I would like to calculate a new variable "acceleration (in m/s^2)" for longitudinal recorded car data and only have the speed of the car(in m/s) and the recording time (in s).
This is a part of the dataframe df:
speed time_sec
1 27.520 0.273
2 27.520 0.313
3 27.172 0.353
4 26.887 0.393
5 26.560 0.433
6 26.560 0.473
How could I add a new variable "acceleration (positive values)/ deceleration (negative values)" to every recording row of the car?
This is basically delta speed divided by delta time. So use diff twice and don't forget the first value is not computable from the data.
c(NA, with(cars, diff(speed)/diff(time_sec)))
#[1] NA 0.000 -8.700 -7.125 -8.175 0.000
cars$accel <- c(NA, with(cars, diff(speed)/diff(time_sec)))
Data.
cars <- read.table(text = "
speed time_sec
1 27.520 0.273
2 27.520 0.313
3 27.172 0.353
4 26.887 0.393
5 26.560 0.433
6 26.560 0.473
", header = TRUE)