matrix | 易学教程

TypeError: object array may be self-referencing python

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问题 So, I ran into this error: temp7: 1.68219771725e-06 temp6: [[array([-60800056.33037408], dtype=object)]] Exception in thread Thread-4: Traceback (most recent call last): File "/usr/lib/python2.7/threading.py", line 810, in __bootstrap_inner self.run() File "/opt/ros/indigo/lib/python2.7/dist-packages/rospy/timer.py", line 223, in run self._callback(TimerEvent(last_expected, last_real, current_expected, current_real, last_duration)) File "/home/husky/catkin_ws/src/huskybot_ekf_v2/src/meas

Matrix formalism NxN adjacency matrix

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问题 Let A be the NxN adjacency matrix of an undirected unweighted network, without self-loops. Let 1 be a column vector of N elements, all equal to 1. In other words 1 = (1, 1, ..., 1)T , where the superscript T indicates the transpose operation. Use the matrix formalism (multiplicative constants, multiplication row by column, matrix operations like transpose and trace, etc, but avoid the sum symbol Σ) to write expressions for: a)The vector k whose elements are the degrees ki of all nodes i = 1,

Compare or align 3D objects [closed]

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问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 2 years ago . I have two 3D matrices. Each pixel is a gray scale value. The first 3D matrix is a reference shape. e.g. imagine a 3D model of a mouth. The second 3D matrix is an approximate subsection of the reference shape. e.g. imagine a tooth. The subsection is approximate as it is from a different mouth. Note the

extract a column from text file

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问题 I have a a text file (huge amount of float numbers) with 25 columns. I want to extract column 14 and divide it by column 15. I could not extract this two columns. Codes: with open('sample for north.txt') as infile: for line in infile: print(line.split()[13]) Error : list index out of range 回答1: You are getting the error Error : list index out of range because there aren't enough columns (at least on the given line). It's better to check, something along this line: with open('sample for north

Why a row of my matrix is a list? R

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问题 I got a list of matrices X rows by 2 columns, called list_of_matrices_by2 list_of_matrices_by2[1:3] [[1]] [,1] [,2] [1,] "7204" "d" [2,] "7204" "a" [[2]] [,1] [,2] [1,] "2032" "b" [2,] "2032" "e" [3,] "2032" "a" [[3]] [,1] [,2] [1,] "802" "d" [2,] "802" "b" I want to stack all my matrices in a all_pairs matrix, so I did this all_pairs=do.call(rbind,list_of_matrices_by2) all_pairs[1:10] [,1] [,2] [1,] "7204" "d" [2,] "7204" "a" [3,] "2032" "b" [4,] "2032" "e" [5,] "2032" "a" [6,] "802" "d" [7,

Android 变形矩阵——Matrix

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对于图像的色彩处理，Android系统提供了ColorMatrix颜色矩阵来帮助我们进行图像处理。而对于图像的图形变化，Android系统也是通过来进行处理的，每个像素点都表达了其坐标的X、Y信息。Android的图形变换矩阵是一个3x3的矩阵，如图（1）所示。当使用变换矩阵去处理每一个像素点的时候，与颜色矩阵的矩阵乘法一样，计算公式如下所示。 X1 = a * X + b * Y + c Y1 = d * X + e * Y + f l = g * X + h * Y + i 通常情况下，会让g=h=0，i=1，这是使 l = g * x + h *y + i恒成立。因此，只需要关注上面几个参数就可以了。与色彩变换矩阵的初始矩阵一样，图像变换矩阵也有一个初始矩阵。很明显，就是对直角元素a、e、i我1，其他元素我0的矩阵，如图（2）所示。图像的变化处理通常包含以下四类基本变化 ● Translate——平移变换 ● Rotate——选择变换 ● Scale——缩放变换 ● Skew——错切变换 ▶ 平移变换平移变换的坐标值变换过程如图（3）所示，即将每个像素点都进行平移变换。当从p（X0，Y0）平移到p（X，Y），坐标值发送了如下所示的变换 X = X0 + △X Y = Y0 + △Y 如果写成矩阵形式就是如图（4）所示。通过技计算可发现如下等式。 X = X0 +

Subsetting a matrix using a vector of indices

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问题 Suppose I have a matrix of values, and a vector which tells me, for each row of the matrix, which (one!) column I'd like to access. How, without a loop, do I retrieve those values? Data: dta <- structure(c(0.02, 0.01, 0, 0.08, 0.18, 0.01, 0.12, 0, 0.03, 0, 0.95, 0.96, 0.94, 0.97, 0.98, 0.95, 0.99, 0.91, 0.96, 0.98, 0.98, 0.99, 1, 0.92, 0.82, 0.99, 0.88, 1, 0.97, 1, 0.05, 0.04, 0.06, 0.03, 0.02, 0.05, 0.01, 0.09, 0.04, 0.02), .Dim = c(20L, 2L), .Dimnames = list(NULL, c("1", "2"))) Vector of

expand matrix in matlab?

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问题 I would like to expand matrix row by row under a conditional statement without initializing the matrix. In C++, simply I use std::vector and push_back method without initializing the size of the vector in C++. However, I want to do same scenario in Matlab. This is my pseudo code for i = 1:lengt(data) if ( condition ) K = [data(1) data(2) i] end K 回答1: If we assume from the above that data is an Nx2 matrix, and that you only want to save the rows that satisfy some condition, then you almost

Splitting non-continuous sized matrix in vectors

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问题 I'm writing an piece of software within Matlab. Here, the user can define a dimension say 3. This dimension is subsequently the number of iterations of a for loop. Within this loop, I construct a matrix to store the results which are generated during every iteration. So, the data of every iteration is stored in a row of a matrix. Therefore, the size of the matrix depends on the size of the loop and thus the user input. Now, I want to separate each row of this matrix (cl_matrix) and create

matrix multiplication result value range

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问题 Here is the initial question: About the output value range of LeGall 5/3 wavelet Today I found actually the transform can be seen as a matrix multiplication. It is easy to calculate the wavelet coefficients as a matrix (in order to estimate the value, all the Rounded down action is ignored which will not affect the estimation of the max value). The 1st level of DWT2 has two steps which is to perform the LeGall 5/3 filter on two directions. If we see the I as the input 8*8 matrix and A as the