以气孔导度为例：

1 绘图代码：

p=linearfit(gs_wheat_yl_day(:,1),gs_wheat_yl_day(:,2));

[model_GPP_MLR,R2, RMSE]=R2_RMSE2(gs_wheat_yl_day(:,2),gs_wheat_yl_day(:,1))

[x y]=prepareCurveData(gs_wheat_yl_day(:,2),gs_wheat_yl_day(:,1));

rmse=sqrt(mean((x-y).^2));

formu=['R^2=',num2str(R2),'  RMSE=',num2str(rmse)]

plot(gs_wheat_yl_day(:,1),gs_wheat_yl_day(:,2),'b^','MarkerFaceColor','b')  %绘制每日gs的散点图

x=0.05; y=1.75;

text(x,y,formu,'color','b','FontSize',10)

hold on

plot(gs_wheat_yl_day(:,1),p(1).*gs_wheat_yl_day(:,1)+p(2),'b')   %散点图拟合直线

hold on 

q=linearfit(gs_wheat_yl_hour2(:,1),gs_wheat_yl_hour2(:,2));

[model_GPP_MLR,R2, RMSE]=R2_RMSE2(gs_wheat_yl_hour2(:,2),gs_wheat_yl_hour2(:,1))

[x y]=prepareCurveData(gs_wheat_yl_hour2(:,2),gs_wheat_yl_hour2(:,1));

rmse=sqrt(mean((x-y).^2));

formu=['R^2=',num2str(R2),'  RMSE=',num2str(rmse)]

plot(gs_wheat_yl_hour2(:,1),q(1).*gs_wheat_yl_hour2(:,1)+q(2),'r')  %每小时gs结果线性拟合

x=0.05; y=1.68;

text(x,y,formu,'color','r','FontSize',10)

hold on

plot(gs_wheat_yl_hour2(:,1),gs_wheat_yl_hour2(:,2),'ro')  %绘制每小时结果散点图

hold on

m=[0 1.8]; n=[0 1.8];

plot(m,n,'k-')

axis([0 1.8 0 1.8])

xlabel('Mete gs ( mol m^-^2 s^-^1 )')

ylabel('SIF gs ( mol m^-^2 s^-^1 )')

title('Yangling wheat site')

hold off

2 R2,RMSE拟合函数

function  [model_GPP_MLR,R2, RMSE]=R2_RMSE2(Prediction,measurement)

model_GPP_MLR = fitlm(Prediction,measurement);

R2=model_GPP_MLR.Rsquared.Ordinary;

RMSE = sqrt(sum((Prediction(:)-measurement(:)).^2) / numel(measurement) ); 

% rmse=sqrt(mean((x-y).^2));