slice

问题 I have an "empty" array that will be populated with data later in the code. But before it reaches that stage there's a section where the default content is copied to a temporary array, so the original can be changed and later receive the relevant data that was stored in the copy. The problem is when I use slice and delete the section in the original array, the temporary one is affected as well. var array1 = [["text", [[[1,2],[3,4],[5,6]]], 0]]; var array2 = array1[0].slice(0); //alert(array2

问题 I'm not sure I understand why this doesn't work : a = np.zeros((10, )) # first slicing array pos1 = np.zeros((10, ), dtype=np.bool) pos1[::2] = True a[pos1] = 1. print a # returns [ 1. 0. 1. 0. 1. 0. 1. 0. 1. 0.] # second slicing array pos2 = np.zeros((5, ), dtype=np.bool) pos2[::2] = True a[pos1][pos2] = 2. print a # still returns [ 1. 0. 1. 0. 1. 0. 1. 0. 1. 0.] why does the second slicing didn't affect the full array? I thought a[pos1] was just a "view" of the subpart of the original array

问题 Iv'e got an problem. Please help me what is wrong. There is my code : (function () { var app = angular.module('store', ['ui.bootstrap']); app.controller('StoreController', function ($scope, $http) { $scope.pageSize = 20; $scope.currentPage = 1; $http.get("../scripts/products.php").success(function (data) { $scope.products = data; }); }).filter('startFrom', function () { return function (data, start) { return data.slice(start); }; }); })(); And HTML : <div class="col-md-2 product " ng-hide=

问题 I have an input stream that looks something like this: data = [[1,234],[2,432],[3,443]] I'm trying to figure the best way to get the second element of every list. I can easily get the second value of a single entry by something like data[0][1] , or every list in a range with both elements by using data[0:2] , but I can't for the life of me figure out how to get just the second element from every array, short of processing every element independently through an array and making a new one on

问题 If I have a n dimensional array it can be sliced by a m * n matrix like this a <- array(1:27,c(3,3,3)) b <- matrix(1:3,3,3) # This will return the index a[1,1,1] a[2,2,2] and a[3,3,3] # That is one result for each row in the b matrix a[b] # Output [1] 1 14 27 In the above example the array a is sliced the same way as if it was sliced by each row in the b matrix and the result was combined. Is there any "effective and easy" way to do a similar slice but to keep some dimensions free? That is

问题 I'm trying to make a palette swap functionality for a game, and I'm trying to find a way to change the color of pixels of a certain color to another. I've been able to make all of the pixels the same color with this function I found in a tutorial: def color_surface(self,surface, red, green, blue): arr = pygame.surfarray.pixels3d(surface) arr[:,:,0] = red arr[:,:,1] = green arr[:,:,2] = blue As far as I can tell, the first two indices are the location of the pixel, and the third is the color

问题 I am reading a vendor-provided large binary array into a 2D numpy array tempfid(M, N) # load data data=numpy.fromfile(file=dirname+'/fid', dtype=numpy.dtype('i4')) # convert to complex data fid=data[::2]+1j*data[1::2] tempfid=fid.reshape(I*J*K, N) and then I need to reshape it into a 4D array useful4d(N,I,J,K) using non-trivial mappings for the indices. I do this with a for loop along the following lines: for idx in range(M): i=f1(idx) # f1, f2, and f3 are functions involving / and % as well

问题 This question already has answers here : Subsetting a 2D numpy array (4 answers) Closed 4 years ago . I have a numpy array (we'll call it test) of ~286 x 181 x 360, and need to extract a 3-D array from it. The ranges needed for the three dimensions are defined as other numpy arrays (a_dim, b_dim, and c_dim) (based ultimately on user input). Naively, I had hoped I'd be able to do something like big_array[a_dim,b_dim,c_dim]. That ran happily when the b_dim and c_dim contained only a single

问题 I want to understand slicing with timeseries in Pandas and I am looking at the possibility of combining in a logical statement (combining and , or, not operands) conditions involving dates. So this is a reproducible example: HAO_10 Date Price 2018-01-02 30.240000 2018-01-03 30.629999 2018-01-04 30.860001 2018-01-05 31.010000 2018-01-08 31.389999 2018-01-09 31.309999 2018-01-10 31.400000 2018-01-11 31.580000 2018-01-12 31.680000 2018-01-16 31.200001 HAO_10.iloc[((HAO_10.index < datetime

问题 Swift 3 has upTo and through which are noninclusive, inclusive respectively func prefix(upTo: Int) Returns a subsequence from the start of the collection up to, but not including , the specified position. . func prefix(through: Int) Returns a subsequence from the start of the collection through the specified position. for the other end it has from func suffix(from: Int) Returns a subsequence from the specified position to the end of the collection. which seems to be inclusive What's the non