Calculating trend rate of change

34 Ansichten (letzte 30 Tage)
Maja Zdulska
Maja Zdulska am 26 Jan. 2021
Kommentiert: Maja Zdulska am 26 Jan. 2021
Hi everyone,
I'm currently analysing a time series of data (see code below). I've fitted a trendline into it but I would like to calculate its rate of change per year. Any ideas how can it be done?
Thanks in advance,
Maja
%script to plot year-by-year data points for the full basin, fit a
%trendline and test it for significance with Mann-Whitney U test
%load data
data=readtable('Mydata.csv');
%define variables
year=data{:,1};
wind=data{:,8};
figure (1)
plot(year,wind,'b','LineWidth',1.2)
xlabel('\bf Year')
ylabel('\bf Wind speed (m/s)')
grid on
hold on
%fit a trendline to the data
wind_coeff=polyfit(year,wind,1);
wind_trend=polyval(wind_coeff,year);
plot(year,wind_trend,'r--','LineWidth',1.2);
%this bit tests the trend for significance with Mann-Whitney
%if p is very small and h=1, trend is significant
[p,h]=ranksum(year,netwind);

Akzeptierte Antwort

Bart Kieviet
Bart Kieviet am 26 Jan. 2021
Bearbeitet: Bart Kieviet am 26 Jan. 2021
I guess you mean the derivative? It's the function
diff
More on this function here.
  3 Kommentare
Bart Kieviet
Bart Kieviet am 26 Jan. 2021
If I understand correctly you have a year-by-year numbers, so say:
year = [2010, 2011, 2012, 2013];
wind = [10, 15, 5, 16];
if I run diff, I get:
df = diff(wind); % [5, -10, 11]
I could use mean to get the average:
mean( df ); % 2
Maja Zdulska
Maja Zdulska am 26 Jan. 2021
Ah, I wasn't sure whether I could just do it like that. Thanks a lot!

Melden Sie sich an, um zu kommentieren.

Weitere Antworten (0)

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by