在R中第一次和最后一次的字符值时找到列索引？

Question

我有一个看起来像这样的数据框

1

我想找到第一次和最后一次a时每行的列索引 例如：对于行2,10，它是void array_init(void) { arr_1[0] = add1; arr_1[1] = sub1; }

Answer 1

你可以这样做：

x <- df==1
rbind(max.col(x, "first"), max.col(x, "last"))

#     [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
#[1,]    2    1    1    1    2    3    3    2    2     4
#[2,]    2    6    6    4    4    5    6    6    2     6

或apply：

apply(df, 1, function(x) c(min(which(x==1)),max(which(x==1))))

数据

df <- structure(list(a = c(0, 1, 1, 1, 0, 0, 0, 0, 0, 0), b = c(1, 
0, 0, 0, 1, 0, 0, 1, 1, 0), c = c(0, 1, 0, 1, 0, 1, 1, 1, 0, 
0), d = c(0, 1, 0, 1, 1, 0, 1, 0, 0, 1), e = c(0, 0, 0, 0, 0, 
1, 0, 1, 0, 1), f = c(0, 1, 1, 0, 0, 0, 1, 1, 0, 1)), .Names = c("a", 
"b", "c", "d", "e", "f"), row.names = c(NA, -10L), class = "data.frame")