1. 输出原序列的反向互补序列

in1 = open("brca1.fasta", "r")
out1 = open("re_brca1.fasta", "w")

raw = in1.readlines()

序列信息暂时不想改

out1.write(raw[0])
s = raw[1].split("\n")[0]

原序列中存在小写，先统一改为大写

s = s.upper()

不指定替换次数，所以全部替换

s.replace('G', 'C')
s.replace('C', 'G')
s.replace('A', 'T')
s.replace('T', 'A')

逆序输出，再加个换行符：）

out1.write(s[::-1]+"\n")

out1.close()
in1.close()

2. 读取大量数据：试了2millions行的文件,ok

with open('probes.blast.txt') as file:
for line in file: