查找條件y值的x軸位置

Question

我有大約180000個數據點，看起來像這樣 - Figure1。它的0和5以不規則的間隔。

data<- 0,0,0,5,5,5,0,0,0,5,5,5,0,0.. and so on. 

我想找到開始和結束的y值是5（用藍色標記）的索引。圖中附有圖。我正在使用R進行分析。我嘗試使用changepoint軟件包中的cpt.meanvar函數，但它並未提供所有更改點位置。有另一種方法嗎？

Answer 1

#DATA 
mydata<- c(0,0,0,5,5,5,0,0,0,5,5,5,0,0) 

#Find out which indices have 5 
v = which(mydata == 5) 

#Split into groups of consecutive integers and get the range for each sub-group 
lapply(split(v, cumsum(c(1, diff(v) != 1))), function(x) range(x)) 
#$`1` 
#[1] 4 6 

#$`2` 
#[1] 10 12 

在data.frame把可能更容易

setNames(data.frame(do.call(rbind, lapply(split(v, cumsum(c(1, diff(v) != 1))), 
              function(x) range(x)))), 
     c("Start", "End")) 
# Start End 
#1  4 6 
#2 10 12