Hello,
If I understand it well, this might avoid a loop.
dat <- read.table(text="
Salt time
1 35.65114 2003-07-19
2 35.64226 2003-07-20
3 35.62411 2003-07-21
4 35.62473 2003-07-22
5 35.65893 2003-07-23
6 35.70140 2003-07-24
7 35.62157 2003-07-25
8 35.64122 2003-07-26
9 35.63515 2003-07-27
10 35.63798 2003-07-28
", header = TRUE, stringsAsFactors = FALSE)
dat$time <- as.Date(dat$time)
change <- cumsum(c(FALSE, abs(diff(dat$Salt)) > 0.05))
split(dat, change)
Hope this helps,
Rui Barradas
Em 21-11-2012 16:39, Hefri escreveu:
Hi,
I have used R for some time, but managed to avoid writing loops. But this
time I am afraid there is no way around it.
I have a dataframe with time and salinity (see below). I would like to
extract the time intervals where salinity changes by less than 0.05. So
using the values below this would mean that a subset was made from
2003-07-19 to 2003-07-24, where the change in salinity exceeded 0.05, and
then stating again from 2003-07-24. In other words, I want to make subset of
the time intervals where the one variable stays stabile within a certain set
range.
head (D, 10)
Salt time
1 35.65114 2003-07-19
2 35.64226 2003-07-20
3 35.62411 2003-07-21
4 35.62473 2003-07-22
5 35.65893 2003-07-23
6 35.70140 2003-07-24
7 35.62157 2003-07-25
8 35.64122 2003-07-26
9 35.63515 2003-07-27
10 35.63798 2003-07-28
Is this possible? Can some please help with how I need to write the loop to
achieve this?
Many thanks, Helen
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