Hi,
I have a data.frame that contains a variable act which records the duration (in
seconds) of two states (wet-dry) for several individuals (identified by Ring)
over a period of time. Since I want to work with daytime (i.e. from sunrise
till sunset) and night time (i.e. from sunset till next sunrise), I have to
split act from time[i] till sunset and from sunset until time[i+1], and from
time[k] till sunrise and from sunrise until time[k+1].
Here is an example with time and act separated by a comma:
[i] 01-01-2000 20:55:00 , 360
[i+1] 01-01-2000 21:01:00 , 30 # let's say that sunset is at 01-01-2000 21:00:00
[i+2] 01-01-2000 21:01:30 , 30
.
.
.
My goal is to get:
[i] 01-01-2000 20:55:00 , 300 # act is modified
[i+1] 01-01-2000 21:00:00 , 60 # new row with time=sunset
[i+2] 01-01-2000 21:01:00 , 30 # previously row i+1th
[i+3] 01-01-2000 21:01:30 , 30 # previously row i+2th
.
.
.
I attach a dput with a selection of my data.frame. Here is a piece of existing
code that I am trying to adapt just for the daytime/night time change:
require(plyr)
xandaynight <- ddply( xan, .(Ring), function(df1){
# index of day/night changes
ind <- c( FALSE, diff(df$dif) == 1 )
add <- df1[ind,]
add$timepos <- add$dusk
# rearrangement
df1 <- rbind( df1, add )
df1 <- df1[order(df1$timepos),]
# recalculation of act
df1$act2 <- c( diff( as.numeric(df1$timepos) ), NA )
df1} )
This code produces an error message:
"Error en diff(df$dif): error in evaluating the argument 'x' in selecting a
method for function 'diff': Error en df$dif: object of type 'closure' is not a
subset"
Thank you for your help,
Santi______________________________________________
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