r - 补充 DNA 序列

Question

假设我有一个 DNA 序列。我想得到它的补充。我使用了以下代码，但我没有得到它。我究竟做错了什么 ？

s=readline()
ATCTCGGCGCGCATCGCGTACGCTACTAGC
p=unlist(strsplit(s,""))
h=rep("N",nchar(s))
unlist(lapply(p,function(d){
for b in (1:nchar(s)) {    
    if (p[b]=="A") h[b]="T"
    if (p[b]=="T") h[b]="A"
    if (p[b]=="G") h[b]="C"
    if (p[b]=="C") h[b]="G"
}

Answer 1

使用 chartr为此目的而构建的:

> s
[1] "ATCTCGGCGCGCATCGCGTACGCTACTAGC"
> chartr("ATGC","TACG",s)
[1] "TAGAGCCGCGCGTAGCGCATGCGATGATCG"

只需给它两个等长的字符串和你的字符串。还对翻译参数进行了矢量化:

> chartr("ATGC","TACG",c("AAAACG","TTTTT"))
[1] "TTTTGC" "AAAAA" 

注意我正在替换 DNA 的字符串表示而不是向量。要转换向量，我将创建一个查找图作为命名向量和索引:

> p
 [1] "A" "T" "C" "T" "C" "G" "G" "C" "G" "C" "G" "C" "A" "T" "C" "G" "C" "G" "T"
[20] "A" "C" "G" "C" "T" "A" "C" "T" "A" "G" "C"
> map=c("A"="T", "T"="A","G"="C","C"="G")
> unname(map[p])
 [1] "T" "A" "G" "A" "G" "C" "C" "G" "C" "G" "C" "G" "T" "A" "G" "C" "G" "C" "A"
[20] "T" "G" "C" "G" "A" "T" "G" "A" "T" "C" "G"