Calculate the length of an interval if data are equal to zero-CodePudding

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!

CodePudding user response：

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.