如何使函数的输出为列表类型而不是NoneType

Question

我正在运行的函数是以下

def ambiguous_to_unambiguous(seq):
ambig = {'R': ['A', 'G'], 'V':['A', 'C', 'G'], 'W':['A', 'T'], 'S':['C', 'G'], 'Y':['C', 'T'], 'K':['G', 'T'], 'V':['A', 'C', 'G'], 'H':['A', 'C', 'T'],
        'D':['A', 'G', 'T'], 'B':['C', 'G', 'T'], 'N':['G', 'A', 'T', 'C']} #from IU pack
groups = itertools.groupby(seq, lambda char:char not in ambig)
splits = []
for b,group in groups:
    if b:
        splits.extend([[g] for g in group])
    else:
        for nuc in group:
            splits.append(ambig[nuc])
possible_seqs = [''.join(p) for p in itertools.product(*splits)]
print(possible_seqs) 

我需要这个ambique_to_unambique((函数的输出是可迭代的。这在当前是不可能的，因为输出是NoneType。这是我想在中使用ambique_to_unambique((函数的代码块

def seq_ID_and_weight(file_name):
with open (file_name) as file:
    ID_weight = {} #create an empty dictionary
    for seq in file:
        weight_min = [10000]
        weight_max = [0]
        if ambiguous_to_unambiguous(seq) != seq:
            possible_sequences = ambiguous_to_unambiguous(seq)
            for possib in possible_sequences:
                if possib.molecular_weight < weight_min: weight_min = possib.molecular_weight
                elif possib.molecular_weight > weight_max: weight_max = possib.molecular_weight
            ID_weight.append({seq.id: [weight_min, weight_max]})
        else:
            ID_weight.append({seq.id: seq.molecular_weight})
    print(ID_weight)

但这给了我以下错误：

    ---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-19-588e4dcc12bb> in <module>
----> 1 seq_ID_and_weight('short.fasta')
<ipython-input-18-ad41a9ecd674> in seq_ID_and_weight(file_name)
      7             if ambiguous_to_unambiguous(seq) != seq:
      8                 possible_sequences = ambiguous_to_unambiguous(seq)
----> 9                 for possib in possible_sequences:
     10                     if possib.molecular_weight < weight_min: weight_min = possib.molecular_weight
     11                     elif possib.molecular_weight > weight_max: weight_max = possib.molecular_weight
TypeError: 'NoneType' object is not iterable

我用错这个函数了吗？我尝试过map((函数和使用*运算符打印，但键入的内容保持不变。

Answer 1

当函数没有return语句时，它"返回"；没有一个