单一方法之外,任何人都知道神秘是什么以及它能做什么？
大多数ruby开发人员都知道如何通过执行以下操作来节省一些按键:
array.map(&:methodname)
而不是
array.map {|x| x.methodname }
有没有什么方法可以应用类似的&:methodname快捷方式来调用哈希数组中的"方法"(通过键调用的值)？
在我的情况下,它的JSON api结果以60个批量返回,作为源自JSON的哈希数组.我试图这样做,但没有成功:
array.map(&:"keyname")
但是没有成功,抛出一个NoMethodError并且说Hash没有'keyname'方法,这是合理的我猜.我想知道是否有一些神奇的子弹来模仿这个&:...红宝石家伙已经解决过的哈希的快捷方式.
这是实际的JSON响应之一,我认为仅限于5个结果
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假设我有一个从1到10的未排序数组,如下所示......
a = ["3", "5", "8", "4", "1", "2", "9", "10", "7", "6"]
如果我在这个数组上使用sort方法,它会返回这个...
a.sort = ["1", "10", "2", "3", "4", "5", "6", "7", "8", "9"]
如你所见,10出现在2之前,这是不正确的.如何对这些数字进行排序以使10正确显示？
编辑:大家好,谢谢大家的回复.我应该更好地解释我的问题.我需要排序的数组是电子商务价格表.所以阵列如下......
a = ["0-10", "11-20", "21-30", "31-40" etc.]
所以字符串不能转换为整数.我写这个问题的时候应该这样说.我不认为修复会有太大的不同.我的错,我为做出这个假设而道歉!我怎么能排序这个数组？谢谢!