我有下面的数组

cities = ["Kathmandu", "Pokhara", "", "Dharan", "Butwal"]

我想从数组中删除空白元素,并希望得到以下结果:

cities = ["Kathmandu", "Pokhara", "Dharan", "Butwal"]

有没有像compact这样不需要循环的方法?


有很多方法可以做到这一点,其中之一是拒绝

noEmptyCities = cities.reject { |c| c.empty? }

你也可以用reject!,这将改变城市的位置。如果拒绝某项,它将返回cities作为返回值,如果没有拒绝,则返回nil。如果你不小心,这可能是一个陷阱(感谢ninja08在评论中指出这一点)。


使用拒绝:

>> cities = ["Kathmandu", "Pokhara", "", "Dharan", "Butwal"].reject{ |e| e.empty? }
=> ["Kathmandu", "Pokhara", "Dharan", "Butwal"]

 cities = ["Kathmandu", "Pokhara", "", "Dharan", "Butwal"].delete_if {|c| c.empty? } 

试试这个:

puts ["Kathmandu", "Pokhara", "", "Dharan", "Butwal"] - [""]

已经有很多答案了,但如果你在Rails世界里,这里有另一种方法:

 cities = ["Kathmandu", "Pokhara", "", "Dharan", "Butwal"].select &:present?

在我的项目中,我使用delete:

cities.delete("")

1.9.3p194 :001 > ["", "A", "B", "C", ""].reject(&:empty?)

=> ["A", "B", "C"]

如果你的数组中有混合类型,下面是一个解决方案:

[nil,"some string here","",4,3,2]

解决方案:

[nil,"some string here","",4,3,2].compact.reject{|r| r.empty? if r.class == String}

输出:

=> ["some string here", 4, 3, 2]

当我想整理一个这样的数组时,我使用:

["Kathmandu", "Pokhara", "", "Dharan", "Butwal"] - ["", nil]

这将删除所有空白或nil元素。


cities.reject! { |c| c.blank? }

为什么要用空白?在空的吗?blank可以识别nil,空字符串和空白。例如:

cities = ["Kathmandu", "Pokhara", " ", nil, "", "Dharan", "Butwal"].reject { |c| c.blank? }

仍然会返回:

["Kathmandu", "Pokhara", "Dharan", "Butwal"]

叫空?On " "将返回false,您可能希望它为true。

注:空白?只能通过Rails访问,Ruby只支持空?


以下是对我有效的方法:

[1, "", 2, "hello", nil].reject(&:blank?)

输出:

[1, 2, "hello"]

你可以试试这个

 cities.reject!(&:empty?)

这里还有一种方法可以实现这一点

我们可以使用presence和select

cities = ["Kathmandu", "Pokhara", "", "Dharan", nil, "Butwal"]

cities.select(&:presence)

["Kathmandu", "Pokhara", "Dharan", "Butwal"]

最明确的

cities.delete_if(&:blank?)

这将删除nil值和空字符串("")值。

例如:

cities = ["Kathmandu", "Pokhara", "", "Dharan", "Butwal", nil]

cities.delete_if(&:blank?)
# => ["Kathmandu", "Pokhara", "Dharan", "Butwal"]

最短路径城市。select(&:present?)


使用严格的join & split更新

cities = ["Kathmandu", "Pokhara", "", "Dharan", "Butwal"]
cities.join(' ').split

结果将是:

["Kathmandu", "Pokhara", "Dharan", "Butwal"]

注意:这对有空间的城市不起作用


另一种方法:

> ["a","b","c","","","f","g"].keep_if{|some| some.present?}
=> ["a","b","c","f","g"]

compact_blank (Rails 6.1+)

如果您正在使用Rails(或独立的ActiveSupport),从6.1版开始,将有一个compact_blank方法从数组中删除空白值。

它使用Object#blank?用于确定一个项目是否为空白。

["Kathmandu", "Pokhara", "", "Dharan", nil, "Butwal"].compact_blank
# => ["Kathmandu", "Pokhara", "Dharan", "Butwal"]

[1, "", nil, 2, " ", [], {}, false, true].compact_blank
# => [1, 2, true]

这里有一个文档链接和一个相关PR链接。

破坏性的变种也是可用的。# compact_blank !看到数组。


如果您使用的是较旧版本的Rails,请检查compact_blank内部实现。

反向移植并不复杂。

def compact_blank
  reject(&:blank?)
end

如果你只需要删除nil值,可以考虑使用Ruby内置的Array#compact和Array#compact!方法。

["a", nil, "b", nil, "c", nil].compact
# => ["a", "b", "c"]

纯Ruby:

values = [1,2,3, " ", "", "", nil] - ["", " ", nil]
puts values # [1,2,3]

删除空值:

 ['a', nil, 'b'].compact  ## o/p =>  ["a", "b"]

删除空字符串:

   ['a', 'b', ''].select{ |a| !a.empty? } ## o/p => ["a", "b"]

删除空字符串和空字符串:

['a', nil, 'b', ''].select{ |a| a.present? }  ## o/p => ["a", "b"]

更新在拒绝和拒绝!

注意:我遇到了这个问题,并在irb控制台上用ruby-3.0.1检查了这些方法。我也检查了ruby文档,但没有提到这一点。我不确定从哪个ruby版本 变化就在那里。非常感谢来自社区的任何帮助。

在ruby-3.0.1中,我们可以使用reject或reject!

cities = ["Kathmandu", "Pokhara", "", "Dharan", "Butwal"]
cities.reject{ |e| e.empty? }
=> ["Kathmandu", "Pokhara", "Dharan", "Butwal"]

或简写

cities.reject(&:empty?)
=> ["Kathmandu", "Pokhara", "Dharan", "Butwal"]

无论我们是否有一个空值,两者都会返回[]?