python - 合并二维数组

Question

假设我有两个数组:

arrayOne = [["james", 35], ["michael", 28], ["steven", 23], 
            ["jack", 18], ["robert", 12]]
arrayTwo = [["charles", 45], ["james",  36], ["trevor", 24], 
            ["michael", 17], ["steven", 4]]

我想合并它们，这样我就有了一个二维数组，其中每个内部数组的第一个元素是名字(james、charles 等)。内部数组的第二个元素是它在 arrayOne 中的相应值，如果没有相应的值则为 0。第三个元素则相反。只要数字与名称匹配，顺序并不重要。换句话说，我会得到这样的东西

arrayResult = [["james", 35, 36], ["michael", 28, 17], ["steven", 23, 4],
               ["jack", 18, 0], ["robert", 12, 0], ["charles", 0, 45],
               ["trevor", 0, 4]]

此外，我正在尝试拥有它，以便在我要提供另一个数组时可以向该数组结果添加更多“列”。

Answer 1

看起来您真正需要的是字典，而不是数组。如果你使用字典，这个问题就会变得容易得多。转换为字典再简单不过了:

dictOne = dict(arrayOne)
dictTwo = dict(arrayTwo)

从那里，你可以像这样把它们放在一起:

combined = dict()
for name in set(dictOne.keys() + dictTwo.keys()):
  combined[name] = [ dictOne.get(name, 0), dictTwo.get(name, 0) ]

这样做是创建一个名为 combined 的新字典，我们将把最终数据放入其中。然后，我们从两个原始字典中创建一组键。使用集合可确保我们不会做任何事情两次。最后，我们遍历这组键并将每对值添加到 combined 字典，告诉调用 .get 方法以提供 0 如果没有值。如果您需要将组合字典切换回数组，那也很容易:

arrayResult = []
for name in combined:
  arrayResult.append([ name ] + combined[name])

假设你想在结果字典中添加另一列，你所要做的就是将中间代码更改为如下所示:

combined = dict()
for name in set(dictOne.keys() + dictTwo.keys() + dictThree.keys()):
  combined[name] = [ dictOne.get(name, 0), dictTwo.get(name, 0), dictThree.get(name, 0) ]

如果您想将所有这些逻辑封装在一个函数中(这是我推荐的做法)，您可以这样做:

def combine(*args):
  # Create a list of dictionaries from the arrays we passed in, since we are
  # going to use dictionaries to solve the problem.
  dicts = [ dict(a) for a in args ]

  # Create a list of names by looping through all dictionaries, and through all
  # the names in each dictionary, adding to a master list of names
  names = []
  for d in dicts:
    for name in d.keys():
      names.append(name)

  # Remove duplicates in our list of names by making it a set
  names = set(names)

  # Create a result dict to store results in
  result = dict()

  # Loop through all the names, and add a row for each name, pulling data from
  # each dict we created in the beginning
  for name in names:
    result[name] = [ d.get(name, 0) for d in dicts ]

  # Return, secure in the knowledge of a job well done. :-)
  return result

# Use the function:
resultDict = combine(arrayOne, arrayTwo, arrayThree)