在ruby中循环遍历多维数组答案

【问题标题】：Loop though multi-dimensional array in ruby在ruby中循环遍历多维数组
【发布时间】：2019-09-27 03:41:31
【问题描述】：

这是我遇到的问题。 “循环遍历多维数组并打印出数组中偶数项的完整信息（即多维数组中的第二个和第四个数组）”。我的任务是输出所有数据在应该是[1] [3]的偶数数组中，它将仅输出数组“derrick”和“andrew”中的所有信息。

kristopher = ["kris", "palos hills", "708-200", "green"]
derrick = ["D-Rock", "New York", "773-933", "green"]
willie = ["William", "Humbolt Park", "773-987", "Black"]
andrew = ["drew", "northside", "773-123","blue"]

friends = [kristopher, derrick, willie, andrew]

friends.each do |arr|
print arr [0..4]
end

#Output

["kris", "palos hills", "708-200", "green"]["D-Rock", "New York", "773-933", "green"]["William", "Humbolt Park", "773-987", "Black"]["drew", "northside", "773-123", "blue"]

【问题讨论】：

标签： ruby loops multidimensional-array

【解决方案1】：

类似这样的：

kristopher = ["kris", "palos hills", "708-200", "green"]
derrick = ["D-Rock", "New York", "773-933", "green"]
willie = ["William", "Humbolt Park", "773-987", "Black"]
andrew = ["drew", "northside", "773-123","blue"]

friends = [kristopher, derrick, willie, andrew]

(1...friends.length).step(2).each do |friendIndex|
    friend = friends[friendIndex]
    print friend 
end

【讨论】：

【解决方案2】：

您可以检查Enumerable#partition 和Enumerable#each_with_index，它们有助于根据元素索引的条件拆分数组。如果您使用Integer#even?，您可以在偶数和奇数索引之间进行分区（在这种情况下为+ 1）。

friends.partition.with_index { |_, i| (i + 1).even? }
#=> [[["D-Rock", "New York", "773-933", "green"], ["drew", "northside", "773-123", "blue"]], [["kris", "palos hills", "708-200", "green"], ["William", "Humbolt Park", "773-987", "Black"]]]

所以，对于你的情况，取第一个元素：

friends.partition.with_index { |_, i| (i + 1).even? }.first

或者你可以直接用Enumerable#select：

friends.select.with_index { |_, i| (i + 1).even? }

【讨论】：