How can I display the y-axis at each maximum point

2 次查看（过去 30 天）
Muhammad Choudhury
Muhammad Choudhury 2021-4-29
评论： Muhammad Choudhury 2021-4-29
Is there a way in determining the y-axis values at each maximum point of this graph.
clear all;
% Importing video from files
vid = VideoReader('portfolio3/Tennis1.mp4');
% Converting the video into frames
frames = read(vid);
% Finding the size and length of the video
si = size(frames)
% % Creating a vector to store positions of the vector
posVec = [];
%% Cropping and greying the video for facile processing
% for all frames
for i = 1 : si(4)
% Cropping frame by frame
CroppedFrame = imcrop(frames(:,:,:,i),[120 90 450 1000]);
% Coverting to grey
CroppedFrame = rgb2gray(CroppedFrame);
% Binarising
CroppedFrame = im2bw(CroppedFrame,0.7);
% Removing flexes
CroppedFrame = imopen(CroppedFrame,strel('disk',3));
imshow(CroppedFrame);
% Tracking the ball in the video
[pos,rad] = imfindcircles(CroppedFrame,[13 100]);
viscircles(pos,rad);
drawnow
% Adding the current position to the position vector
posVec = [posVec; pos];
end
scatter(0-posVec(:,1),500-posVec(:,2));
pbaspect([1000 1000 1000])
hold on;
title('Bouncing Ball Trajectory')
xlabel('Horizontal Displacement')
ylabel('Vertical Displacement')

请先登录，再回答此问题。

采纳的回答

DGM
DGM 2021-4-29
编辑：DGM 2021-4-29
You can find the y-val and location of local maxima using findpeaks()
[peaks,loc,w] = findpeaks(mydata);
Just doing
findpeaks(mydata);
plots the series and places markers on the peaks that it found.
For example:
t = linspace(0,8.5*pi,100);
f = -t.^2.*sin(t) + t.^2;
[pk,loc]=findpeaks(f)
findpeaks(f)
gives
pk =
0.1809 51.69 249.62 604.93 1118.3
loc =
4 21 43 66 89
  3 个评论
显示 1更早的评论
DGM
DGM 2021-4-29
编辑：DGM 2021-4-29
You should just be running it on the y-data. Normally, you could run it on both x and y vectors, but your x-data isn't strictly increasing. Passing the y-data alone should be sufficient.
Consider this example using scattered data with non-monotonic x-data:
% plot points in a circle
r = 1;
th = linspace(0,2*pi,30);
x = r*cos(th);
y = r*sin(th);
scatter(x,y); axis equal
[pk,loc] = findpeaks(y)
findpeaks(y)
pk =
0.99853
loc =
8

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 Annotations 的更多信息

标签

产品


版本

R2020b

Community Treasure Hunt

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

Start Hunting!

Translated by