Question

我有两列

如果列V2是1，那么我想要替换核苷酸互补，如果剩下0就像我写了一个for函数（在我的许多行数据中），但是在他的表现之后我得到了

  V1 V2 V3
  T  1 NA
  A  0 NA
  C  1 G

我使用代码

for(i in nrow(Tri1_a)){

 if(Tri1_a$V2[i] == 1){

  if(Tri1_a$V1[i] == "T")

    Tri1_a$V3[i] = "A"

  if(Tri1_a$V1[i] == "A")

    Tri1_a$V3[i] = "T"

 if(Tri1_a$V1[i] == "G")
    Tri1_a$V3[i] = "C"
 if(Tri1_a$V1[i] == "C")
    Tri1_a$V3[i] = "G"
 }
else{ 

 Tri1_a$V3[i] = Tri1_a$V1[i]
  }

i = i + 1
}

但我想要

  V1 V2 V3
  T  1 A
  A  0 A
  C  1 G

哪里出错？

是否可以在没有for的情况下进行，对于使用申请的考试？

Answer 1

我们可以使用ifelse：

#dummy data
set.seed(1)
genotype <- data.frame(V1=sample(c("A","C","T","G"),size = 10, replace = T ), 
                       V2=sample(c(0,1), size=10, prob = c(0.6, 0.4), replace=T), 
                       stringsAsFactors = F)

genotype$V3 <- ifelse(genotype$V2 == 0, genotype$V1,
                      ifelse(genotype$V1=="A", "T", 
                             ifelse(genotype$V1 == "T", "A",
                                    ifelse(genotype$V1=="C", "G","C"))))

genotype
#    V1 V2 V3
# 1   C  0  C
# 2   C  0  C
# 3   T  1  A
# 4   G  0  G
# 5   A  1  T
# 6   G  0  G
# 7   G  1  C
# 8   T  1  A
# 9   T  0  T
# 10  A  1  T

Answer 2

使用命名向量：

#named vector
comp <- c("A", "T", "C", "G")
names(comp) <- c("T", "A", "G", "C")

#map with names when V2 is 1
genotype$V3 <- ifelse(genotype$V2 == 1, comp[genotype$V1], genotype$V1)

补体基因型与条件

2 个答案: