R 计算特定列上的行平均值

每个样本我有六个复制品。我想计算列读数的每个样本id的平均值。我想保留样本id和读数的平均值。数据如下所示

Sample  Replicate   Number  Reading
S_1     1   1   7
S_1     2   2   7
S_1     3   1   7
S_1     4   2   9
S_1     5   1   9
S_1     6   2   7
S_2     1   1   6
S_2     2   2   6
S_2     3   1   9
S_2     4   2   9
S_2     5   1   9
S_2     6   2   9
S_3     1   1   1
S_4     2   2   1
S_5     3   1   1
S_6     4   2   1
S_7     5   1   2
S_8     6   2   1

所以我应该

Sample Reading(mean)
S_1
S-2
..
S_8

---

test您可以使用
aggregate

aggregate(Reading~Sample,data=yourdata, mean)

arr
aggregate(Reading~Sample,data=yourdata, mean)

arr <- tapply(dframe$Reading, dframe$Sample, mean)

tableFrame <- data.frame(Sample = names(arr), "Reading(mean)" = arr, check.names=FALSE)