假設我有一個這樣的陣列：
arr=[["1"], ["1"], ["2", "2"], ["2.1", "0.8"], ["2.2", "0.2"],
["1"], ["2", "3"], ["2", "0.8"], ["2", "0.4"], ["1"], ["2"],
["1", "0.8"], ["2", "0.4"], ["3", "0.3"]]
即，一系列長度為 1 的子串列（1 個或更多）后跟一系列長度大于 1 的子串列（1 個或更多）。
我想將該串列分為：
[[["1"], ["1"], ["2", "2"], ["2.1", "0.8"], ["2.2", "0.2"]],
[["1"], ["2", "3"], ["2", "0.8"], ["2", "0.4"]],
[["1"], ["2"], ["1", "0.8"], ["2", "0.4"], ["3", "0.3"]]]
即，長度為 1 的子串列與以下長度大于 1 的子串列組合成這些子串列的單個子串列。
這有效：
data = []
while arr.length > 0
tmp = []
while arr.length > 0 && arr[0].length() == 1
tmp << arr.shift
end
while arr.length > 0 && arr[0].length() > 1
tmp << arr.shift
end
data << tmp
end
p data
# [[["1"], ["1"], ["2", "2"], ["2.1", "0.8"], ["2.2", "0.2"]], [["1"], ["2", "3"], ["2", "0.8"], ["2", "0.4"]], [["1"], ["2"], ["1", "0.8"], ["2", "0.4"], ["3", "0.3"]]]
但這似乎超級笨拙。是否有一個.groupby或觸發器或某種形式的 Ruby 列舉器我想更容易地做到這一點？
uj5u.com熱心網友回復：
作為對@dawg 答案的改進，如果我們傳遞給的塊:slice_when檢查長度b是否大于長度a：
data = arr.slice_when { |a, b| b.length < a.length }.to_a
結果是：
[[["1"], ["1"], ["2", "2"], ["2.1", "0.8"], ["2.2", "0.2"]],
[["1"], ["2", "3"], ["2", "0.8"], ["2", "0.4"]],
[["1"], ["2"], ["1", "0.8"], ["2", "0.4"], ["3", "0.3"]]]
這只正確處理陣列具有長度1或2. 為了使它更健壯，我們可以檢查我們是否只在b有 length時才這樣做1。
data = arr.slice_when { |a, b| b.length == 1 && b.length < a.length }.to_a
現在，如果：
arr = [["1"], ["1"], ["2", "2"], ["2.1", "0.8"], ["2.2", "0.2"], ["1", "3", "4"], ["1", "1"],
["1"], ["2", "3"], ["2", "0.8"], ["2", "0.4"], ["1"], ["2"],
["1", "0.8"], ["2", "0.4"], ["3", "0.3"]]
結果是：
[[["1"], ["1"], ["2", "2"], ["2.1", "0.8"], ["2.2", "0.2"], ["1", "3", "4"], ["1", "1"]],
[["1"], ["2", "3"], ["2", "0.8"], ["2", "0.4"]],
[["1"], ["2"], ["1", "0.8"], ["2", "0.4"], ["3", "0.3"]]]
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