multidimensional-array

问题 Considering an histogram of shape 100x100x100, I would like to find the 2 highest values a and b, and their indices (a1, a2, a3) and (b1, b2, b3), such as: hist[a1][a2][a3] = a hist[b1][b2][b3] = b We can easily get the highest value with hist.max(), but how can we get the X highest values in a ndarray? I understand that one normally uses np.argmax to retrieve the value indices, but in that case: hist.argmax().shape = () # single value for i in range(3): hist.argmax(i).shape = (100, 100) How

问题 Is the data in std::array<std::array<T,N>, M> guaranteed to be contiguous? For example: #include <array> #include <cassert> int main() { enum {M=4, N=7}; typedef std::array<char,N> Row; typedef std::array<Row, M> Matrix; Matrix a; a[1][0] = 42; const char* data = a[0].data(); /* 8th element of 1D data array should be the same as 1st element of second row. */ assert(data[7] == 42); } Is the assert guaranteed to succeed? Or, to put it another way, can I rely on there being no padding at the end

问题 i ve created two dimensional array inside a function, i want to return that array, and pass it somewhere to other function.. char *createBoard( ){ char board[16][10]; int j =0;int i = 0; for(i=0; i<16;i++){ for( j=0;j<10;j++){ board[i][j]=(char)201; } } return board; } but this keeps giving me error 回答1: Yeah see what you are doing there is returning a pointer to a object (the array called board ) which was created on the stack. The array is destroyed when it goes out of scope so the pointer

问题 How do I reorder the dimensions of an n dimensional array. For example, if I have a three dimensional array of sales data, where the first dimension represents the Date, the second dimension is the Store, and the third dimension is Department. How do I transform the array so that the first dimension is Store, the second is Department, and the third is Date. This is just an example. I am hoping for a general solution. 回答1: The function for doing that is aperm , from the base package. It is a

问题 I'm trying to create a list of categories with any number of sub categories, where sub categories can also has their own sub categories. I have selected all categories from the Mysql db, the cats are in a standard associate array list, each category has an id, name, parentid where the parentid is 0 if it's top level. I basically want to be able to take the single level array of cats and turn it into a multidimensional array structure where each category can have an element which will contain

问题 I have a multidimensional array called $songs, which outputs the following: Array ( [0] => Array ( [Michael Jackson] => Thriller ) [1] => Array ( [Michael Jackson] => Rock With You ) [2] => Array ( [Teddy Pendergrass] => Love TKO ) [3] => Array ( [ACDC] => Back in Black ) ) I would like to merge the arrays which have duplicate keys, so I can get the following: Array ( [0] => Array ( [Michael Jackson] => Array ( [0] => Thriller [1] => Rock With You ) ) [1] => Array ( [Teddy Pendergrass] =>

问题 In a program I'm writing the need to rotate a two-dimensional array came up. Searching for the optimal solution I found this impressive one-liner that does the job: rotated = zip(*original[::-1]) I'm using it in my program now and it works as supposed. My problem though, is that I don't understand how it works. I'd appreciate if someone could explain how the different functions involved achieves the desired result. 回答1: Consider the following two-dimensional list: original = [[1, 2], [3, 4]]

问题 I can't seem to find a simple, straight-forward solution to the age-old problem of removing empty elements from arrays in PHP. My input array may look like this: Array ( [0] => Array ( [Name] => [EmailAddress] => ) ) (And so on, if there's more data, although there may not be...) If it looks like the above, I want it to be completely empty after I've processed it. So print_r($array); would output: Array ( ) If I run $arrayX = array_filter($arrayX); I still get the same print_r output.

问题 I wonder if there's a possibility to create a two dimensional array and to quickly access any horizontal or vertical sub array in it? I believe we can access a horizontal sub array in the following case: x = Array.new(10) { Array.new(20) } x[6][3..8] = 'something' But as far as I understand, we cannot access it like this: x[3..8][6] How can I avoid or hack this limit? 回答1: There are some problems with 2 dimensional Arrays the way you implement them. a= [[1,2],[3,4]] a[0][2]= 5 # works a[2][0]

问题 I am trying to make an array with different lengths in a second dimension e.g.: A = 1 3 5 6 9 2 3 2 2 5 8 9 Is this possible? I've spent a fair amount of time looking but cannot find out either way. 回答1: Yes and no. First the no: Proper arrays in Fortran, such as those declared like this: integer, dimension(3,3,4) :: an_array or like this integer, dimension(:,:,:,:), allocatable :: an_array are regular; for each dimension there is only one extent. But, if you want to define your own type for