Estimate the rate of change or first derivative of the raw mean daily streamflow or the smoothed cubic spline fit between time and mean daily streamflow.
Usage
rate_of_change(discharge, dates, smooth = TRUE)
Arguments
- discharge
numeric vector of mean daily discharges
- dates
vector of dates corresponding to daily discharge measurements.
Must be class "Date".
- smooth
logical indicating if the first derivative is calculated using a cubic smoothing spline function. Defaults is TRUE.
Value
Numeric vector with the estimated streamflow rate of change.
Examples
## calculate the first deriv of the smoothed function between Date and streamflow
rate <- rate_of_change(lavaca$Flow, lavaca$Date)
head(rate)
## Return the first deriv on raw measurements
rate2 <- rate_of_change(lavaca$Flow, lavaca$Date, smooth = FALSE)
head(rate2)