r - 如何检测和标记另一列中一列的变化

Question

我试图标记一个过程何时开始和结束。
代码需要检测更改何时开始和何时结束，并在另一列中进行标记。

示例数据:

date  process 
2007     0            
2008     1
2009     1
2010     1
2011     1
2012     1
2013     0

目标:

date  process        Status
2007     0             NA
2008     1        Process_START
2009     1             NA
2010     1             NA
2011     1             NA
2012     1        Process_END
2013     0             NA

Answer 1

也许通过计算 diff并在两个方向上滞后:

dif <- diff(df1$process)
df1$Status <- factor(c(NA, dif) - 2 * c(dif, NA), levels = -3:3)
levels(df1$Status) <- c(rep(NA, 4), "Start", "End", "Start&End")
#   date process Status
# 1 2007       0   <NA>
# 2 2008       1  Start
# 3 2009       1   <NA>
# 4 2010       1   <NA>
# 5 2011       1   <NA>
# 6 2012       1    End
# 7 2013       0   <NA>

更新

没有因素的版本:

dif <- diff(df1$process)
df1$Status <- c(NA, dif) - 2 * c(dif, NA)
df1$Status <- c(rep(NA,4), "Start", "End", "Start&End")[df1$Status + 4]

请注意，在单年流程的情况下，您会遇到“开始和结束”情况。

更新 2

如果系列以 process = 1 开始(或结束)，则预期输出可能不是 NA 而是开始(或结束):

dif <- diff(df1$process)
df1$Status <- c(df1$process[1], dif) - 2 * c(dif, -tail(df1$process,1))
df1$Status <- c(rep(NA,4), "Start", "End", "Start&End")[df1$Status + 4]

更复杂的例子:

set.seed(4)
df1 <- data.frame(date = 2007:(2007+24), process = sample(c(0,1, 1), 25, TRUE))

最后一个版本产生:

#    date process    Status
# 1  2007       1 Start&End
# 2  2008       0      <NA>
# 3  2009       0      <NA>
# 4  2010       0      <NA>
# 5  2011       1 Start&End
# 6  2012       0      <NA>
# 7  2013       1     Start
# 8  2014       1      <NA>
# 9  2015       1       End
# 10 2016       0      <NA>
# 11 2017       1 Start&End
# 12 2018       0      <NA>
# 13 2019       0      <NA>
# 14 2020       1     Start
# 15 2021       1      <NA>
# 16 2022       1      <NA>
# 17 2023       1      <NA>
# 18 2024       1      <NA>
# 19 2025       1      <NA>
# 20 2026       1      <NA>
# 21 2027       1      <NA>
# 22 2028       1      <NA>
# 23 2029       1      <NA>
# 24 2030       1      <NA>
# 25 2031       1       End