Question

我的矢量看起来像这些变化：

cn1 <- c("Probe","Genes","foo","bar","Probe","Genes","foo","bar")
#          0        1      2     3      4      5       6    7

cn2 <- c("Probe","Genes","foo","bar","qux","Probe","Genes","foo","bar","qux")
#          0        1      2     3      4      5       6    7     8      9

请注意，上面的每个向量由两部分组成。它们以"Probe","Genes"分隔。我想要做的是获取该分隔符之间的条目的第一部分的索引。产生

cn1_id  ------> [2,3]
cn2_id  ------> [2,3,4]

我如何在R中实现这一目标？

我试过了，但它并没有做我想要的事情：

> split(cn1,c("Probe","Genes"))
$Genes
[1] "Genes" "bar"   "Genes" "bar"  

$Probe
[1] "Probe" "foo"   "Probe" "foo"

Answer 1

这是您可以使用的功能。请注意，R向量是基于1的，因此计数从1开始而不是0.

findidx <- function(x) {
    idx <- which(x=="Probe" & c(tail(x,-1),NA)=="Genes")
    if (length(idx)>1) {
        (idx[1]+2):(idx[2]-1)
    } else {
        NA # what to return if no match found
    }
}


findidx(cn1)
# [1] 3 4
findidx(cn2)
# [1] 3 4 5

Answer 2

您可以尝试between

中的data.table

indx <- between(cn1, 'Genes', 'Probe')
indx2 <- between(cn2, 'Genes', 'Probe')
which(cumsum(indx)==2)[-1]-1
#[1] 2 3

which(cumsum(indx2)==2)[-1]-1
#[1] 2 3 4

获取带有分隔部分的矢量索引

2 个答案: