On Mon, 3 Oct 2016, Frank S. wrote:
Dear R users,
[deleted]
I want to get a list of "k" data tables (or data frames) so that each
contains those individuals who for the first time are at least 65,
looping on each of the dates of vector "v". Let's consider the following
example with 5 individuals:
dt <- data.table(
id = 1:5,
fborn = as.Date(c("1935-07-25", "1942-10-05", "1942-09-07", "1943-09-07",
"1943-12-31")),
sex = as.factor(rep(c(0, 1), c(2, 3)))
)
v <- seq(as.Date("2006-01-01"), as.Date("2009-01-01"), by ="year") # k=4
I would expect to obtain k=4 data tables so that:
dt_p1: contains id = 1 (he is for the first time at least 65 on date v[1])
dt_p2: is NULL (no subject reach for the first time 65 on date v[2])
dt_p3: contains id = 2 & id = 3 (they are for the first time at least 65 on
v[3])
dt_p4: contains id = 4 & id = 5 (they are for the first time at least 65 on
v[4])
Here is a start (using a data.frame for dt):
vp <- as.POSIXlt( c( as.Date("1000-01-01"), v ))
vp$year <- vp$year-65
dt.cut <- as.numeric(cut(as.POSIXlt(dt$fborn),vp))
split(dt,factor(dt.cut, 1:length(v)))
$`1`
id fborn sex
1 1 1935-07-25 0
$`2`
[1] id fborn sex
<0 rows> (or 0-length row.names)
$`3`
id fborn sex
2 2 1942-10-05 0
3 3 1942-09-07 1
$`4`
id fborn sex
4 4 1943-09-07 1
5 5 1943-12-31 1
See
?as.POSIXlt
?cut.POSIXt
?split
HTH,
Chuck
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
