python 中获取反向序列及互补序列

>>> myseq = 'AGCTGGCTA'
>>> myseq[::-1]                                          ## 利用切片实现 'ATCGGTCGA'
>>> temp = []
>>> for i in reversed(myseq):                            ## 借助reversed函数实现
...     temp.append(i)
...
>>> temp
['A', 'T', 'C', 'G', 'G', 'T', 'C', 'G', 'A']
>>> "".join(temp)             
'ATCGGTCGA'

>>> myseq = 'AGCTGGCTA'                                  ## 测试字符串
>>> myseq = myseq.replace("A", "t")                      ## 防止碱基混淆，先转换为互补碱基的小写字母 >>> myseq = myseq.replace("T", "a")
>>> myseq = myseq.replace("C", "g")
>>> myseq = myseq.replace("G", "c")
>>> myseq
'tcgaccgat'
>>> myseq = myseq.upper()                                ## 整个字符串转换为大小 >>> myseq
'TCGACCGAT'

>>> myseq = 'AGCTGGCTA'
>>> str1 = ""
>>> for i in myseq:                                     ## 利用循环获取互补序列
...     if i == "A":
...             str1 += "T"
...     if i == "T":
...             str1 += "A"
...     if i == "C":
...             str1 += "G"
...     if i == "G":
...             str1 += "C"
...
>>> str1         
'TCGACCGAT'
>>> str1[::-1]                                         ## 获取反向序列 'TAGCCAGCT'

>>> myseq = 'AGCTGGCTA'
>>> dict1 = {"A":"T", "T":"A", "C":"G", "G":"C"}     ## 匹配模板 >>> [dict1[k] for k in myseq]                        ## 利用列表内循环结构获取互补序列
['T', 'C', 'G', 'A', 'C', 'C', 'G', 'A', 'T']
>>> [dict1[k] for k in myseq][::-1]
['T', 'A', 'G', 'C', 'C', 'A', 'G', 'C', 'T']
>>> "".join([dict1[k] for k in myseq][::-1])         ## 取反并转换为字符串 'TAGCCAGCT'