Let's say I have an array
假设有一个数组
array = [1,2,3,4,5]
How do I compare the first with the second value, the second with the third etc.
如何比较第一个值和第二个值，第二个值和第三个值等等。
The only thing I could come up with is this (which is rather ugly)
我唯一能想到的就是这个(相当难看)
compared = array.each_with_index.map do |a,i|
array[i+1].nil? ? nil : array[i] - array[i + 1]
end
compared.compact # to remove the last nil value
What I want is
我想要的是
[-1, -1, -1, -1]
Is there a nice "ruby way" of achieving this? without using all the ugly array[i] and array[i+1] stuff.
有一种很好的“ruby方法”来实现这一点吗?不需要使用所有难看的数组[i]和数组[i+1]之类的东西。
2 个解决方案
#1
9
Using Enumerable#each_cons:
使用# each_cons可列举的:
array = [1,2,3,4,5]
array.each_cons(2).map { |a,b| a - b }
# => [-1, -1, -1, -1]
#2
1
You can also use Enumerable#inject：
您也可以使用可列举的#注入:
a = [1,2,3,4,5]
b = []
a.inject{|i,j| b<< i-j; j}
p b
result：
结果:
[-1, -1, -1, -1]
#1
9
Using Enumerable#each_cons:
使用# each_cons可列举的:
array = [1,2,3,4,5]
array.each_cons(2).map { |a,b| a - b }
# => [-1, -1, -1, -1]
#2
1
You can also use Enumerable#inject：
您也可以使用可列举的#注入:
a = [1,2,3,4,5]
b = []
a.inject{|i,j| b<< i-j; j}
p b
result：
结果:
[-1, -1, -1, -1]