slice

问题 I have large list of objects and I need to split them in a group of two elements for UI propouse. Example: [0, 1, 2, 3, 4, 5, 6] Becomes an array with these four arrays [[0, 1], [2, 3], [4, 5], [6]] There are a ton of ways to split an array. But, what is the most efficient (least costly) if the array is huge. 回答1: If you're looking for efficiency, you could have a method that would generate each array of 2 elements lazily, so you'd only store 2 elements at a time in memory: public struct

问题 I have large list of objects and I need to split them in a group of two elements for UI propouse. Example: [0, 1, 2, 3, 4, 5, 6] Becomes an array with these four arrays [[0, 1], [2, 3], [4, 5], [6]] There are a ton of ways to split an array. But, what is the most efficient (least costly) if the array is huge. 回答1: If you're looking for efficiency, you could have a method that would generate each array of 2 elements lazily, so you'd only store 2 elements at a time in memory: public struct

问题 I am trying to reverse slice of a list in python but it returns an empty list. But when I try with whole list, it works fine. Am I missing anything here? l=[1,2,3,4,5,6,7,8] l[::-1]=[8, 7, 6, 5, 4, 3, 2, 1] <<< This worked fine. l[2:5]=[3, 4, 5] l[2:5:-1]=[] <<< Expecting [5,4,3] here. Any clues? 回答1: The syntax is always [start:end:step] so if you go backwards your start needs to be greater than the end. Also remember that it includes start and excludes end, so you need to subtract 1 after

问题 I want to specify the frequency of markers that are printed in my scatter plot. After being unsuccessful with markevery (other stackoverflow question: Problems with using markevery) I followed the suggestion to slice my values using the notation of x[::5] and y[::5] for every 5th value. However, now I get a different error. That is, Traceback (most recent call last): File "C:\Users\mkupfer\NASA_SJSU_UARC_work\Info\CodingExamples\PythonExamples\X-Y-Value_Plot_Z-SimTime_02_noSectors.py", line

问题 In MATLAB it is common to slice out values that satisfy some condition from a matrix/array (called logical indexing). vec = [1 2 3 4 5]; condition = vec > 3; vec(condition) = 3; How do I do this in Eigen? So far I have: Eigen::Matrix<bool, 1, 5> condition = vec.array() > 3; 回答1: As pointed out in the answer to an similar question here: Submatrices and indices using Eigen, libigl adds this functionality to Eigen. igl::slice(A,indices,B); Is equivalent to B = A(indices) 回答2: Try this: #include

问题 I've seen three ways of writing content to HTTP response: func Handler(w http.ResponseWriter, req *http.Request) { io.WriteString(w, "blabla.\n") } And: func Handler(w http.ResponseWriter, r *http.Request) { w.Write([]byte("blabla\n")) } Also there's: fmt.Fprintf(w, "blabla") What's the difference between them? Which one is preferred to use? 回答1: io.Writer An output stream represents a target to which you can write sequence(s) of bytes. In Go this is captured by the general io.Writer

问题 Let's say I have 3 (or more) dimensional array A and two arrays with minimum and maximum edges left , right for slicing it. Is there a more compact notation than this to select the view delimited by my edges? V = A[left[0]:right[0], left[1]:right[1], left[2]:right[2]) Probably something like this is already better view = [ slice(a, b) for a,b in zip(left, right) ] V = A[view] but I feel there's a more numpythonic way I'm not seeing... don't know, something with np.s_ ? EDIT: an example of the

问题 In golang, slice and map are both reference types. When you simply need to modify elements in slice/map, the modification to slice/map members will be "broadcasted" to all slices. E.g, given m1 := make(map[int]int); m2 := m1 , m1[3] = 5 will lead to m2[3] == 5 . However, when you try to add new elements into these two types, things start to differ. As is shown in the example below, the new elements added into a map param will be shown automatically in the argument; however, the new elements

问题 practising some python, which is a pretty easy language to grab up. I have >>> L = [1,2,3,4] >>> L[1:1] = [1,2,3] >>> L [1, 1, 2, 3, 2, 3, 4] so on line two actually L[1:1] is empty list, but how can python understand that insert the [1,2,3] list to starting from 1 . I guess there is some internals which is not transparent to us, here apparently, I guess L[1:1] returns a reference to index 1 even if that returns an empty list... Best wishes, Umut 回答1: L[1:1] means the slice of the list L

问题 EDIT:I've changed the title, because the issue had nothing to do with IE image.load() firing - my substr() wasn't working (see accepted answer). There's a ton of posts about making sure that you define your onload handler prior to assigning img.src in order to guarantee that the onload handler is in place in case the image is loaded from cache first. This does not appear to the be issue in my code, since that's precisely what I have done. Note that this script works across all other browsers,