使用函数制作 dict 不起作用，但在函数之外可以

Question

我有一个我似乎无法找到并解决的问题。

FASTA = >header1
         ATCGATCGATCCCGATCGACATCAGCATCGACTAC
         ATCGACTCAAGCATCAGCTACGACTCGACTGACTACGACTCGCT
        >header2
         ATCGATCGCATCGACTACGACTACGACTACGCTTCGTATCAGCATCAGCT
         ATCAGCATCGACGACGACTAGCACTACGACTACGACGATCCCGATCGATCAGCT

def dnaSequence():
    '''
    This function makes a dict called DNAseq by reading the fasta file 
    given as first argument on the command line
    INPUT: Fasta file containing strings
    OUTPUT: key is header and value is sequence
    '''

    DNAseq = {}
    for line in FASTA:
        line = line.strip()
        if line.startswith('>'):
            header = line
            DNAseq[header] = ""
        else:
            seq = line
            DNAseq[header] = seq

    return DNAseq



def digestFragmentsWithOneEnzyme(dnaSequence):
    '''
    This function digests the sequence from DNAseq into smaller parts
    by using the enzymes listed in the MODES.
    INPUT: DNAseq and the enzymes from sys.argv[2:]
    OUTPUT: The DNAseq is updated with the segments gained from the
    digesting
    '''
    enzymes = sys.argv[2:]

    updated_list = []
    for enzyme in enzymes:
        pattern = MODES(enzyme)
        p = re.compile(pattern)
        for dna in DNAseq.keys():
            matchlist = re.findall(p,dna)
            updated_list = re.split(MODES, DNAseq)
            DNAseq.update((key, updated_list.index(k)) for key in
            d.iterkeys())
    return DNAseq


def getMolecularWeight(dnaSequence):
    '''
    This function calculates the molWeight of the sequence in DNAseq
    INPUT: the updated DNAseq from the previous function as a dict
    OUTPUT: The DNAseq is updated with the molweight of the digested fragments
    '''

    results = []
    for seq in DNAseq.keys():
        results = sum((dnaMass[base]) for base in DNAseq[seq])
        DNAseq.update((key, results.index(k)) for key in
        d.iterkeys())
    return DNAseq


def main(argv=None):
    '''
    This function prints the results of the digested DNA sequence on in the terminal.
    INPUT: The DNAseq from the previous function as a dict
    OUTPUT: name     weight weight weight
            name2    weight weight weight
    '''
    if argv == None:
        argv = sys.argv
    if len(argv) <2:
        usage()
        return 1

    digestFragmentsWithOneEnzyme(dnaSequence())
    Genes = getMolecularWeight(digestFragmentsWithOneEnzyme())
    print ({header},{seq}).format(**DNAseq)
    return 0



if __name__ == '__main__':
    sys.exit(main())

在第一个函数中，我试图从 fasta 文件中创建一个 dict，在第二个函数中使用相同的 dict，其中序列被正则表达式切片，最后计算 molweight。

我的问题是，由于某种原因，Python 无法识别我的dict，并且出现错误：

名称错误 DNAseq 未定义

如果我在函数之外创建dict，那么我确实拥有dict。

Answer 1

您将字典作为dnaSequence 传递给这两个函数，而不是DNAseq。

请注意，这是一种非常奇怪的函数调用方式。当您将序列传递给它时，您完全忽略了第一次调用 digestFragmentsWithOneEnzyme 的结果，然后尝试再次调用它以将结果传递给 getMolecularWeight 但您实际上未能在该调用中传递序列，所以这会如果你走到那一步，实际上是错误的。

我认为你想要做的是：

sequence = dnaSequence()
fragments = digestFragmentsWithOneEnzyme(sequence)
genes = getMolecularWeight(fragments)

并且您应该避免将参数调用为具有相同名称的两个函数作为单独的函数，因为这将隐藏函数名称。相反，请选择一个新名称：

def digestFragmentsWithOneEnzyme(sequence):
    ...
    for dna in sequence:

（您无需调用 keys() - 遍历 dict 总是在键上。）