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are there other ways to write a multidimensional array in an array?


By : Andrew Miller
Date : September 16 2020, 02:00 AM
I think the issue was by ths following , I need to add an array to the array and I want to find the most convenient way for me. , Lets look at your two options...
Option 1
code :
// option 1
int& F = arr[1][0][1];
F = 2;
int& L = arr[2][0][F];   // added &
L = 5;
arr[1][0][1] = 2;
arr[2][0][2] = 5;
// option 2
arr[1][1][1] = 3;
int& Z = arr[2][1][arr[1][1][1]];
Z = 7;
arr[1][1][1] = 3;
arr[2][1][3] = 7;


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Ways to visualize how multidimensional array is laid in memory?


By : Adel Abdulal
Date : March 29 2020, 07:55 AM
Hope this helps Here's a way to think of your points[3][4] array. It is an array of 3 rows and 4 columns. The rows are numbered 0, 1, and 2, and the columns are numbered 0, 1, 2, and 3.
Let's populate the array with values, to help visualize it.
code :
      0  1  2  3
  --            --
0 |  11 12 13 14  |
1 |  21 22 23 24  |
2 |  31 32 33 34  |
  --            --
11 12 13 14 21 22 23 24 31 32 33 34
Address     Value
-------     -----
0012F5A4    11.0
0012F5AC    12.0
0012F5B4    13.0
0012F5BC    14.0
0012F5C4    21.0
0012F5CC    22.0
0012F5D4    23.0
0012F5DC    24.0
0012F5E4    31.0
0012F5EC    32.0
0012F5F4    33.0
0012F5FC    34.0
double *pd0 = points[0][1];
//-> error: incompatible type (cannot convert 'double' to 'double*' in initialization)
double *pd1 = &points[0][1];
//-> compatible type
double *pd2 = &points[5][2];
//-> compatible type (possible runtime error; points to the element out of bound)
double *pd3 = &**points;
//-> compatible type
double *pd3 = &(*(*points));
double (*p4d0)[4] = points[0];
//-> error: incompatible type (cannot convert 'double*' to 'double (*)[4]' in initialization)
double (*p4d1)[4] = &points[0];
//-> compatible type
double (*p4d2)[4] = (double (*)[4])points[0];
//-> compatible type

multidimensional array, different ways to represent address of grid[22][0]


By : Mehmet
Date : March 29 2020, 07:55 AM
it helps some times First of all, if you use %p, then you have to cast the values to (void*), because %p expects a expects a void pointer
code :
printf("%p\n", (void*) &ar[2][0]);
printf("%p\n", (void*) ar[2]);
printf("%p\n", (void*) &ar[2]);
&ar[2][0];
ar[2];
&ar[2];
printf("sizeof &ar[2][0]: %zu\n", sizeof &ar[2][0]);
printf("sizeof ar[2]:     %zu\n", sizeof ar[2]);
printf("sizeof &ar[2]:    %zu\n", sizeof &ar[2]);
sizeof &ar[2][0]: 8         (size of an pointer)
sizeof ar[2]:     12        (size of an array `int[3]`)
sizeof &ar[2]:    8         (size of a pointer)
void foo(int *x)
{
    (void) x; // to silence -Wall warnings
}
a.c: In function ‘main’:
a.c:21:6: warning: passing argument 1 of ‘foo’ from incompatible pointer type [-Wincompatible-pointer-types]
  foo(&ar[2]);
      ^
a.c:3:6: note: expected ‘int *’ but argument is of type ‘int (*)[3]’
 void foo(int *x)
      ^~~
void bar(int (*x)[3])
{
    (void) x;
}
int ar[3][3] = {
    {11, 22, 33},
    {44, 55, 66},
    {77, 88, 99}
};

Python iterate through a multidimensional numpy array in different ways


By : Sharath
Date : March 29 2020, 07:55 AM
Any of those help This is trivial to do with numpy using flatten and transpose as needed
code :
>>> import numpy as np
>>> A = np.array([["a", "b", "c"], 
                  ["d", "e", "f"],
                  ["g", "h", "i"]])
>>> A.flatten()
array(['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i'], dtype='<U1')
>>> A.T.flatten()
array(['a', 'd', 'g', 'b', 'e', 'h', 'c', 'f', 'i'], dtype='<U1')
>>> A.flatten()[::-1]
array(['i', 'h', 'g', 'f', 'e', 'd', 'c', 'b', 'a'], dtype='<U1')
>>> A.T.flatten()[::-1]
array(['i', 'f', 'c', 'h', 'e', 'b', 'g', 'd', 'a'], dtype='<U1')

Loop through multidimensional array and write to file for each parent array


By : kaine
Date : March 29 2020, 07:55 AM
wish helps you Figured it out...needed an additional grouped array to group the elements by the key in the nested array, in my case $sub['label'].
This isn't pretty or the most elegant but it works.
code :
<?php

$field_groups = acf_get_field_groups();

foreach( $field_groups as $field_group ) { 

    $acf_groups = acf_get_fields_by_id( $field_group['ID'] );

    $grouped = array();
    foreach ($acf_groups as $group) {
        $subs = $group['sub_fields'];

        foreach($subs as $sub) {
           $grouped[$group['label']][] = $sub['label'];
        }

        foreach ($grouped as $key => $items) {

            // print by group here.

        }

    }

}

In MATLAB how can I write out a multidimensional array as a string that looks like a raw numpy array?


By : achyuta26
Date : March 29 2020, 07:55 AM
should help you out I think it would be easier to just loop and use join. Your test cases pass.
code :
function out = bracketarray_matlabbit(in)

    out = permute(in, [2 1 3:ndims(in)]);
    out = string(out);

    dimsToCat = ndims(out);
    if iscolumn(out)
       dimsToCat = dimsToCat-1; 
    end

    for i = 1:dimsToCat
       out = "[" + join(out, ",", i) + "]"; 
    end
end
>> x = permute(reshape([1:16],2,2,2,2),[2,1,3,4]);

>> tic; for i = 1:1e4; bracketarray_matlabbit(x); end; toc
Elapsed time is 0.187955 seconds.

>> tic; for i = 1:1e4; bracketarray_cris_luengo(x); end; toc
Elapsed time is 5.859952 seconds.
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