Marking the peak of a plot automatically without having to click on it

2012 8 29
4 个回答
回答已采纳
更新时间：2021 3 28
25 次查看（30 天）

1 个投票

Hi,
Is it possible to mark the peak of a plot automatically with a command without having to to mark on each plot.

请先登录，再回答此问题。

 采纳的回答

Star Strider
Star Strider 2012-8-29
编辑：Star Strider 2012-8-29

1 个投票

If you have the Signal Processing Toobox, I suggest the findpeaks function with two outputs so that you get the value of the function at the peak as well as the index of your x-variable at which the peak occurs.
For example:
[Peak, PeakIdx] = findpeaks(Y);
and the label would then be:
text(x(PeakIdx), Peak, sprintf('Peak = %6.3f', Peak));
using the text command.
To illustrate:
X = [0:0.1:pi]';
Y = sin(X);
[Peak, PeakIdx] = findpeaks(Y);
figure(1)
plot(X, Y)
text(X(PeakIdx), Peak, sprintf('Peak = %6.3f', Peak))

1 个评论
显示 -1更早的评论 隐藏 -1更早的评论

Kiki
Kiki 2016-3-29
Hi
What if I have multiple peaks and I want the apply the label respectively? How should I write the text command?
Thank you!

请先登录，再进行评论。

更多回答（3 个）

Wayne King
Wayne King 2012-8-29

2 个投票

Do you know the value of the peak?, then yes, it's easy.
x = randn(100,1);
[val,I] = max(x);
plot(x); hold on;
plot(I,val,'r^','markerfacecolor',[1 0 0])

7 个评论
显示 5更早的评论 隐藏 5更早的评论

Lisa Justin
Lisa Justin 2012-8-29
编辑：Lisa Justin 2012-8-29
no i do not know the values of the peak, i want the value at the peak to also be visible. Same as using the data cursor on a plot directly. it a bunch of signals and i want to run a script on all, i would also like my script to mark the peaks automatically so i do not need to mark each plot before saving
Tom
Tom 2012-8-29
are you looking for one single maximum value, or are you looking for local peaks (i.e. the peaks of a sine wave where there can be several per plot)?
Tom
Tom 2012-8-29
Then Wayne's code above should work fine.
Lisa Justin
Lisa Justin 2012-8-29
But the value is not displayed on the plot with Wayne's code
Tom
Tom 2012-8-29
It should be; can you provide some sample data?

请先登录，再进行评论。

Ilham Hardy
Ilham Hardy 2012-8-29

0 个投票

4 个评论
显示 2更早的评论 隐藏 2更早的评论

Lisa Justin
Lisa Justin 2012-8-29
编辑：Lisa Justin 2012-8-29
I also need the value at that peak to be displayed. Same as using the data cursor on a plot to mark points. but i want the data cursor to mark the peaks in my plot automatically so i do not need to mark it directly
Jan
Jan 2012-8-29
Then use the output of the peakfinder and a simple TEXT command.
Lisa Justin
Lisa Justin 2012-8-29
thanks, but what do you mean by simple TEXT command

请先登录，再进行评论。

类别

在 帮助中心 和 File Exchange 中查找有关 Descriptive Statistics 的更多信息

标签

Community Treasure Hunt

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

Start Hunting!

Translated by