multidimensional-array

问题 I'm a beginner to numpy with no experience in matrices. I understand basic 1d and 2d arrays but I'm having trouble visualizing a 3d numpy array like the one below. How do the following python lists form a 3d array with height, length and width? Which are the rows and columns? b = np.array([[[1, 2, 3],[4, 5, 6]], [[7, 8, 9],[10, 11, 12]]]) 回答1: The anatomy of an ndarray in NumPy looks like this red cube below: (source: Physics Dept, Cornell Uni) Once you leave the 2D space and enter 3D or

问题 I'm a beginner to numpy with no experience in matrices. I understand basic 1d and 2d arrays but I'm having trouble visualizing a 3d numpy array like the one below. How do the following python lists form a 3d array with height, length and width? Which are the rows and columns? b = np.array([[[1, 2, 3],[4, 5, 6]], [[7, 8, 9],[10, 11, 12]]]) 回答1: The anatomy of an ndarray in NumPy looks like this red cube below: (source: Physics Dept, Cornell Uni) Once you leave the 2D space and enter 3D or

问题 Say I have a sorted numpy array: arr = np.array([0.0, 0.0], [0.5, 0.0], [1.0, 0.0], [0.0, 0.5], [0.5, 0.5], [1.0, 0.5], [0.0, 1.0], [0.5, 1.0], [1.0, 1.0]) and suppose I make a non trivial operation on it such that I have a new array which is the same as the old one but in another order: arr2 = np.array([0.5, 0.0], [0.0, 0.0], [0.0, 0.5], [1.0, 0.0], [0.5, 0.5], [1.0, 0.5], [0.0, 1.0], [1.0, 1.0], [0.5, 1.0]) The question is: how do you get the indices of where each element of arr2 are placed

问题 Good day, I've searched for this but haven't come up with any responses. I wish to send a multi dimensional numpy array over a socket. Hence, I decided to convert it to a string: However, it destroys the representation of the array: >>> import numpy as np >>> x = np.array([[0, 1], [2, 3]]) >>> xstring = x.tostring() >>> print xstring >>> print x [[0 1] [2 3]] >>> print xstring >>> nparr = np.fromstring(xstring, dtype=np.uint8) >>> print nparr [0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 3

问题 I am fetching the id, first name, and last name of all employees that are approved and not archived. Then I am looping these results and using the ids to query other tables to collect some count data. I tried the below code, but I am not getting the expected output. $queryEmp = " SELECT id, firstname, lastname FROM tbl_employee as e WHERE is_archive=0 and is_approved=1 "; $getQuery= $this->db->query($queryEmp); $result= $getQuery->result(); foreach ($result as $key=> $value) { //echo "<pre>";

问题 I am fetching the id, first name, and last name of all employees that are approved and not archived. Then I am looping these results and using the ids to query other tables to collect some count data. I tried the below code, but I am not getting the expected output. $queryEmp = " SELECT id, firstname, lastname FROM tbl_employee as e WHERE is_archive=0 and is_approved=1 "; $getQuery= $this->db->query($queryEmp); $result= $getQuery->result(); foreach ($result as $key=> $value) { //echo "<pre>";

问题 I have a 3D numpy array of shape (t, n1, n2) : x = np.random.rand(10, 2, 4) I need to calculate another 3D array y which is of shape (t, n1, n1) such that: y[0] = np.cov(x[0,:,:]) ...and so on for all slices along the first axis. So, a loopy implementation would be: y = np.zeros((10,2,2)) for i in np.arange(x.shape[0]): y[i] = np.cov(x[i, :, :]) Is there any way to vectorize this so I can calculate all covariance matrices in one go? I tried doing: x1 = x.swapaxes(1, 2) y = np.dot(x, x1) But

问题 How to remove row in two dimensional array in JavaScript with row number. If I want to delete all elements in row number 4 then how can do it?? 回答1: Here's an example of how to remove a row by using splice: var array = []; var count = 0; for (var row=0; row<4; row++) { array[row] = []; for (var col=0; col<5; col++) { array[row][col] = count++; } } console.log(array); [ [ 0, 1, 2, 3, 4 ], [ 5, 6, 7, 8, 9 ], [ 10, 11, 12, 13, 14 ], [ 15, 16, 17, 18, 19 ] ] function deleteRow(arr, row) { arr =

问题 I would like to create a miltidimentional array as follows so var multi-arr = [ ["A,2,5"], ["B,4,4"], ["C,4,4"] ] from string values gotten from the database using ajax. string data gotten from db delimited by # var string = "A,2,5# B,4,4# C,4,4"; I split the string by a '#' delimiter arr1=string.split(/\s*\#\s*/g); creating the array below var arr = ["A,2,5", "B,4,4", "C,4,4"]; I want to further split the items in the above array using the comma ',' as a delimiter and create a

问题 I would like to create a miltidimentional array as follows so var multi-arr = [ ["A,2,5"], ["B,4,4"], ["C,4,4"] ] from string values gotten from the database using ajax. string data gotten from db delimited by # var string = "A,2,5# B,4,4# C,4,4"; I split the string by a '#' delimiter arr1=string.split(/\s*\#\s*/g); creating the array below var arr = ["A,2,5", "B,4,4", "C,4,4"]; I want to further split the items in the above array using the comma ',' as a delimiter and create a