Adding 2D array to 3D array within loop

2023 8 5
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I have a 3d array of zeros size (365,721,1440). I'm iterating through a for loop to add from array (721,1440) to the 3d array for each 1:365. Effectively, I'm wanting to do something like this:
totalarray(i,:,:)=totalarray(i,:,:)+newdata(:,:);
But obviously that throws me an error (Array dimensions must match for binary array op). Any idea how to add this new data I'm creating with each iteration to the total array?

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Stephen23
Stephen23 2023-8-6
移动：Stephen23 2023-8-6
The robust approach avoiding SQUEEZE is to use PERMUTE, e.g. inside the loop:
totalarray(i,:,:) = totalarray(i,:,:) + permute(newdata(:,:),[3,1,2]);

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Torsten
Torsten 2023-8-5
编辑：Torsten 2023-8-5
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totalarray = rand(365,721,1440);
newdata = rand(721,1440);
squeeze(totalarray(1,:,:))
ans = 721×1440
0.9180 0.7403 0.9442 0.6863 0.8394 0.5977 0.4434 0.9624 0.6240 0.7789 0.5832 0.5035 0.7979 0.4041 0.5983 0.3894 0.2274 0.2399 0.4560 0.0206 0.4144 0.6171 0.3203 0.0168 0.8789 0.5111 0.8552 0.4301 0.6461 0.6321 0.3525 0.9185 0.0988 0.5666 0.2365 0.2108 0.9625 0.1204 0.2400 0.8816 0.3561 0.6151 0.7968 0.7438 0.2618 0.6526 0.0194 0.4032 0.9423 0.4526 0.7445 0.3585 0.4404 0.9950 0.8167 0.2546 0.8617 0.3610 0.0185 0.5758 0.9099 0.9810 0.0050 0.4039 0.9070 0.7620 0.4528 0.9870 0.2616 0.4812 0.3090 0.8578 0.7012 0.6637 0.2347 0.4635 0.2407 0.8730 0.2824 0.5364 0.9783 0.8739 0.9082 0.3018 0.4118 0.5963 0.6822 0.5497 0.7222 0.2409 0.3404 0.3833 0.1079 0.3026 0.8795 0.7419 0.3381 0.9935 0.2534 0.3623 0.9849 0.8293 0.7670 0.3845 0.8292 0.2274 0.6246 0.7675 0.0875 0.8846 0.7229 0.9455 0.4574 0.2916 0.3537 0.2259 0.7163 0.4403 0.5925 0.4643 0.6796 0.7045 0.9304 0.4964 0.6210 0.7121 0.4238 0.1424 0.6906 0.6048 0.6481 0.9398 0.4049 0.9680 0.3860 0.8715 0.9419 0.8070 0.9225 0.9702 0.0564 0.5348 0.4018 0.1418 0.5718 0.6908 0.2867 0.7117 0.9550 0.3775 0.1733 0.4875 0.7058 0.4508 0.8729 0.5887 0.2104 0.4657 0.5697 0.8856 0.2466 0.1478 0.1918 0.4356 0.3903 0.4003 0.8102 0.7488 0.2213 0.8581 0.2131 0.1030 0.3792 0.1844 0.2401 0.7674 0.7793 0.0751 0.0511 0.0766 0.5268 0.5218 0.8256 0.8983 0.2225 0.4608 0.2592 0.3078 0.1806 0.0341 0.0125 0.7160 0.3720 0.0708 0.5327 0.7104 0.2295 0.4033 0.0143 0.1474 0.4705 0.9806 0.7691 0.7418 0.9536 0.7874 0.3542 0.1520 0.2379 0.2383 0.2001 0.0328 0.2337 0.3656 0.3641 0.6681 0.8772 0.4709 0.3654 0.2162 0.0318 0.2055 0.4044 0.9056 0.8325 0.3972 0.2610 0.6769 0.2282 0.9662 0.0612 0.8916 0.2086 0.3956 0.9327 0.9214 0.4151 0.4498 0.5307 0.4012 0.0485 0.0869 0.7273 0.9606 0.4810 0.1507 0.4744 0.7508 0.2955 0.3601 0.1234 0.0952 0.2242 0.0694 0.2134 0.0094 0.3020 0.3279 0.1929 0.0123 0.9108 0.1594 0.1994 0.0373 0.2910 0.1065 0.9818 0.2966 0.5297 0.6438 0.6840 0.3363 0.2713 0.3576 0.7629 0.2958 0.5539 0.6363 0.1863 0.6901 0.3004 0.1815 0.4398 0.0904 0.5276 0.3253 0.0399 0.4353 0.2279 0.3832 0.7812 0.5513 0.7459 0.2446 0.2601 0.1010 0.7443 0.7047 0.1154 0.9106
newdata
newdata = 721×1440
0.3055 0.9525 0.1939 0.5656 0.3264 0.4077 0.2867 0.1277 0.5417 0.2422 0.8504 0.9468 0.7681 0.7222 0.2938 0.2369 0.3955 0.9816 0.1759 0.6876 0.7899 0.3958 0.7094 0.3803 0.8130 0.1588 0.5729 0.1190 0.7107 0.0030 0.7729 0.7734 0.5378 0.1872 0.7650 0.7394 0.6198 0.8529 0.5647 0.4154 0.4782 0.8490 0.6765 0.5201 0.1543 0.8161 0.2849 0.8946 0.4749 0.2000 0.0452 0.4117 0.3485 0.5924 0.4287 0.2122 0.9401 0.2599 0.8172 0.8658 0.6798 0.8855 0.3265 0.2858 0.0643 0.3721 0.2426 0.4622 0.0092 0.4493 0.0270 0.8284 0.1620 0.8471 0.5345 0.2865 0.4786 0.2376 0.7596 0.4692 0.0854 0.4451 0.3848 0.2226 0.0683 0.8597 0.6666 0.9165 0.9614 0.1105 0.5993 0.9617 0.5919 0.0541 0.0755 0.3134 0.9879 0.8500 0.7821 0.4782 0.9411 0.2385 0.1511 0.4519 0.4333 0.8353 0.4779 0.8709 0.0190 0.0670 0.6135 0.0584 0.5449 0.1919 0.7425 0.1847 0.2467 0.8357 0.1343 0.6207 0.4026 0.3645 0.8392 0.0831 0.9765 0.8641 0.0740 0.2607 0.7417 0.9087 0.8713 0.7614 0.0320 0.9100 0.6449 0.5718 0.7865 0.9480 0.9700 0.2585 0.2334 0.9652 0.3249 0.8944 0.0340 0.0967 0.4310 0.8865 0.3138 0.6828 0.4058 0.8199 0.3658 0.2186 0.7358 0.8380 0.4910 0.7623 0.6318 0.1847 0.2507 0.2270 0.7121 0.1699 0.0554 0.1013 0.7941 0.2391 0.1909 0.1481 0.8970 0.7278 0.3771 0.1150 0.2383 0.5073 0.8240 0.8893 0.1994 0.6386 0.2944 0.3914 0.3253 0.4870 0.8307 0.2496 0.7897 0.4705 0.9255 0.9174 0.0917 0.9445 0.4681 0.3413 0.5292 0.8798 0.9710 0.8278 0.6057 0.9887 0.2685 0.6637 0.9822 0.5773 0.8273 0.1851 0.6225 0.5118 0.0222 0.5489 0.7444 0.7727 0.0729 0.2738 0.7131 0.0560 0.7964 0.8715 0.8032 0.8399 0.6415 0.7498 0.6395 0.3618 0.9688 0.5533 0.1456 0.1894 0.8611 0.4335 0.1508 0.5761 0.7659 0.0973 0.2885 0.7930 0.3601 0.5473 0.2266 0.0614 0.9997 0.9776 0.1400 0.0641 0.8306 0.5158 0.6687 0.4564 0.2149 0.5413 0.9368 0.5342 0.5678 0.6941 0.1299 0.2821 0.2538 0.5806 0.2616 0.7413 0.1544 0.8241 0.6549 0.8108 0.6849 0.6357 0.1402 0.3796 0.5517 0.7123 0.9054 0.4918 0.4470 0.6017 0.7618 0.5326 0.0907 0.8633 0.7658 0.2938 0.1662 0.6496 0.2920 0.4888 0.4386 0.4805 0.6625 0.9880 0.9101 0.7173 0.6183 0.6784 0.8134 0.0029 0.5616 0.3775 0.9112 0.7606 0.1493 0.3026
for i = 1:365
totalarray(i,:,:)=squeeze(totalarray(i,:,:))+newdata(:,:);
end
squeeze(totalarray(1,:,:))-newdata
ans = 721×1440
0.9180 0.7403 0.9442 0.6863 0.8394 0.5977 0.4434 0.9624 0.6240 0.7789 0.5832 0.5035 0.7979 0.4041 0.5983 0.3894 0.2274 0.2399 0.4560 0.0206 0.4144 0.6171 0.3203 0.0168 0.8789 0.5111 0.8552 0.4301 0.6461 0.6321 0.3525 0.9185 0.0988 0.5666 0.2365 0.2108 0.9625 0.1204 0.2400 0.8816 0.3561 0.6151 0.7968 0.7438 0.2618 0.6526 0.0194 0.4032 0.9423 0.4526 0.7445 0.3585 0.4404 0.9950 0.8167 0.2546 0.8617 0.3610 0.0185 0.5758 0.9099 0.9810 0.0050 0.4039 0.9070 0.7620 0.4528 0.9870 0.2616 0.4812 0.3090 0.8578 0.7012 0.6637 0.2347 0.4635 0.2407 0.8730 0.2824 0.5364 0.9783 0.8739 0.9082 0.3018 0.4118 0.5963 0.6822 0.5497 0.7222 0.2409 0.3404 0.3833 0.1079 0.3026 0.8795 0.7419 0.3381 0.9935 0.2534 0.3623 0.9849 0.8293 0.7670 0.3845 0.8292 0.2274 0.6246 0.7675 0.0875 0.8846 0.7229 0.9455 0.4574 0.2916 0.3537 0.2259 0.7163 0.4403 0.5925 0.4643 0.6796 0.7045 0.9304 0.4964 0.6210 0.7121 0.4238 0.1424 0.6906 0.6048 0.6481 0.9398 0.4049 0.9680 0.3860 0.8715 0.9419 0.8070 0.9225 0.9702 0.0564 0.5348 0.4018 0.1418 0.5718 0.6908 0.2867 0.7117 0.9550 0.3775 0.1733 0.4875 0.7058 0.4508 0.8729 0.5887 0.2104 0.4657 0.5697 0.8856 0.2466 0.1478 0.1918 0.4356 0.3903 0.4003 0.8102 0.7488 0.2213 0.8581 0.2131 0.1030 0.3792 0.1844 0.2401 0.7674 0.7793 0.0751 0.0511 0.0766 0.5268 0.5218 0.8256 0.8983 0.2225 0.4608 0.2592 0.3078 0.1806 0.0341 0.0125 0.7160 0.3720 0.0708 0.5327 0.7104 0.2295 0.4033 0.0143 0.1474 0.4705 0.9806 0.7691 0.7418 0.9536 0.7874 0.3542 0.1520 0.2379 0.2383 0.2001 0.0328 0.2337 0.3656 0.3641 0.6681 0.8772 0.4709 0.3654 0.2162 0.0318 0.2055 0.4044 0.9056 0.8325 0.3972 0.2610 0.6769 0.2282 0.9662 0.0612 0.8916 0.2086 0.3956 0.9327 0.9214 0.4151 0.4498 0.5307 0.4012 0.0485 0.0869 0.7273 0.9606 0.4810 0.1507 0.4744 0.7508 0.2955 0.3601 0.1234 0.0952 0.2242 0.0694 0.2134 0.0094 0.3020 0.3279 0.1929 0.0123 0.9108 0.1594 0.1994 0.0373 0.2910 0.1065 0.9818 0.2966 0.5297 0.6438 0.6840 0.3363 0.2713 0.3576 0.7629 0.2958 0.5539 0.6363 0.1863 0.6901 0.3004 0.1815 0.4398 0.0904 0.5276 0.3253 0.0399 0.4353 0.2279 0.3832 0.7812 0.5513 0.7459 0.2446 0.2601 0.1010 0.7443 0.7047 0.1154 0.9106

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Bruno Luong
Bruno Luong 2023-8-6
编辑：Bruno Luong 2023-8-6
I'm confused as a MATLAB beginner (!)
I though such assigment
totalarray(i,:,:)=squeeze(totalarray(i,:,:))+newdata(:,:);
would throw an error
"Unable to perform assignment because the size of the left side is 1-by-721-by-1440 and the size of the right side is 721-by-1440."
but obviously it's not.
Can someone points me to the official document that explain such assigment is allowed and how?
Torsten
Torsten 2023-8-6
编辑：Torsten 2023-8-6
Ran in:
Ran in:
Assigning an 1d row vector to the ith row of a matrix is the same thing:
v = rand(1,5);
M = zeros(3,5);
M(3,:) = v
M = 3×5
0 0 0 0 0 0 0 0 0 0 0.8197 0.2924 0.0199 0.8188 0.6605
Bruno Luong
Bruno Luong 2023-8-6
编辑：Bruno Luong 2023-8-6
Ran in:
Ran in:
Can you modify my (wrong) allowedassgn below so that it reflects correctly when the assignment
lhs = rhs
is allowed?
allowedassgn = @(lhs,rhs) isequal(size(lhs), size(rhs)) || ...
(isvector(lhs) && isvector(rhs) && length(lhs)==length(rhs)) || ...
(isempty(rhs) && isempty(lhs));
v = rand(1,5);
M = zeros(3,5);
allowedassgn(M(3,:), v)
ans = logical
1
M(3,:) = v; % so this is allowed
v = rand(5,1);
M = zeros(3,5);
allowedassgn(M(3,:), v) % idem
ans = logical
1
M(3,:) = v
M = 3×5
0 0 0 0 0 0 0 0 0 0 0.1687 0.1125 0.1724 0.9949 0.6670
v = rand(4,5);
M = zeros(3,4,5);
allowedassgn(M(3,:,:), v)
ans = logical
0
M(3,:,:) = v % but this works !!!
M =
M(:,:,1) = 0 0 0 0 0 0 0 0 0.6594 0.8731 0.3168 0.0578 M(:,:,2) = 0 0 0 0 0 0 0 0 0.2092 0.0008 0.4694 0.9609 M(:,:,3) = 0 0 0 0 0 0 0 0 0.1171 0.4693 0.2653 0.1701 M(:,:,4) = 0 0 0 0 0 0 0 0 0.3111 0.4261 0.2979 0.8661 M(:,:,5) = 0 0 0 0 0 0 0 0 0.4661 0.3910 0.2764 0.9486
Torsten
Torsten 2023-8-6
Maybe
allowedassgn = @(lhs,rhs) isequal(size(squeeze(lhs)), size(rhs)) || ...
(isvector(lhs) && isvector(rhs) && length(lhs)==length(rhs)) || ...
(isempty(rhs) && isempty(lhs));
?
Bruno Luong
Bruno Luong 2023-8-6
Ran in:
Ran in:
But
allowedassgn = @(lhs,rhs) isequal(size(squeeze(lhs)), size(rhs)) || ...
(isvector(lhs) && isvector(rhs) && length(lhs)==length(rhs)) || ...
(isempty(rhs) && isempty(lhs));
fails to detect
M = zeros(3,4,5);
v=rand(1,4,5);
allowedassgn(M(1,:,:),v)
ans = logical
0
M(1,:,:)=v; % But this works
Bruno Luong
Bruno Luong 2023-8-6
I think I'll ask in a separete question to get more visible to others

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