Computes and returns start date of each weather window, implemented in C++ for speed.
Arguments
- valid_periods
A data frame with a 'time' column (POSIXct).
- window_length
Minimum window duration (hours).
- allow_overlap
Logical; If TRUE, the algorithm searches for window, if a window is found, search of next window will start from the end of the previous window. If FALSE, it uses continuous window search: The algorithm searches for window starting from every time step that meets the criteria.
- time_step
Expected time step between consecutive timestamps (seconds).
