Question

我有一个数据框，其一部分如下所示：

library(data.table)
df <- fread(
"round1 round2  round3  round4  round5  round6 a
8   12  18  32  40  36  32
6   12  18  24  30  36  30
8   16  18  24  30  36  18
4   12  12  24  30  36  24
6   16  24  32  40  48  24
8   12  18  24  30  36  30
8   12  18  24  30  36  18
8   16  24  32  40  48  40
8   16  24  24  30  48  48",
  header = TRUE
)

我想创建一个名为x的列，该列将简单地选择等于a中条目的整数。我尝试遵循，但是语法不正确。

for (i in df$a){ 
    if (df$a[i] = df$round2[i]){
        df$x[i] = 1
    } ifelse (df$a[i] = df$round3[i]){
        df$x[i] = 2
    } ifelse (df$a[i] = df$round4[i]){
        df$x[i] = 3
    } ifelse (df$a[i] = df$round5[i]){
        df$x[i] = 4
    } ifelse (df$a[i] = df$round6[i]){
        df$x[i] = 5
    } ifelse (df$a[i] = df$round7[i]){
        df$x[i] = 6
    } 
}

所需的输出：

library(data.table)
df2 <- fread(
"round2 round3  round4  round5  round6  round7 a x 
8   12  18  32  40  36  32  4
6   12  18  24  30  36  30  5
8   16  18  24  30  36  18  3
4   12  12  24  30  36  24  4
6   16  24  32  40  48  24  3
8   12  18  24  30  36  30  5
8   12  18  24  30  36  18  3
8   16  24  32  40  48  40  5
8   16  24  24  30  48  48  6",
  header = TRUE
)

Answer 1

将df与a的值进行比较，然后通过将max.col指定为ties.method来使用"first"

max.col(df == df$a, ties.method = "first")
#[1] 4 5 3 4 3 5 3 5 6

将列条目与特定列选择的条目匹配

1 个答案: