如何从数组中删除空白元素？

Question

我有以下数组

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这样的方法没有循环？

Answer 1

有很多方法可以做到这一点,一个是 reject

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

您也可以使用reject!,它将cities在适当的位置进行修改.cities如果它拒绝某些东西,或者nil如果没有拒绝,它将返回作为其返回值.如果你不小心,这可能是一个问题(感谢ninja08在评论中指出这一点).

Answer 2

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

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

Answer 3

这对我有用:

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

输出:

[1, 2, "hello"]

Answer 4

在我的项目中,我使用delete:

cities.delete("")

Answer 5

当我想整理这样的数组时,我使用:

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

这将删除所有空白或零元素.

Answer 6

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"]

Answer 7

试试这个:

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

Answer 8

用途reject:

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

Answer 9

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

你想使用的原因blank?在empty?是空白识别零,空字符串,和空白.例如:

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

还会回来:

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

并呼吁empty?对" "将返回false,这你可能想true.

注意:blank?只能通过Rails访问,Ruby仅支持empty?.

Answer 10

compact_blank (Rails 6.1+)

如果您使用Rails（或独立ActiveSupport），从 version 开始6.1，有一种compact_blank方法可以blank从数组中删除值。

它Object#blank?在引擎盖下用于确定项目是否为空白。

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

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

这是文档的链接和相关 PR的链接。

还可以使用破坏性变体。见Array#compact_blank!。

如果您只需要删除nil值，

请考虑使用 Ruby 内置Array#compact和Array#compact!方法。

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

Answer 11

要删除 nil 值，请执行以下操作：

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

要删除空字符串：

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

要删除 nil 和空字符串：

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

Answer 12

已经有很多答案,但如果您在Rails世界中,这是另一种方法:

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

Answer 13

这是实现这一目标的另一种方法

我们可以使用presence与select

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

cities.select(&:presence)

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

Answer 14

如果您的数组中有混合类型,这是一个解决方案:

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

解:

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

输出:

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

Answer 15

你可以试试看

 cities.reject!(&:empty?)