python - 折叠列表列表，按特定元素分组并附加其他元素

Question

我怎样才能转换一个列表，例如:

l=[ ['A', 'C21'], ['A','D43'],['B','D34'],['C','D45'],['C',D56']

到:

[ ['A','C21 D43'], ['B','D34'],['C','D45 D56'] ]

其中根据每个子列表的#0元素进行分组 和元素 #1 是在每个组内连接的字符串？

Answer 1

试试这个:

l=[ ['A', 'C21'], ['A','D43'],['B','D34'],['C','D45'],['C','D56']]
x = {}

for a in l:
    if a[0] not in x.keys():
        x[a[0]] = [a[1]]
    else:
        x[a[0]].append(a[1])

print x

array_result = []
for keys, vals in x.iteritems():
    array_result.append([keys, ' '.join(vals)])

print array_result