I have several arrays of various lengths, each with a 2-item array within it. For example:
我有几个不同长度的数组,每个数组都有两个条目。例如:
[["12:00", 7.0], ["01:00", 3.3], ["02:00", 11.9], ["03:00", 56.5]]
or
或
[["12:00", 44.3], ["01:00", 2.25], ["02:00", 2.44], ["03:00", 46.11], ["04:00", 8.9], ["05:00", 18.187]]
I want to loop through, and add the corresponding elements of each array, into a new array. The output array will be the length of the longest array we're adding together.
我要循环,并将每个数组的相应元素添加到一个新的数组中。输出数组将是我们加在一起的最长数组的长度。
So the two arrays above summed together would output the following:
所以上面两个数组相加会得到如下结果:
[["12:00", 51.3], ["01:00", 5.55], ["02:00", 14.34], ["03:00", 102.61], ["04:00", 8.9], ["05:00", 18.187]]
I don't think I can use reduce()
or inject()
since I don't want to collapse the array, nor is the array a simple array of elements.
我不认为可以使用reduce()或inject(),因为我不想折叠数组,数组也不是简单的元素数组。
I really have no idea how I might approach this problem.
我真的不知道该如何处理这个问题。
2 个解决方案
#1
4
You can do it in one line with Hash.merge. Use a block to sum the values during the merge.
你可以在一行中使用hash。merge。在合并期间使用块来求和值。
def sum_arrays(a, b)
Hash[a].merge(Hash[b]){|k, i, j| i + j}.to_a
end
Output:
输出:
a = [["12:00", 7.0], ["01:00", 3.3], ["02:00", 11.9], ["03:00", 56.5]]
b = [["12:00", 44.3], ["01:00", 2.25], ["02:00", 2.44], ["03:00", 46.11], ["04:00", 8.9], ["05:00", 18.187]]
sum_arrays(a,b)
=> [["12:00", 51.3], ["01:00", 5.55], ["02:00", 14.34], ["03:00", 102.61], ["04:00", 8.9], ["05:00", 18.187]]
To sum more than two arrays, add one more line:
若要将两个以上的数组相加,请再加一行:
def sum_many_arrays(*a)
a.reduce{|s, i| sum_arrays(s, i)}
end
Output:
输出:
sum_many_arrays([[:a,1],[:b,2]],[[:a,2],[:b,2],[:c,1]],[[:a,5],[:b,2]])
=> [[:a, 8], [:b, 6], [:c, 1]]
#2
0
I recommend @Oleg's approach, but there's always another way:
我推荐@Oleg的方法,但总有另一种方法:
arr = [[["12:00", 7.0], ["01:00", 3.3], ["02:00", 11.9], ["03:00", 56.5]],
[["12:00", 44.3], ["01:00", 2.25], ["02:00", 2.44], ["03:00", 46.11],
["04:00", 8.9]],
[["01:00", 22.25], ["02:00", 1.84], ["12:00", 13.3]]]
keys = arr.reduce([]) { |keys,a| keys | a.map(&:first) }
arr.map { |a| a.to_h.values_at(*keys) }
.transpose
.map { |e| [keys.shift, e.reduce(0) { |tot,x| tot + x.to_f }] }
#=> [["12:00", 64.6], ["01:00", 27.8], ["02:00", 16.18],
# ["03:00", 102.61], ["04:00", 8.9]]
The steps:
的步骤:
keys = arr.reduce([]) { |keys,a| keys | a.map(&:first) }
#=> ["12:00", "01:00", "02:00", "03:00", "04:00"]
b = arr.map { |a| a.to_h.values_at(*keys) }
#=> [[ 7.0, 3.3, 11.9, 56.5, nil],
# [44.3, 2.25, 2.44, 46.11, 8.9],
# [13.3, 22.25, 1.84, nil, nil]]
c = b.transpose
#=> [[7.0, 44.3, 13.3],
# [3.3, 2.25, 22.25],
# [11.9, 2.44, 1.84],
# [56.5, 46.11, nil],
# [nil, 8.9, nil]]
c.map { |e| [keys.shift, e.reduce(0) { |tot,x| tot + x.to_f }] }
#=> [["12:00", 64.6], ["01:00", 27.8], ["02:00", 16.18],
# ["03:00", 102.61], ["04:00", 8.9]]
Notice that NilClass#to_f converts nil
to 0.0
.
注意,NilClass#to_f将nil转换为0.0。
To elaborate the calculation of b
above:
详细说明上述b的计算:
d = arr.map
#=> #<Enumerator: [[["12:00", 7.0], ["01:00", 3.3], ["02:00", 11.9],
# ["03:00", 56.5]],
# [["12:00", 44.3], ["01:00", 2.25], ["02:00", 2.44],
# ["03:00", 46.11], ["04:00", 8.9]],
# [["01:00", 22.25], ["02:00", 1.84], ["12:00", 13.3]]]:map>
a = d.next
#=> [["12:00", 7.0], ["01:00", 3.3], ["02:00", 11.9], ["03:00", 56.5]]
e = a.to_h
#=> {"12:00"=>7.0, "01:00"=>3.3, "02:00"=>11.9, "03:00"=>56.5}
f = e.values_at(*keys)
#=> e.values_at(*["12:00", "01:00", "02:00", "03:00", "04:00"] )
#=> [7.0, 3.3, 11.9, 56.5, nil]
a = d.next
#=> [["12:00", 44.3], ["01:00", 2.25], ["02:00", 2.44],
# ["03:00", 46.11], ["04:00", 8.9]]
e = a.to_h
#=> {"12:00"=> 44.3, "01:00"=>2.25, "02:00"=>2.44,
# "03:00"=>46.11, "04:00"=> 8.9}
f = e.values_at(*keys)
#=> [44.3, 2.25, 2.44, 46.11, 8.9]
a = d.next
#=> [["01:00", 22.25], ["02:00", 1.84], ["12:00", 13.3]]
e = a.to_h
#=> {"01:00"=>22.25, "02:00"=>1.84, "12:00"=>13.3}
f = e.values_at(*keys)
#=> [13.3, 22.25, 1.84, nil, nil]
c.map
is computed as follows:
c。地图计算如下:
keys = ["12:00", "01:00", "02:00", "03:00", "04:00"]
d = c.map
#=> #<Enumerator: [[ 7.0, 44.3, 13.3], [3.3, 2.25, 22.25],
# [11.9, 2.44, 1.84], [56.5, 46.11, nil],
# [nil, 8.9, nil]]:map>
e = d.next
#=> [7.0, 44.3, 13.3]
f = keys.shift
#=> "12:00"
keys
#=> ["01:00", "02:00", "03:00", "04:00"]
e.reduce(0) { |tot,x| tot + x.to_f }
#=> 64.6
e = d.next
#=> [3.3, 2.25, 22.25]
f = keys.shift
#=> "01:00"
keys
#=> ["02:00", "03:00", "04:00"]
e.reduce(0) { |tot,x| tot + x.to_f }
#=> 27.8
e = d.next
#=> [11.9, 2.44, 1.84]
f = keys.shift
#=> "02:00"
keys
#=> ["03:00", "04:00"]
e.reduce(0) { |tot,x| tot + x.to_f }
#=> 16.18
e = d.next
#=> [56.5, 46.11, nil]
f = keys.shift
#=> "03:00"
keys
#=> ["04:00"]
e.reduce(0) { |tot,x| tot + x.to_f }
#=> 102.61
e = d.next
#=> [nil, 8.9, nil]
f = keys.shift
#=> "04:00"
keys
#=> []
e.reduce(0) { |tot,x| tot + x.to_f }
#=> 8.9
#1
4
You can do it in one line with Hash.merge. Use a block to sum the values during the merge.
你可以在一行中使用hash。merge。在合并期间使用块来求和值。
def sum_arrays(a, b)
Hash[a].merge(Hash[b]){|k, i, j| i + j}.to_a
end
Output:
输出:
a = [["12:00", 7.0], ["01:00", 3.3], ["02:00", 11.9], ["03:00", 56.5]]
b = [["12:00", 44.3], ["01:00", 2.25], ["02:00", 2.44], ["03:00", 46.11], ["04:00", 8.9], ["05:00", 18.187]]
sum_arrays(a,b)
=> [["12:00", 51.3], ["01:00", 5.55], ["02:00", 14.34], ["03:00", 102.61], ["04:00", 8.9], ["05:00", 18.187]]
To sum more than two arrays, add one more line:
若要将两个以上的数组相加,请再加一行:
def sum_many_arrays(*a)
a.reduce{|s, i| sum_arrays(s, i)}
end
Output:
输出:
sum_many_arrays([[:a,1],[:b,2]],[[:a,2],[:b,2],[:c,1]],[[:a,5],[:b,2]])
=> [[:a, 8], [:b, 6], [:c, 1]]
#2
0
I recommend @Oleg's approach, but there's always another way:
我推荐@Oleg的方法,但总有另一种方法:
arr = [[["12:00", 7.0], ["01:00", 3.3], ["02:00", 11.9], ["03:00", 56.5]],
[["12:00", 44.3], ["01:00", 2.25], ["02:00", 2.44], ["03:00", 46.11],
["04:00", 8.9]],
[["01:00", 22.25], ["02:00", 1.84], ["12:00", 13.3]]]
keys = arr.reduce([]) { |keys,a| keys | a.map(&:first) }
arr.map { |a| a.to_h.values_at(*keys) }
.transpose
.map { |e| [keys.shift, e.reduce(0) { |tot,x| tot + x.to_f }] }
#=> [["12:00", 64.6], ["01:00", 27.8], ["02:00", 16.18],
# ["03:00", 102.61], ["04:00", 8.9]]
The steps:
的步骤:
keys = arr.reduce([]) { |keys,a| keys | a.map(&:first) }
#=> ["12:00", "01:00", "02:00", "03:00", "04:00"]
b = arr.map { |a| a.to_h.values_at(*keys) }
#=> [[ 7.0, 3.3, 11.9, 56.5, nil],
# [44.3, 2.25, 2.44, 46.11, 8.9],
# [13.3, 22.25, 1.84, nil, nil]]
c = b.transpose
#=> [[7.0, 44.3, 13.3],
# [3.3, 2.25, 22.25],
# [11.9, 2.44, 1.84],
# [56.5, 46.11, nil],
# [nil, 8.9, nil]]
c.map { |e| [keys.shift, e.reduce(0) { |tot,x| tot + x.to_f }] }
#=> [["12:00", 64.6], ["01:00", 27.8], ["02:00", 16.18],
# ["03:00", 102.61], ["04:00", 8.9]]
Notice that NilClass#to_f converts nil
to 0.0
.
注意,NilClass#to_f将nil转换为0.0。
To elaborate the calculation of b
above:
详细说明上述b的计算:
d = arr.map
#=> #<Enumerator: [[["12:00", 7.0], ["01:00", 3.3], ["02:00", 11.9],
# ["03:00", 56.5]],
# [["12:00", 44.3], ["01:00", 2.25], ["02:00", 2.44],
# ["03:00", 46.11], ["04:00", 8.9]],
# [["01:00", 22.25], ["02:00", 1.84], ["12:00", 13.3]]]:map>
a = d.next
#=> [["12:00", 7.0], ["01:00", 3.3], ["02:00", 11.9], ["03:00", 56.5]]
e = a.to_h
#=> {"12:00"=>7.0, "01:00"=>3.3, "02:00"=>11.9, "03:00"=>56.5}
f = e.values_at(*keys)
#=> e.values_at(*["12:00", "01:00", "02:00", "03:00", "04:00"] )
#=> [7.0, 3.3, 11.9, 56.5, nil]
a = d.next
#=> [["12:00", 44.3], ["01:00", 2.25], ["02:00", 2.44],
# ["03:00", 46.11], ["04:00", 8.9]]
e = a.to_h
#=> {"12:00"=> 44.3, "01:00"=>2.25, "02:00"=>2.44,
# "03:00"=>46.11, "04:00"=> 8.9}
f = e.values_at(*keys)
#=> [44.3, 2.25, 2.44, 46.11, 8.9]
a = d.next
#=> [["01:00", 22.25], ["02:00", 1.84], ["12:00", 13.3]]
e = a.to_h
#=> {"01:00"=>22.25, "02:00"=>1.84, "12:00"=>13.3}
f = e.values_at(*keys)
#=> [13.3, 22.25, 1.84, nil, nil]
c.map
is computed as follows:
c。地图计算如下:
keys = ["12:00", "01:00", "02:00", "03:00", "04:00"]
d = c.map
#=> #<Enumerator: [[ 7.0, 44.3, 13.3], [3.3, 2.25, 22.25],
# [11.9, 2.44, 1.84], [56.5, 46.11, nil],
# [nil, 8.9, nil]]:map>
e = d.next
#=> [7.0, 44.3, 13.3]
f = keys.shift
#=> "12:00"
keys
#=> ["01:00", "02:00", "03:00", "04:00"]
e.reduce(0) { |tot,x| tot + x.to_f }
#=> 64.6
e = d.next
#=> [3.3, 2.25, 22.25]
f = keys.shift
#=> "01:00"
keys
#=> ["02:00", "03:00", "04:00"]
e.reduce(0) { |tot,x| tot + x.to_f }
#=> 27.8
e = d.next
#=> [11.9, 2.44, 1.84]
f = keys.shift
#=> "02:00"
keys
#=> ["03:00", "04:00"]
e.reduce(0) { |tot,x| tot + x.to_f }
#=> 16.18
e = d.next
#=> [56.5, 46.11, nil]
f = keys.shift
#=> "03:00"
keys
#=> ["04:00"]
e.reduce(0) { |tot,x| tot + x.to_f }
#=> 102.61
e = d.next
#=> [nil, 8.9, nil]
f = keys.shift
#=> "04:00"
keys
#=> []
e.reduce(0) { |tot,x| tot + x.to_f }
#=> 8.9