python - 如何基于 1000 个符号字符串打印出带有单个替换元素的 1000 个新字符串？

Question

这里会有一点分子生物学。

所以我需要根据 1000 个核苷酸的主要序列生成 1000 个突变序列。与前面的序列相比，每个随后的突变序列必须有一个随机核苷酸切换到同一类别之一(A 到 G，反之亦然；T 到 C，反之亦然)。此外，必须使用 random.randint 和 random.seed(1)。

这是我目前所拥有的:

import random
# below is the initial sequence
seq = 'CGCCTGTAATCCCAGCACTCTGGGAGGCAGAGGTGGGCCGATCACTTGAGGTCAGGAGTTCGAGACCAGCCTGGGCAACATGGTGAAACACCATCTCTACTAAAAACACAAAAATTAGCCAGGTGTGGTGGCAGGCACCTGCAGTCCCAGCTACTCCGGAGGCTGAGGCAGGAGAATTGCTCGAACCTGGGAGGCAGGGGTTGCAGTGAGCCGACATGGCGCCACTGCACTCCAGTCTGGGCGACAGAGTGAGACCCTATCTCAAAAAAAAAAAAAAAAAAAAAAGACCCAACTCAAGTATCATCTCCAGGAAGCCTTCCCCTACTCCCAGCAATTAAATGCTCCTCAGAGAATTCCCATTTTTGGTTTACTCTTTGGTTTACCTCCAGACAGGAAGCCCCCACTGACACTGTTGTAGTCCCAGGGTGCAACACAAAGCAGAGATCACAAGCTGAGTTTAATAATTGCTTGTGGAATACATGTCCCAAGCCACCTCCTGCAGGAAGCCCTTCCAGATGCCCATTCTAGCCAGTCTGGCTCTTTGCTTCCATACCTTCACAACACTTGTGCCTCCCCCAGGGCCTCTTTCTCATCTTGCTTTCTGGGGCAGCTGTGTGCACATTTGTCTGTGTGCAGCAACTCTCTAAGGCAGGGATTTTTACTCCTATTTTTGATGAGGGGAGCTGTGGCTCAGAGAGGTTGAATAACCTAAGGCCACACAGTGAGTGGCAGAGCCAGGAATGTGACTTGGGTCCATTTGAATCCAAAGTCCCTGTACTTTCCACTGCCCTACCTAGATGTCCCTGTACCTCCTATAAAATCAGCATGGAGCCTGGTGCCTGGTAGTCCCTACAAATATTCACAAATTGGAGCTTAGCTCAGCTCTCAGGCAAGGCCCAGGTCAAAAGGGCAGATACAGCTTTGGGACCTTAGTTGCCACCACATGCCATACCTTCTTCCCAGCAGAAGGACTCCCTCCAAGACAGGGTAGGGGTGGAGG'
n = 0
while n <= 1000: # setting up a cycle for 1000 mutations
    i = random.randint(0, 1001) # choosing  random nucleotide to switch
    if seq[i] == 'A':
        print(seq.replace('A', 'G', 1)) # the third argumunt is supposed to show how many times a nucleotide must be switched but it does't work for some reason
    elif seq[i] == 'G':
        print(seq.replace('G', 'A', 1))
    elif seq[i] == 'C':
        print(seq.replace('C', 'T', 1))
    elif seq[i] == 'T':
        print(seq.replace('T', 'C', 1))
    n = n + 1

我遇到的主要问题是让程序根据先前序列而不是原始序列生成新突变，并且只替换一个核苷酸。

Answer 1

您需要更新循环中的核苷酸序列。字符串不能更改，所以我建议只使用字母列表开始:

import random

# Since string cannot be changed/mutated, 
# break up sequence into a list of strings
seq = list('CGCCTGTAATCCCAGCACTCTGGGAGGCAGAGGTGGGCCGATCACTTGAGGTCAGGAGTTCGAGACCAGCCTGGGCAACATGGTGAAACACCATCTCTACTAAAAACACAAAAATTAGCCAGGTGTGGTGGCAGGCACCTGCAGTCCCAGCTACTCCGGAGGCTGAGGCAGGAGAATTGCTCGAACCTGGGAGGCAGGGGTTGCAGTGAGCCGACATGGCGCCACTGCACTCCAGTCTGGGCGACAGAGTGAGACCCTATCTCAAAAAAAAAAAAAAAAAAAAAAGACCCAACTCAAGTATCATCTCCAGGAAGCCTTCCCCTACTCCCAGCAATTAAATGCTCCTCAGAGAATTCCCATTTTTGGTTTACTCTTTGGTTTACCTCCAGACAGGAAGCCCCCACTGACACTGTTGTAGTCCCAGGGTGCAACACAAAGCAGAGATCACAAGCTGAGTTTAATAATTGCTTGTGGAATACATGTCCCAAGCCACCTCCTGCAGGAAGCCCTTCCAGATGCCCATTCTAGCCAGTCTGGCTCTTTGCTTCCATACCTTCACAACACTTGTGCCTCCCCCAGGGCCTCTTTCTCATCTTGCTTTCTGGGGCAGCTGTGTGCACATTTGTCTGTGTGCAGCAACTCTCTAAGGCAGGGATTTTTACTCCTATTTTTGATGAGGGGAGCTGTGGCTCAGAGAGGTTGAATAACCTAAGGCCACACAGTGAGTGGCAGAGCCAGGAATGTGACTTGGGTCCATTTGAATCCAAAGTCCCTGTACTTTCCACTGCCCTACCTAGATGTCCCTGTACCTCCTATAAAATCAGCATGGAGCCTGGTGCCTGGTAGTCCCTACAAATATTCACAAATTGGAGCTTAGCTCAGCTCTCAGGCAAGGCCCAGGTCAAAAGGGCAGATACAGCTTTGGGACCTTAGTTGCCACCACATGCCATACCTTCTTCCCAGCAGAAGGACTCCCTCCAAGACAGGGTAGGGGTGGAGG')

for n in range(1000):  # setting up a cycle for 1000 mutations
    i = random.randint(0, len(seq)-1)  # choosing  random nucleotide to switch

    print(i)
    print(seq[i])  # i-th nucleotide before the mutation

    if seq[i] == 'A':
        seq[i] = 'G'
    elif seq[i] == 'G':
        seq[i] = 'A'
    elif seq[i] == 'C':
        seq[i] = 'T'
    elif seq[i] == 'T':
        seq[i] = 'C'

    print(seq[i]). # i-th nucleotide after the mutation

    print(''.join(seq))  # join nucleotides into a string for printing