如何在数据帧中更改字符

Question

我想将第3-9栏中的"U“改为"N”，并将"H“改为同一行的”类型“。例如，第一行中的"H“将改为"M"，依此类推。我真的很感激对R脚本的任何帮助。谢谢。XW

ID        type       A01      A02      A03      A04      A05       A06      A07
ss001        M        C        A        U        A        A        H        A
ss002        R        A        H        A        A        A        G        A
ss003        R        H        A        G        A        A        A        U
ss004        R        A        U        A        A        A        A        A
ss005        Y        C        C        H        T        T        C        C
ss006        Y        C        T        U        C        C        C        H
ss007        R        A        G        A        H        G        U        G
ss008        K        G        U        T        G        T        H        G
ss009        Y        T        H        C        T        T        U        C
ss010        K        T        G        T        H        G        T        T

Answer 1

这应该是一种非常有效的方法：

M <- as.matrix(df[-c(1, 2)])        ## Faster to work on a matrix
M[M == "U"] <- "N"                  ## Replace "U" with "N"
H <- which(M == "H", arr.ind=TRUE)  ## Identify the Hs
M[H] <- df[cbind(H[, "row"], 2)]    ## Replace with values from "type"
cbind(df[1:2], M)                   ## Combine
#       ID type A01 A02 A03 A04 A05 A06 A07
# 1  ss001    M   C   A   N   A   A   M   A
# 2  ss002    R   A   R   A   A   A   G   A
# 3  ss003    R   R   A   G   A   A   A   N
# 4  ss004    R   A   N   A   A   A   A   A
# 5  ss005    Y   C   C   Y   T   T   C   C
# 6  ss006    Y   C   T   N   C   C   C   Y
# 7  ss007    R   A   G   A   R   G   N   G
# 8  ss008    K   G   N   T   G   T   K   G
# 9  ss009    Y   T   Y   C   T   T   N   C
# 10 ss010    K   T   G   T   K   G   T   T

Answer 2

您可以通过调用数据行上的apply来完成此操作：

# Read in data frame with data stored as characters
df = read.table(text="ID        type       A01      A02      A03      A04      A05       A06      A07
ss001        M        C        A        U        A        A        H        A
ss002        R        A        H        A        A        A        G        A
ss003        R        H        A        G        A        A        A        U
ss004        R        A        U        A        A        A        A        A
ss005        Y        C        C        H        T        T        C        C
ss006        Y        C        T        U        C        C        C        H
ss007        R        A        G        A        H        G        U        G
ss008        K        G        U        T        G        T        H        G
ss009        Y        T        H        C        T        T        U        C
ss010        K        T        G        T        H        G        T        T", header=T, stringsAsFactors=F)

# Manipulate rows
df.mod = as.data.frame(t(apply(df, 1, function(x) {
    to.modify <- x[c(-1, -2)]
    to.modify[to.modify == "U"] <- "N"
    to.modify[to.modify == "H"] <- x[2]
    return(c(x[1:2], to.modify))
})))
names(df.mod) <- names(df)
df.mod
#       ID type A01 A02 A03 A04 A05 A06 A07
# 1  ss001    M   C   A   N   A   A   M   A
# 2  ss002    R   A   R   A   A   A   G   A
# 3  ss003    R   R   A   G   A   A   A   N
# 4  ss004    R   A   N   A   A   A   A   A
# 5  ss005    Y   C   C   Y   T   T   C   C
# 6  ss006    Y   C   T   N   C   C   C   Y
# 7  ss007    R   A   G   A   R   G   N   G
# 8  ss008    K   G   N   T   G   T   K   G
# 9  ss009    Y   T   Y   C   T   T   N   C
# 10 ss010    K   T   G   T   K   G   T   T