Question

我想在R中的每一行中选择最后2个值（忽略NA）并将最后2个值放在新的data.frame

中

这是一个可重复的例子

       V10 V11 V12 V13 V14 V15
1      116 174  NA  NA  NA  NA
2       NA  NA  NA  NA  NA  NA
3       NA  NA  NA  NA  NA  NA
4       NA  NA  NA  NA  NA  NA
5       NA  NA  NA  NA  NA  NA
6       NA  NA  NA  NA  NA  NA
7       NA  NA  NA  NA  NA  NA
957594 115 116 120 613 127 127
957595  NA  NA  NA  NA  NA  NA
957596  NA  NA  NA  NA  NA  NA

 tss2 <- structure(list(V10 = c(116L, NA, NA, NA, NA, NA, NA, 115L, NA,NA),
    V11 = c(174L, NA, NA, NA, NA, NA, NA, 116L, NA, NA),
    V12 = c(NA,NA, NA, NA, NA, NA, NA, 120L, NA, NA),
    V13 = c(NA, NA, NA, NA,NA, NA, NA, 613L, NA, NA),
    V14 = c(NA, NA, NA, NA, NA, NA, NA,127L, NA, NA),
    V15 = c(NA, NA, NA, NA, NA, NA, NA, 127L,
    NA,NA)), .Names = c("V10", "V11", "V12", "V13",
    "V14", "V15"), class = "data.frame", row.names
    = c(1L,2L, 3L, 4L, 5L, 6L, 7L, 957594L, 957595L, 957596L))

预期结果为

Pos1 | Pos2 
116  | 174
127  | 127

Answer 1

转换为矩阵可能会加快速度：

ma = apply(as.matrix(tss2), MARGIN = 1, FUN = function(x) tail(na.omit(x), 2))

# risky version: should work *if* there aren't rows with exactly one non-missing element
matrix(unlist((ma)), ncol = 2, byrow = T)
#      [,1] [,2]
# [1,]  116  174
# [2,]  127  127

# safe version
matrix(unlist((ma[sapply(ma, function(x) length(x) == 2)])), ncol = 2, byrow = T)

Answer 2

您可以使用以下循环：

new_data <- list()
for(i in 1:nrow(tss2)) {
  new_data[[i]] <- tail(as.numeric(tss2[i, ][complete.cases(as.numeric(tss2[i, ]))]), 2)
}
new_data <- new_data[lapply(new_data, length) == 2]
new_data <- t(matrix(unlist(new_data), ncol = 2))

选择R中每行的最后2个值

2 个答案: