自定义列表到字典列表

Question

I have list of lists and I wish to create a dictionary with length of each element as values. I tried the following:

tmp = [['A', 'B', 'E'], ['B', 'E', 'F'], ['A', 'G']]
tab = []
for line in tmp:
    tab.append(dict((k, len(tmp)) for k in line))

But it gives the output as:

[{'A': 3, 'B': 3, 'E': 3}, {'B': 3, 'E': 3, 'F': 3}, {'A': 3, 'G': 3}]

What is the modification that I should make to get the output:

{['A', 'B', 'E']:3, ['B', 'E', 'F']:3, ['A', 'G']:2}

Thanks in advance.

AP

Answer 1

You can't use list objects as dictionary keys, they are mutable and unhashable. You can convert them to tuple. Also note that you are looping over each sub list. You can use a generator expression by only looping over the main list:

In [3]: dict((tuple(sub), len(sub)) for sub in tmp)
Out[3]: {('A', 'B', 'E'): 3, ('A', 'G'): 2, ('B', 'E', 'F'): 3}

Answer 2

{tuple(t):len(t) for t in tmp}

Input :

[['A', 'B', 'E'], ['B', 'E', 'F'], ['A', 'G']]

Output :

{('A', 'G'): 2, ('A', 'B', 'E'): 3, ('B', 'E', 'F'): 3}

Dictionnary does not accept list as key, but tuple