ellipse

问题 So, I have ellipses given - they are defined by their midpoint, an horizontal radius(rh) and an vertical radius(rv). I'm drawing them using sin/cos and the result looks fairly good to me(just making sure this isn't an error source). Now say I have an angle(or a direction vector) given and I want to have the point on the ellipse's outline with that angle/direction. My intuitive approach was to simply use the direction vector, normalise it and multiply its x-component with rh, its y-component

问题 So, I have ellipses given - they are defined by their midpoint, an horizontal radius(rh) and an vertical radius(rv). I'm drawing them using sin/cos and the result looks fairly good to me(just making sure this isn't an error source). Now say I have an angle(or a direction vector) given and I want to have the point on the ellipse's outline with that angle/direction. My intuitive approach was to simply use the direction vector, normalise it and multiply its x-component with rh, its y-component

问题 G'day. I am plotting a pca with the factoextra package. I have 3 points for each factor and would like to draw ellipses around each. But I am getting the error Too few points to calculate an ellipse . It is possible to draw ellipses around 3 points in ggplot2 with the stat_ellipse function. I can confirm this by looking at the calculate_ellipse code from ggplot2 that says else if (dfd < 3) {message("Too few points to calculate an ellipse") . So what ellipse function is factoextra using in

问题 I am trying to fit an ellipse over my different sets of 2D points using matplotlib. I'm using the ellipse fitting functions from here, and here's the code. from matplotlib.patches import Ellipse import matplotlib.pyplot as plt import numpy def fitEllipse(x,y): x = x[:,np.newaxis] y = y[:,np.newaxis] D = np.hstack((x*x, x*y, y*y, x, y, np.ones_like(x))) S = np.dot(D.T,D) C = np.zeros([6,6]) C[0,2] = C[2,0] = 2; C[1,1] = -1 E, V = eig(np.dot(inv(S), C)) n = np.argmax(np.abs(E)) a = V[:,n]

问题 I'm trying to fit an ellipse to a set of points described by x and y coordinates. I found a detailed explanation of how to do it here http://nicky.vanforeest.com/misc/fitEllipse/fitEllipse.html and tried out the code, but it doesn't seem to work. It finds the center correctly, but the angle and axes are completely wrong, as you can see in this image: https://i.imgur.com/VLEeNKQ.png The red points are my data points and the blue aptch is an ellipse drawn from the obtained parameters. Now, the

问题 I'm trying to fit an ellipse to a set of points described by x and y coordinates. I found a detailed explanation of how to do it here http://nicky.vanforeest.com/misc/fitEllipse/fitEllipse.html and tried out the code, but it doesn't seem to work. It finds the center correctly, but the angle and axes are completely wrong, as you can see in this image: https://i.imgur.com/VLEeNKQ.png The red points are my data points and the blue aptch is an ellipse drawn from the obtained parameters. Now, the

问题 I have created an ellipse using matplotlib.patches.ellipse as shown below: patch = mpatches.Ellipse(center, major_ax, minor_ax, angle_deg, fc='none', ls='solid', ec='g', lw='3.') What I want is a list of all the integer coordinates enclosed inside this patch. I.e. If I was to plot this ellipse along with every integer point on the same grid, how many of those points are enclosed in the ellipse? I have tried seeing if I can extract the equation of the ellipse so I can loop through each point

问题 I am trying to sample around 1000 points from a 3-D ellipsoid, uniformly. Is there some way to code it such that we can get points starting from the equation of the ellipsoid? I want points on the surface of the ellipsoid. 回答1: Here is a generic function to pick a random point on a surface of a sphere, spheroid or any triaxial ellipsoid with a, b and c parameters. Note that generating angles directly will not provide uniform distribution and will cause excessive population of points along z

问题 Small disclaimer: This is my first time messing with Graphics in Forms, therefore I am not so familiar with the concepts here Alright, so I have been trying to make an application that tracks the cursor's position in the entire screen and draws an Ellipse around it. The code I borrowed was from this question (I changed the X and Y position of the Ellipse in order to auto-adjust itself around the cursor regardless of its size) everything works perfectly up to this point. Here is the code so

问题 I'm having trouble to find the best way to draw the below shape. I'm using the below code to draw an Ellipse on visual layer. But how can I only brush the quarters? I think it can be done using LinearGradientBrush or RadialGradientBrush but I don't know how use it. var cntrpoint = space.FlipYAxis(x2, y2); dc.DrawEllipse(Brushes.Transparent, pen, cntrpoint, 30, 30); 回答1: Like this: var geometry = new GeometryGroup(); geometry.Children.Add(new RectangleGeometry(new Rect(1, 0, 1, 1))); geometry