问题描述
我只是想在 MATLAB 中删除部分数据，例如： 如果我点击轴上的两个点，它会在我点击后相对于 x 轴切割元素。我将发布我的代码和图片以获取更多详细信息 提前致谢
load sample.mat
X = sample.current;
X1 = sample.voltage;
Ts = 0.01;
Fs = 1/Ts;
Fm = Fs/2;
Fc = 2;
N =10;
d = fdesign.lowpass('N,Fc',N,Fc,Fs);
designmethods(d);
Hd = design(d);
%fvtool(Hd)
%X is a variable form csv
%X1 is a variable from csv
output = filter(Hd,X);
output1 = filter(Hd,X1);
figure;
plot(X,X1,'-g');
hold on
plot(output,output1,'r');
hold off
legend('raw signal','filtered signal')
grid on
x = output,output1;
y = output1;
figure
subplot(2,1,1)
plot(x,y,'r');
title('Original plot');
uiwait(msgBox('Select an x-value from which to crop','modal'));
[x_user ~] = ginput(1); % Let the user select an x-value from which to crop.
x(x>x_user) = [];
subplot(2,2);
plot(x,'r');
title('New plot with cropped values');
xlim([min(x(:)) max(x(:))]);
解决方法
*将此作为格式代码的答案发布。
如果它只有一个图形，您可以使用“画笔/选择数据”（位于图形菜单栏上的带有红色方块的画笔图标）选择要删除的数据，然后选择要删除的点消失，然后按删除键。
如果你想用代码来做，你可以尝试使用以下方法找到信号开始在 X 上减小的点的索引：
% Find the index where X starts to decrease
maxIndex = find(data.x == max(data.x));
% In case of multiple indexs,ensure we get the first one
maxIndex = maxIndex(1);
% Copy data to new vector
saveData.x = data.x(1:maxIndex);
saveData.y = data.y(1:maxIndex);
如果你想使用用户的点击位置，你可以使用 find 来定位点击后第一个元素的索引：
% Get the coords of the first click
userFirstClick = ginput(1);
% Get the X component of the coords
xCoordInit = userFirstClick(1);
% Locate the index of the first element that is greater than
% the xCoord
firstXIndex = find(data.x >= xCoordInit);
% In case of multiple indexs,ensure we get the first one
firstXIndex = firstXIndex(1);
% Do the same to get the final index
userSecondClick = ginput(1);
xCoordFinal = userSecondClick(1);
finalXIndex = find(data.x > xCoordFinal);
finalXIndex = finalXIndex(1)-1;
% -1 because data.x(finalXIndex) is already greater than xCoordFinal
% Copy data to the new vector
saveData.x = data.x(firstXIndex:finalXIndex);
saveData.y = data.y(firstXIndex:finalXIndex);
然后只需绘制 saveData。
编辑
我之前的代码有一个错字，这里有一个功能齐全的示例，您只需单击要裁剪的两个点即可。
function cropSine()
% create a period of a Sine to initialize our data
data.x = -pi*3:0.01:pi*3;
data.y = sin(data.x);
% we make it loop back just as in your picture
data.x = [data.x,data.x(end:-1:1)];
data.y = [data.y,-data.y*0.5+5];
% create a figure to show the signal we have just created
figure
% create the axes where the data will be displayed
mainAx = axes();
% Draw our fancy sine!
plot(data.x,data.y,'b-','Parent',mainAx);
% Request the initial position to crop
userFirstClick = ginput(1);
% Get the index of the nearest point
initIndex = getNearest(userFirstClick,data);
% Do the same to get the final index
userSecondClick = ginput(1);
% Get the index of the nearest point
finalIndex = getNearest(userSecondClick,data);
% check if its a valid point
if isempty(initIndex) || isempty(finalIndex)
disp('No points in data vector!');
return;
end
% Ensure that final index is greater than first index
if initIndex > finalIndex
tempVal = initIndex;
initIndex = finalIndex;
finalIndex = tempVal;
end
% Copy the data that we want to save into a new variable
saveData.x = data.x(initIndex:finalIndex);
saveData.y = data.y(initIndex:finalIndex);
% Plot the cropped data in red!
hold(mainAx,'on');
plot(saveData.x,saveData.y,'r-',mainAx);
hold(mainAx,'off');
end
function nearestIndex = getNearest(clickPos,vector)
nearestIndex = [];
numPoints = length(vector.x);
if numPoints == 0
return;
end
nearestIndex = 1;
minDist = calcDist(vector.x(1),vector.y(1),clickPos(1),clickPos(2));
for pointID = 1:numPoints
dist = calcDist(vector.x(pointID),vector.y(pointID),clickPos(2));
if dist < minDist
nearestIndex = pointID;
minDist = dist;
end
end
end
function dist = calcDist(p1x,p1y,p2x,p2y)
dist = sqrt(power(p1x-p2x,2)+power(p1y-p2y,2));
end