Extract data using ginput and fit with a formula of your choice

7 次查看（过去 30 天）
C A
C A 2021-6-15
评论： JJ Lamb 2021-6-16
I am choosing two end points using ginput [x,y] = ginput(2) and then I need to separate my data set which lies between the two end points. The separated data set must be fitted into the following formula.
y(1)*exp(-(x-x(1))/T)+y(2)
y(1),x(1),y(2) are the values taken from ginput. T is a parameter that I need to determine.
How can be done?
  3 个评论
显示 1更早的评论
C A
C A 2021-6-16
Yes, I already have a plot. I just need to fit the curve between the two points that I choose, instead of fitting the entire data set.

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

JJ Lamb
JJ Lamb 2021-6-16
I'm going to say that the input data for the graph is in a 2 column vector called "myData"
[x,y] = ginput(2);
% assuming you need points based on where you clicked on the x axis
xData = myData(x(1):x(2),1);
yData = myData(x(1):x(2),2);
myFun = @(T,x) y(1)*exp(-(x-x(1))/T)+y(2); % copied your function
TT = lsqcurvefit(myFun,1,xData,yData); % TT is the result of the curvefit
% the second input 1 is just an initial guess.
% might need to adjust it to a more reasonable starting point for your data
% Plot your results
figure
plot(xData,yData,'rx'); % original data
hold on
xx = min(xData):max(xData)-min(xData)/100:max(xData); % dummy variable for plotting
plot(xx,myFun(TT,xx),'b')
  2 个评论
C A
C A 2021-6-16
Thank you, may I ask why you have used 2 here (yData = myData(x(1):x(2),2)) instead of 1 ?
JJ Lamb
JJ Lamb 2021-6-16
I assumed that the y data was in the second column. Column 1 is x data, column 2 is y data. You may have them in separate variables already, in that case you would just need:
xData = oldX(x(1):x(2));
yData = oldY(x(1):x(2));

请先登录，再进行评论。

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Visual Exploration 的更多信息

标签

产品


版本

R2017a

Community Treasure Hunt

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

Start Hunting!

Translated by