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?
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? }
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?
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?
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"]
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[]?