I have a dataframe with time points and the corresponding measure of the activity in different subjects. Each time point it’s a 5 minutes interval.
time Subject1 Subject2
06:03:00 6,682129 8,127075
06:08:00 3,612061 20,58838
06:13:00 0 0
06:18:00 0,9030762 0
06:23:00 0 0
06:28:00 0 0
06:33:00 0 0
06:38:00 0 7,404663
06:43:00 0 11,55835
...
I would like to calculate the length of each interval that contains zero activity, as the example below:
Subject 1 Subject 2
Interval_1 1 5
Interval_2 5
I have the impression that I should solve this using loops and conditions, but as I am not so experienced with loops I do not know where to start. Do you have any idea to solve this? Any help is really appreciated!
>Solution :
You can use rle() to find runs of consecutive values and the length of the runs. We need to filter the results to only runs where the value is 0:
result = lapply(df[-1], \(x) with(rle(x), lengths[values == 0]))
result
# $Subject1
# [1] 1 5
#
# $Subject2
# [1] 5
As different subjects can have different numbers of 0-runs, the results make more sense in a list than a rectangular data frame.