Question

我想知道下面的代码可能出现什么问题，以及为什么我收到错误KeyError：＆＃39; [＆＃39; ？

该程序旨在将输入的DNA序列翻译成RNA序列，然后从RNA []中存储的RNA序列翻译产生来自dict的AMINO ACID序列。

由于

DNA = "ACAAGATGCCATTGTCCCCCGGCCTCCTGCTGCTGCTGCTCTCCGGGGCCACGGCCACCGCTGCCCTGC"
RNA = []

AMINO_ACIDS = {"UUU":"F", "UUC":"F", "UUA":"L", "UUG":"L",
    "UCU":"S", "UCC":"s", "UCA":"S", "UCG":"S",
    "UAU":"Y", "UAC":"Y", "UAA":"STOP", "UAG":"STOP",
    "UGU":"C", "UGC":"C", "UGA":"STOP", "UGG":"W",
    "CUU":"L", "CUC":"L", "CUA":"L", "CUG":"L",
    "CCU":"P", "CCC":"P", "CCA":"P", "CCG":"P",
    "CAU":"H", "CAC":"H", "CAA":"Q", "CAG":"Q",
    "CGU":"R", "CGC":"R", "CGA":"R", "CGG":"R",
    "AUU":"I", "AUC":"I", "AUA":"I", "AUG":"M",
    "ACU":"T", "ACC":"T", "ACA":"T", "ACG":"T",
    "AAU":"N", "AAC":"N", "AAA":"K", "AAG":"K",
    "AGU":"S", "AGC":"S", "AGA":"R", "AGG":"R",
    "GUU":"V", "GUC":"V", "GUA":"V", "GUG":"V",
    "GCU":"A", "GCC":"A", "GCA":"A", "GCG":"A",
    "GAU":"D", "GAC":"D", "GAA":"E", "GAG":"E",
    "GGU":"G", "GGC":"G", "GGA":"G", "GGG":"G",}

RNA_2 = str(RNA)
for char in DNA:
    if char == "G":
        RNA.append("C")
    elif char == "C":
        RNA.append("G")
    elif char == "A":
        RNA.append("U")
    elif char == "T":
        RNA.append("A")

translated = ''.join(AMINO_ACIDS[i] for i in RNA_2)

print("DNA sequence: " + DNA)
print()
print("Length of DNA sequence in base pairs: " + str(len(DNA)))
print()
print("RNA sequence of DNA sequence: " +("".join(RNA)))
print()
print("AMINO ACID sequence: " + str(translated))

Answer 1

您不需要RNA_2，但您确实需要一种方法将RNA字符串拆分为三个字符串的块。借用this post中的块函数：

def chunks(l, n):
    """ Yield successive n-sized chunks from l.
    """
    for i in xrange(0, len(l), n):
        yield l[i:i+n]

DNA = "ACAAGATGCCATTGTCCCCCGGCCTCCTGCTGCTGCTGCTCTCCGGGGCCACGGCCACCGCTGCCCTGC"
RNA = []

AMINO_ACIDS = {"UUU":"F", "UUC":"F", "UUA":"L", "UUG":"L",
    "UCU":"S", "UCC":"s", "UCA":"S", "UCG":"S",
    "UAU":"Y", "UAC":"Y", "UAA":"STOP", "UAG":"STOP",
    "UGU":"C", "UGC":"C", "UGA":"STOP", "UGG":"W",
    "CUU":"L", "CUC":"L", "CUA":"L", "CUG":"L",
    "CCU":"P", "CCC":"P", "CCA":"P", "CCG":"P",
    "CAU":"H", "CAC":"H", "CAA":"Q", "CAG":"Q",
    "CGU":"R", "CGC":"R", "CGA":"R", "CGG":"R",
    "AUU":"I", "AUC":"I", "AUA":"I", "AUG":"M",
    "ACU":"T", "ACC":"T", "ACA":"T", "ACG":"T",
    "AAU":"N", "AAC":"N", "AAA":"K", "AAG":"K",
    "AGU":"S", "AGC":"S", "AGA":"R", "AGG":"R",
    "GUU":"V", "GUC":"V", "GUA":"V", "GUG":"V",
    "GCU":"A", "GCC":"A", "GCA":"A", "GCG":"A",
    "GAU":"D", "GAC":"D", "GAA":"E", "GAG":"E",
    "GGU":"G", "GGC":"G", "GGA":"G", "GGG":"G",}

for char in DNA:
    if char == "G":
        RNA.append("C")
    elif char == "C":
        RNA.append("G")
    elif char == "A":
        RNA.append("U")
    elif char == "T":
        RNA.append("A")


translated = ''.join(AMINO_ACIDS[i] for i in chunks("".join(RNA), 3))

print("DNA sequence: " + DNA)
print()
print("Length of DNA sequence in base pairs: " + str(len(DNA)))
print()
print("RNA sequence of DNA sequence: " +("".join(RNA)))
print()
print("AMINO ACID sequence: " + str(translated))

结果：

DNA sequence: ACAAGATGCCATTGTCCCCCGGCCTCCTGCTGCTGCTGCTCTCCGGGGCCACGGCCACCGCTGCCCTGC
()
Length of DNA sequence in base pairs: 69
()
RNA sequence of DNA sequence: UGUUCUACGGUAACAGGGGGCCGGAGGACGACGACGACGAGAGGCCCCGGUGCCGGUGGCGACGGGACG
()
AMINO ACID sequence: CSTVTGGRRTTTTRGPGAGGDGT

关于原始错误的更多信息。我想你可能会误解RNA_2 = str(RNA)的作用。它并不意味着“现在和将来，RNA_2将成为RNA的字符串版本，并且每当RNA发生变化时都会保持最新状态”。这意味着“及时将RNA的内容转化为一串，这就是RNA_2的含义，即使RNA后来发生变化”。因此，即使您已将值附加到RNA，RNA_2也将为“[]”。这是KeyError的来源。 “[”是RNA_2的第一个字符，而AMINO_ACIDS中不存在“[”。

但即使您在之后完成了追加循环后RNA_2 = str(RNA) ，我也认为它不会为您提供您想要的结果。它将是['U', 'G', 'U', 'U', 'C', ...而不是"UGUUC"。如果你想要后者，你应该使用"".join(RNA)而不是str(RNA)。

但是，即使您使用"".join(RNA)，迭代它并尝试访问AMINO_ACIDS也行不通，因为AMINO_ACID的键长度都是三个字符，并且迭代string一次给你一个字符。这就是chunk的用武之地，让你一次迭代三个字符。

DICT功能不适用于RNA翻译程序

1 个答案: