How can I work out the rate of change for my experimental data?

I have a set of experimental data I have plotted, I'd like a second graph demonstrating the rate of change of one of the variables. I have time against altitide, so the seocn graph is the rate of change of altitude (gradient of the first graph) against time. Please can people direct me to using the right code

Thank you

Answer 1

[Torsten]

rate_of_change_of_altitude = diff(altitude)./diff(time)