Question

我刚刚开始学习python编程。在课堂上，我们被要求生成一个随机的DNA序列，该序列不包含特定的6个字母的序列（AACGTT）。关键是要创建一个始终返回合法序列的函数。目前，我的函数大约有78％的时间生成正确的序列。我如何使其在100％的时间内返回合法的合法地位？任何帮助表示赞赏。

这是我的代码现在的样子：

from random import choice
def generate_seq(length, enzyme):
    list_dna = []
    nucleotides = ["A", "C", "T", "G"]
    i = 0
    while i < 1000:
        nucleotide = choice(nucleotides)
        list_dna.append(nucleotide)
        i = i + 1

    dna = ''.join(str(nucleotide) for nucleotide in list_dna)
    return(dna) 


seq = generate_seq(1000, "AACGTT")
if len(seq) == 1000 and seq.count("AACGTT") == 0:
    print(seq)

Answer 1

一种选择是检查循环中的最后几个条目，并且仅在未创建“不良”序列时才继续追加。但是，此可能导致具有“ AACGT”序列的机会比真正随机的机会高，只是使用不同的字母而不是最后一个“ T”

from random import choice
def generate_seq(length, enzyme):
    list_dna = []
    nucleotides = ["A", "C", "T", "G"]
    i = 0
    while i < 1000:
        nucleotide = choice(nucleotides)
        list_dna.append(nucleotide)
        #check for invalid sequence. If found, remove last element and redraw
        if ''.join(list_dna[-6:]) == "AACGTT":
            list_dna.pop()
        else:
            i = i + 1

    dna = ''.join(str(nucleotide) for nucleotide in list_dna)
    return(dna) 


seq = generate_seq(1000, "AACGTT")
if len(seq) == 1000 and seq.count("AACGTT") == 0:
    print(seq)

Answer 2

一个想法是检查前5个核苷酸是否等于AACGT，在这种情况下，只能从["A", "C", "G"]中选择。

from random import choice


def generate_seq(length, enzyme, bad_prefix="AACGT"):
    list_dna = []
    nucleotides = ["A", "C", "T", "G"]
    i = 0
    while i < 1000:
        if list_dna[-5:] != bad_prefix:
            nucleotide = choice(nucleotides)
        else:
            nucleotide = choice(["A", "C", "G"])
        list_dna.append(nucleotide)
        i = i + 1

    dna = ''.join(str(nucleotide) for nucleotide in list_dna)
    return dna


seq = generate_seq(1000, "AACGTT")
if len(seq) == 1000 and seq.count("AACGTT") == 0:
    print(seq)

生成不包含特定序列的DNA序列

2 个答案: