matrix

问题 I need help in math in general for euler angles and specifically in ARKit. I looked at many references for calculation of euler angles but I wondered why apple in its tutorial calculated yaw from atan2(r11, r12) as follow: let yaw = atan2f(camera.transform.columns.0.x, camera.transform.columns.1.x) If I need to calculate pitch or roll, for example how? I need to understand yaw and why they not always depends on yaw = camera.eularAngle.y Please check this code and questions in comments, I'm

问题 I have translated a view using onTouchEvent , And then I have rotated that view with input value like 90 degree. Now I wanted to scale that view without affecting previous translation and rotation, by using following code I retained rotation, but not translation. val scaleValue = 1.2f val px = rectf.centerX() val py = rectf.centerY() matrix.reset() matrix.setScale(scaleValue, scaleValue, px, py) matrix.postRotate(rotateAngle, px, py) Update 1 val scaleFactor = 0.02f val scaleValue = value *

问题 I have translated a view using onTouchEvent , And then I have rotated that view with input value like 90 degree. Now I wanted to scale that view without affecting previous translation and rotation, by using following code I retained rotation, but not translation. val scaleValue = 1.2f val px = rectf.centerX() val py = rectf.centerY() matrix.reset() matrix.setScale(scaleValue, scaleValue, px, py) matrix.postRotate(rotateAngle, px, py) Update 1 val scaleFactor = 0.02f val scaleValue = value *

问题 Problem Statement: Given a matrix of people(denoted by small alphabets) and bikes(denoted by capital alphabets), find the nearest bike for a given person. How will you change your solution if you have to find bikes for a set of people? (assuming multiple bikes can be at the same distance from 1 person)? I know Dijkstra's algorithm and Bellman Ford's algorithm, but curious about the implementation here. Or can it be solved by BFS(Breadth First Search)? 回答1: To assign a single bike to a single

问题 Problem Statement: Given a matrix of people(denoted by small alphabets) and bikes(denoted by capital alphabets), find the nearest bike for a given person. How will you change your solution if you have to find bikes for a set of people? (assuming multiple bikes can be at the same distance from 1 person)? I know Dijkstra's algorithm and Bellman Ford's algorithm, but curious about the implementation here. Or can it be solved by BFS(Breadth First Search)? 回答1: To assign a single bike to a single

问题 How to return a set of rows of a NumPy Matrix that would match a given condition? This is a Numpy Matrix object >>> X matrix([['sunny', 'hot', 'high', 'FALSE'], ['sunny', 'hot', 'high', 'TRUE'], ['overcast', 'hot', 'high', 'FALSE'], ['rainy', 'mild', 'high', 'FALSE'], ['rainy', 'cool', 'normal', 'FALSE'], ['rainy', 'cool', 'normal', 'TRUE'], ['overcast', 'cool', 'normal', 'TRUE'], ['sunny', 'mild', 'high', 'FALSE'], ['sunny', 'cool', 'normal', 'FALSE'], ['rainy', 'mild', 'normal', 'FALSE'], [

问题 My situation is: I get a 1000*2 matrix and a 1000*1 vector. And the row i in the matrix is mapped to the element i in the vector. And the elements in the vector are all integer. Now I want to sort the elements in the vector from low to high. And I want to get a new matrix with the sequence of the new vector. And the mapping relationships are equal to the original situation. How to do this in Matlab? Thanks! 回答1: Use sortrows: First concat your vector to your matrix: M2 = [V, M]; Then sort

问题 My situation is: I get a 1000*2 matrix and a 1000*1 vector. And the row i in the matrix is mapped to the element i in the vector. And the elements in the vector are all integer. Now I want to sort the elements in the vector from low to high. And I want to get a new matrix with the sequence of the new vector. And the mapping relationships are equal to the original situation. How to do this in Matlab? Thanks! 回答1: Use sortrows: First concat your vector to your matrix: M2 = [V, M]; Then sort

问题 My situation is: I get a 1000*2 matrix and a 1000*1 vector. And the row i in the matrix is mapped to the element i in the vector. And the elements in the vector are all integer. Now I want to sort the elements in the vector from low to high. And I want to get a new matrix with the sequence of the new vector. And the mapping relationships are equal to the original situation. How to do this in Matlab? Thanks! 回答1: Use sortrows: First concat your vector to your matrix: M2 = [V, M]; Then sort

问题 I have a vector of distances which I get from some other procedure and want to convert it to a dist object in the R language . Below I give an example how such a vector looks like : distVector is computed in the same way said other procedure computes the distance vector. Ideally, I would like to transform this vector into a distance matrix ( dist object) without wasting resources. I think I could just transform it to a matrix by copying it as upper triangular and lower triangular matrix,