r - 如何在不同行中显示组名时聚合 data.frame

Question

我有一个像这样的 data.frame

df=data.frame(
grp=c("group1","s1","s2","s3","s4","s5","group2","s6","s7","s8","group2","s9","s10","group3","s11","s12","s13","s14"),
gname=c("gene1",0.00,0.05,0.01,0.01,0.01,"gene1",0.063,0.005,0.015,"gene2",0.07,0.00,"gene3",0.046,0.007,0.011,0.012),
score=c(0.989003844,NA,NA,NA,NA,NA,0.988334014,NA,NA,NA,0.983461712,NA,NA,0.982339339,NA,NA,NA,NA)
)

> df
      grp gname      score
1  group1 gene1 0.9890038
2      s1     0        NA
3      s2  0.05        NA
4      s3  0.01        NA
5      s4  0.01        NA
6      s5  0.01        NA
7  group2 gene1 0.9883340
8      s6 0.063        NA
9      s7 0.005        NA
10     s8 0.015        NA
11 group2 gene2 0.9834617
12     s9  0.07        NA
13    s10     0        NA
14 group3 gene3 0.9823393
15    s11 0.046        NA
16    s12 0.007        NA
17    s13 0.011        NA
18    s14 0.012        NA

根据组名和基因名，df可以分为4个部分。下图显示了这4个部分。



我要聚合df为每个部分找到max的 df$score和 length的 df$grp基于列 df$grp和 df$gname .以下 df 显示了预期结果。

grp     gname   max.score   length
group1  gene1   0.989003844   5
group2  gene1   0.988334014   3
group2  gene2   0.983461712   2
group3  gene3   0.982339339   4

下图显示了结果是如何获得的。


我该怎么表演aggregate(score~grp+gname,df,max)和 aggregate(grp~grp+gname,df,length)对于每个部分，并将结果保存在 data.frame 中。

Answer 1

如果您知道每个组以一个非缺失分数开始，然后是缺失值，那么组合 cumsum/is.na和 tapply会做的伎俩。

首先创建一个聚合变量 f .

f <- cumsum(!is.na(df$score))

现在看看结果长度是多少。最上面一行数字是 "names" 的值属性，长度是底行。这些长度包括 "group*"行，因此在最终数据帧中，减去 1。

tapply(f, f, length)
#1 2 3 4 
#6 4 3 5 

创建问题要求的结果。

result <- cbind(df[!is.na(df$score), ], length = tapply(f, f, length) - 1)

result
#      grp gname     score length
#1  group1 gene1 0.9890038      5
#7  group2 gene1 0.9883340      3
#11 group2 gene2 0.9834617      2
#14 group3 gene3 0.9823393      4

如果您还想要连续的行名，

row.names(result) <- NULL