从Python中的字典列表中获取值列表

Question

I created a dictionary in the following format with keys and a list of attributes associated with each key:

inputDatasets = {
    "data1": ["Path to data 1", "Attribute1", "Attribute2", "Attribute3"],
    "data2": ["Path to data 2", "Attribute1", "Attribute2", "Attribute3"],
}

I would like to get a list of all the "Attribute2" contained in the dictionary. For now I use:

attr2 = []
for a, b in inputDatasets.items():
    attr2.append(b[2])

But is there a more elegant way to do that?

Answer 1

You could use a list comprehension, looping only through the values instead of key-value pairs:

attr2 = [b[2] for b in inputDatasets.values()]

Alternatively, but not as elegantly, a map with a lambda could be useful:

attr2 = list(map(lambda b:b[2], inputDatasets.values()))

Answer 2

你也可以这样做

attr2 = [v[2] for v in inputDatasets.values()]