r - 计算交替列之间的长度

Question

我想弄清楚如何计算从一列为 True 到另一列为 True 的行数。我尝试使用游程编码，但无法弄清楚如何从每一列中获取交替值。

set.seed(42)
s<-sample(c(0,1,2,3),500,replace=T)
isOverbought<-s==1
isOverSold<-s==0
head(cbind(isOverbought,isOverSold),20)
res<-rle(isOverSold)
tt<-res[res$values==0] #getting when Oversold is true

 > head(cbind(isOverbought,isOverSold))

[1,]        FALSE      FALSE
[2,]        FALSE      FALSE
[3,]         TRUE      FALSE <-starting condition is overbought
[4,]        FALSE      FALSE
[5,]        FALSE      FALSE
[6,]        FALSE      FALSE
[7,]        FALSE      FALSE
[8,]        FALSE       TRUE <-is oversold. length from overbought to oversold = 5
[9,]        FALSE      FALSE
[10,]        FALSE      FALSE
[11,]         TRUE      FALSE <- is overbought. length from oversold to overbought = 3
[12,]        FALSE      FALSE
[13,]        FALSE      FALSE
[14,]         TRUE      FALSE
[15,]         TRUE      FALSE
[16,]        FALSE      FALSE
[17,]        FALSE      FALSE
[18,]        FALSE       TRUE <-is oversold. length from overbought to oversold = 7
[19,]         TRUE      FALSE <- is overbought. length from oversold to overbought = 1 
[20,]        FALSE      FALSE

目标

overboughtTOoversold oversoldTOoverbought
5                     3
7                     1

Answer 1

这足以解决您的问题。

## `a` to `b`
a2b <- function (a, b) {
  x <- which(a)    ## position of `TRUE` in `a`
  y <- which(b)    ## position of `TRUE` in `b`
  z <- which(a | b)   ## position of all `TRUE`
  end <- match(y, z)    ## match for end position
  start <- c(1L, end[-length(end)] + 1L)    ## start position
  valid <- end > start  ## remove cases with `end = start`
  z[end[valid]] - z[start[valid]]
  }

## cross `a` and `b`
axb <- function (a, b) {
  if (any(a & b))
    stop ("Invalid input! `a` and `b` can't have TRUE at the same time!")
  x <- a2b(a, b); y <- a2b(b, a)
  if (which(a)[1L] < which(b)[1L]) cbind(a2b = x, b2a = c(NA_integer_, y))
  else cbind(a2b = c(NA_integer_, x), b2a = y)
  }

---

对于您的isOverbought 和isOverSold，我们获得:

result <- axb(isOverbought, isOverSold)

head(result)
#     a2b b2a
#[1,]   5  NA
#[2,]   7   3
#[3,]   3   1
#[4,]   8   5
#[5,]   2   6
#[6,]  10   2

因为 isOverbought 在 isOverSold 之前有第一个 TRUE，所以第二列的第一个元素是 NA。