我之前问了一个类似的问题，但我需要一些进一步的输出，并决定发布一个新问题。
我有一个像这样的data.table对象：
library(data.table)
cells <- c(100, 1,1980,1,0,1,1,0,1,0,
150, 1,1980,1,1,1,0,0,0,1,
99 , 1,1980,1,1,1,1,0,0,0,
899, 1,1980,0,1,0,1,1,1,1,
789, 1,1982,1,1,1,0,1,1,1 )
colname <- c("number","sex", "birthy", "2004","2005", "2006", "2007", "2008", "2009","2010")
rowname <- c("1","2","3","4","5")
y <- matrix(cells, nrow=5, ncol=10, byrow=TRUE, dimnames = list(rowname,colname))
y <- data.table(y, keep.rownames = TRUE)
2004年专栏中的值1表示该人在2004年期间是连续投保的。被保险人在前3年可以参与该项研究。我需要这个data.table的子集，其中包含以下条件为真的所有观察：2004 + 2005 + 2006 = 3或2005 + 2006 + 2007 =或2006 + 2007 + ...
#using melt and rle function to restrucure the data
tmp <- melt(y, id = "rn", measure.vars = patterns("^20"),
variable.factor = FALSE, variable.name = "year")[, rle(value), by = rn]
#subset data based on condition, keeping only the first relevant sequence
tmp2 <- tmp[(values == 1 & lengths >= 3), .(rn,lengths)][, .SD[1,], by=rn]
##selecting only rows with value=1 and min 3 in a row
##keeping only the variable rn
tmp3 <- tmp[values == 1, which(max(lengths) >= 3), by = rn]$rn
##using the row-number to select obersvations from data.table
##merging length of sequence
dt <- merge(y[as.integer(tmp3)],tmp2, by="rn")
如果它们不是序列的一部分，有没有办法将所有1都变为0？例如，rn == 4变量“2005”需要为零。
我还需要一个新变量“begy”，其中包含序列开头的年份。例如rn==5和begy==2004。任何建议将不胜感激......
使用滚动窗口的选项：
#convert into long format and convert data types
DT <- melt(y, id="rn", measure.vars=patterns("^20"),
variable.factor=FALSE, variable.name="YEAR",
value.factor=FALSE, value.name="VALUE")
cols <- c("YEAR", "VALUE")
DT[, (cols) := lapply(.SD, as.integer), .SDcols=cols]
setorder(DT, rn, YEAR)
#for each row, sum the value that is between current year and 2 years from now
winsize <- 3L
DT[, roll3y := vapply(YEAR,
function(k) sum(VALUE[between(YEAR, k, k + winsize - 1L)]),
integer(1L)),
by=.(rn)]
#> Is there a way to turn all 1 to 0 if they are not part of a sequence?
#reset all values to 0 and set only those in sequence to 1
DT[, VALUE := 0L][
c(outer(DT[roll3y==winsize, which=TRUE], 0L:2L, `+`)), VALUE := 1L]
#> I also need a new variable "begy" containing the year of the beginning of the sequence.
#identify the year that a sequence of 3 ones appears
longDT <- rbindlist(list(DT,
DT[roll3y==winsize, .(YEAR="begy", VALUE=min(YEAR)), by=.(rn,number,sex,birthy)]),
use.names=TRUE, fill=TRUE)
#get desired output
dcast(longDT, rn + number + sex + birthy ~ YEAR, value.var="VALUE")
输出：
rn number sex birthy 2004 2005 2006 2007 2008 2009 2010 begy
1: 1 100 1 1980 0 0 0 0 0 0 0 NA
2: 2 150 1 1980 1 1 1 0 0 0 0 2004
3: 3 99 1 1980 1 1 1 1 0 0 0 2004
4: 4 899 1 1980 0 0 0 1 1 1 1 2007
5: 5 789 1 1982 1 1 1 0 1 1 1 2004
新解决方案：
# define a custom function in order to only keep the sequences
# with 3 (or more) consecutive years
rle3 <- function(x) {
r <- rle(x)
r$values[r$lengths < 3 & r$values == 1] <- 0
inverse.rle(r)
}
# replace all '1'-s that do not belong to a sequence of at least 3 to '0'
# create 'begy'-variable
melt(y, id = 1:4, measure.vars = patterns("^20"),
variable.factor = FALSE, variable.name = "year"
)[, value := rle3(value), by = rn
][, begy := year[value == 1][1], rn
][, dcast(.SD[!is.na(begy)], ... ~ year, value.var = "value")]
这使：
rn number sex birthy begy 2004 2005 2006 2007 2008 2009 2010 1: 2 150 1 1980 2004 1 1 1 0 0 0 0 2: 3 99 1 1980 2004 1 1 1 1 0 0 0 3: 4 899 1 1980 2007 0 0 0 1 1 1 1 4: 5 789 1 1982 2004 1 1 1 0 1 1 1
旧解决方案：
# define a custom function in order to only keep the sequences
# with 3 (or more) consecutive years
rle3 <- function(x) {
r <- rle(x)
r$values[r$lengths < 3 & r$values == 1] <- 0
inverse.rle(r)
}
# create a reference 'data.table' with only the row to keep
# and the start year of the (first) sequence (row 5 has 2 sequences of 3)
x <- melt(y, id = "rn", measure.vars = patterns("^20"),
variable.factor = FALSE, variable.name = "year"
)[, value := rle3(value), by = rn
][value == 1, .SD[1], rn]
# join 'x' with 'y' to add 'begy' and filter out the row with no sequences of 3
y[x, on = "rn", begy := year][!is.na(begy)]
这使：
rn number sex birthy 2004 2005 2006 2007 2008 2009 2010 begy 1: 2 150 1 1980 1 1 1 0 0 0 1 2004 2: 3 99 1 1980 1 1 1 1 0 0 0 2004 3: 4 899 1 1980 0 1 0 1 1 1 1 2007 4: 5 789 1 1982 1 1 1 0 1 1 1 2004
OP要求
1s变成0s，注意，第二个要求是不明确的，因为可能存在多于一个连续3年或更多年的序列，例如在第5行中。这里，我们取第一个（最老的）序列的开始年份。
解决方案如下
1s变成0s，如果它们不是连续3年或更多年的序列的一部分，begy），和无需滚动窗口或自定义功能。
library(data.table)
melt(y, , patterns("^\\d"))[
order(rn), N := .N, by = .(rleid(value), rn)][
value == 1 & N < 3, value := 0][
, begy := first(variable[value == 1]), by = rn][
, dcast(.SD[!is.na(begy), -"N"], ... ~ variable)]
rn number sex birthy begy 2004 2005 2006 2007 2008 2009 2010 1: 2 150 1 1980 2004 1 1 1 0 0 0 0 2: 3 99 1 1980 2004 1 1 1 1 0 0 0 3: 4 899 1 1980 2007 0 0 0 1 1 1 1 4: 5 789 1 1982 2004 1 1 1 0 1 1 1