Could this work for you? It may be too "sample specific" instead working for every example.
This script generates a 4D array A of random numbers, and an array sigma of indices (which you provided). It then uses these indices to extract elements from A along the fourth dimension, and saves the results in a new array B, creating a new 3D array that only contains the elements of A selected by the sigma array.
sub2ind function needs same length vectors, so it's been workarounded a bit.
A = rand(10,25,7,10);
sigma = [5,5,4,1,1,9,8,7,2,4];
idx = sub2ind(size(A), repmat((1:10)',25*7,1), ...
repmat(reshape(repmat((1:25)',1,7),[],1),10,1), ...
repmat(reshape(repmat((1:7)',25,1),[],1),10,1), ...
repmat(sigma',25*7,1));
B = reshape(A(idx), [10, 25, 7]);
disp(B)
(:,:,1) =
Columns 1 through 19
0.8419 0.1654 0.4302 0.0222 0.1194 0.4118 0.8931 0.6330 0.7192 0.4322 0.2011 0.2726 0.9072 0.1600 0.8224 0.5720 0.2752 0.6638 0.9715
0.1068 0.2722 0.2647 0.3641 0.5543 0.1652 0.7239 0.3740 0.8143 0.3968 0.7299 0.7016 0.2639 0.0332 0.9909 0.0442 0.9355 0.4878 0.3770
0.1411 0.5408 0.4414 0.0513 0.8026 1.0000 0.0751 0.5718 0.8551 0.5188 0.3871 0.0247 0.1508 0.5312 0.5501 0.1578 0.6124 0.7138 0.7429
0.3241 0.2109 0.7512 0.1503 0.8854 0.9613 0.2702 0.2072 0.3297 0.1601 0.5885 0.8163 0.7043 0.2722 0.3613 0.4253 0.2086 0.1753 0.7646
0.9964 0.0846 0.2339 0.6096 0.4706 0.6881 0.8045 0.1918 0.5795 0.3290 0.7296 0.9661 0.8417 0.4322 0.3425 0.8539 0.1077 0.4708 0.4340
0.5386 0.4330 0.4899 0.2925 0.3641 0.7586 0.9642 0.9607 0.5449 0.2362 0.3217 0.0573 0.5500 0.5746 0.0740 0.8235 0.1572 0.2822 0.3274
0.4756 0.8898 0.5960 0.0507 0.0921 0.1475 0.1726 0.9654 0.9958 0.4072 0.4900 0.9518 0.4734 0.7550 0.4443 0.7000 0.9827 0.4097 0.2692
0.6074 0.0632 0.8178 0.9912 0.7856 0.1898 0.9194 0.8009 0.5920 0.4843 0.8502 0.5559 0.3164 0.8014 0.0337 0.2448 0.6822 0.9138 0.1172
0.7617 0.0669 0.1958 0.1749 0.5044 0.0657 0.3261 0.2607 0.5235 0.2774 0.3124 0.7538 0.7401 0.2160 0.3764 0.1029 0.6114 0.0423 0.9861
0.0539 0.0552 0.0603 0.1992 0.8039 0.2940 0.6013 0.1736 0.8238 0.6903 0.4683 0.0435 0.2153 0.3781 0.3374 0.2396 0.0657 0.8695 0.4397
Columns 20 through 25
0.0297 0.0033 0.2927 0.4264 0.1332 0.2415
0.2785 0.1678 0.4385 0.4717 0.4377 0.0106
0.3901 0.6661 0.8665 0.8876 0.7462 0.0204
0.7250 0.7851 0.9598 0.5317 0.9935 0.3177
0.3933 0.3303 0.7820 0.7344 0.4992 0.7589
0.6290 0.5364 0.9495 0.8766 0.1682 0.5318
0.1893 0.4017 0.1995 0.4424 0.5875 0.8294
0.7882 0.0410 0.4026 0.0419 0.3005 0.2005
0.8363 0.2756 0.6467 0.7691 0.9012 0.1762
0.3174 0.3921 0.7081 0.0927 0.6641 0.8973
(:,:,2) =
Columns 1 through 19
0.7295 0.9767 0.9107 0.1318 0.7118 0.9255 0.6909 0.4158 0.2962 0.7614 0.8419 0.1654 0.4302 0.0222 0.1194 0.4118 0.8931 0.6330 0.7192
0.5105 0.3614 0.6143 0.7640 0.8465 0.8773 0.4293 0.6849 0.2809 0.3280 0.1068 0.2722 0.2647 0.3641 0.5543 0.1652 0.7239 0.3740 0.8143
0.5359 0.8440 0.4746 0.5335 0.3952 0.7718 0.3380 0.0489 0.8560 0.7551 0.1411 0.5408 0.4414 0.0513 0.8026 1.0000 0.0751 0.5718 0.8551
0.3204 0.1051 0.8214 0.3956 0.1964 0.0831 0.2789 0.0179 0.6262 0.8167 0.3241 0.2109 0.7512 0.1503 0.8854 0.9613 0.2702 0.2072 0.3297
0.0027 0.0980 0.0290 0.3765 0.0310 0.8001 0.7793 0.5528 0.4243 0.4869 0.9964 0.0846 0.2339 0.6096 0.4706 0.6881 0.8045 0.1918 0.5795
0.6930 0.7368 0.3657 0.7719 0.1206 0.0464 0.1892 0.8462 0.6369 0.9851 0.5386 0.4330 0.4899 0.2925 0.3641 0.7586 0.9642 0.9607 0.5449
0.6023 0.9826 0.5895 0.4044 0.6841 0.8209 0.3883 0.0739 0.0371 0.8075 0.4756 0.8898 0.5960 0.0507 0.0921 0.1475 0.1726 0.9654 0.9958
0.7721 0.1879 0.2124 0.6136 0.5076 0.1983 0.1037 0.2933 0.7815 0.2867 0.6074 0.0632 0.8178 0.9912 0.7856 0.1898 0.9194 0.8009 0.5920
0.0809 0.2578 0.1787 0.9215 0.9610 0.9895 0.7791 0.6516 0.1358 0.7782 0.7617 0.0669 0.1958 0.1749 0.5044 0.0657 0.3261 0.2607 0.5235
0.8553 0.3136 0.3753 0.0828 0.3849 0.4778 0.2705 0.3805 0.5815 0.8126 0.0539 0.0552 0.0603 0.1992 0.8039 0.2940 0.6013 0.1736 0.8238
Columns 20 through 25
0.4322 0.2011 0.2726 0.9072 0.1600 0.8224
0.3968 0.7299 0.7016 0.2639 0.0332 0.9909
0.5188 0.3871 0.0247 0.1508 0.5312 0.5501
0.1601 0.5885 0.8163 0.7043 0.2722 0.3613
0.3290 0.7296 0.9661 0.8417 0.4322 0.3425
0.2362 0.3217 0.0573 0.5500 0.5746 0.0740
0.4072 0.4900 0.9518 0.4734 0.7550 0.4443
0.4843 0.8502 0.5559 0.3164 0.8014 0.0337
0.2774 0.3124 0.7538 0.7401 0.2160 0.3764
0.6903 0.4683 0.0435 0.2153 0.3781 0.3374
(:,:,3) =
Columns 1 through 19
0.5720 0.2752 0.6638 0.9715 0.0297 0.0033 0.2927 0.4264 0.1332 0.2415 0.7295 0.9767 0.9107 0.1318 0.7118 0.9255 0.6909 0.4158 0.2962
0.0442 0.9355 0.4878 0.3770 0.2785 0.1678 0.4385 0.4717 0.4377 0.0106 0.5105 0.3614 0.6143 0.7640 0.8465 0.8773 0.4293 0.6849 0.2809
0.1578 0.6124 0.7138 0.7429 0.3901 0.6661 0.8665 0.8876 0.7462 0.0204 0.5359 0.8440 0.4746 0.5335 0.3952 0.7718 0.3380 0.0489 0.8560
0.4253 0.2086 0.1753 0.7646 0.7250 0.7851 0.9598 0.5317 0.9935 0.3177 0.3204 0.1051 0.8214 0.3956 0.1964 0.0831 0.2789 0.0179 0.6262
0.8539 0.1077 0.4708 0.4340 0.3933 0.3303 0.7820 0.7344 0.4992 0.7589 0.0027 0.0980 0.0290 0.3765 0.0310 0.8001 0.7793 0.5528 0.4243
0.8235 0.1572 0.2822 0.3274 0.6290 0.5364 0.9495 0.8766 0.1682 0.5318 0.6930 0.7368 0.3657 0.7719 0.1206 0.0464 0.1892 0.8462 0.6369
0.7000 0.9827 0.4097 0.2692 0.1893 0.4017 0.1995 0.4424 0.5875 0.8294 0.6023 0.9826 0.5895 0.4044 0.6841 0.8209 0.3883 0.0739 0.0371
0.2448 0.6822 0.9138 0.1172 0.7882 0.0410 0.4026 0.0419 0.3005 0.2005 0.7721 0.1879 0.2124 0.6136 0.5076 0.1983 0.1037 0.2933 0.7815
0.1029 0.6114 0.0423 0.9861 0.8363 0.2756 0.6467 0.7691 0.9012 0.1762 0.0809 0.2578 0.1787 0.9215 0.9610 0.9895 0.7791 0.6516 0.1358
0.2396 0.0657 0.8695 0.4397 0.3174 0.3921 0.7081 0.0927 0.6641 0.8973 0.8553 0.3136 0.3753 0.0828 0.3849 0.4778 0.2705 0.3805 0.5815
Columns 20 through 25
0.7614 0.8419 0.1654 0.4302 0.0222 0.1194
0.3280 0.1068 0.2722 0.2647 0.3641 0.5543
0.7551 0.1411 0.5408 0.4414 0.0513 0.8026
0.8167 0.3241 0.2109 0.7512 0.1503 0.8854
0.4869 0.9964 0.0846 0.2339 0.6096 0.4706
0.9851 0.5386 0.4330 0.4899 0.2925 0.3641
0.8075 0.4756 0.8898 0.5960 0.0507 0.0921
0.2867 0.6074 0.0632 0.8178 0.9912 0.7856
0.7782 0.7617 0.0669 0.1958 0.1749 0.5044
0.8126 0.0539 0.0552 0.0603 0.1992 0.8039
(:,:,4) =
Columns 1 through 19
0.4118 0.8931 0.6330 0.7192 0.4322 0.2011 0.2726 0.9072 0.1600 0.8224 0.5720 0.2752 0.6638 0.9715 0.0297 0.0033 0.2927 0.4264 0.1332
0.1652 0.7239 0.3740 0.8143 0.3968 0.7299 0.7016 0.2639 0.0332 0.9909 0.0442 0.9355 0.4878 0.3770 0.2785 0.1678 0.4385 0.4717 0.4377
1.0000 0.0751 0.5718 0.8551 0.5188 0.3871 0.0247 0.1508 0.5312 0.5501 0.1578 0.6124 0.7138 0.7429 0.3901 0.6661 0.8665 0.8876 0.7462
0.9613 0.2702 0.2072 0.3297 0.1601 0.5885 0.8163 0.7043 0.2722 0.3613 0.4253 0.2086 0.1753 0.7646 0.7250 0.7851 0.9598 0.5317 0.9935
0.6881 0.8045 0.1918 0.5795 0.3290 0.7296 0.9661 0.8417 0.4322 0.3425 0.8539 0.1077 0.4708 0.4340 0.3933 0.3303 0.7820 0.7344 0.4992
0.7586 0.9642 0.9607 0.5449 0.2362 0.3217 0.0573 0.5500 0.5746 0.0740 0.8235 0.1572 0.2822 0.3274 0.6290 0.5364 0.9495 0.8766 0.1682
0.1475 0.1726 0.9654 0.9958 0.4072 0.4900 0.9518 0.4734 0.7550 0.4443 0.7000 0.9827 0.4097 0.2692 0.1893 0.4017 0.1995 0.4424 0.5875
0.1898 0.9194 0.8009 0.5920 0.4843 0.8502 0.5559 0.3164 0.8014 0.0337 0.2448 0.6822 0.9138 0.1172 0.7882 0.0410 0.4026 0.0419 0.3005
0.0657 0.3261 0.2607 0.5235 0.2774 0.3124 0.7538 0.7401 0.2160 0.3764 0.1029 0.6114 0.0423 0.9861 0.8363 0.2756 0.6467 0.7691 0.9012
0.2940 0.6013 0.1736 0.8238 0.6903 0.4683 0.0435 0.2153 0.3781 0.3374 0.2396 0.0657 0.8695 0.4397 0.3174 0.3921 0.7081 0.0927 0.6641
Columns 20 through 25
0.2415 0.7295 0.9767 0.9107 0.1318 0.7118
0.0106 0.5105 0.3614 0.6143 0.7640 0.8465
0.0204 0.5359 0.8440 0.4746 0.5335 0.3952
0.3177 0.3204 0.1051 0.8214 0.3956 0.1964
0.7589 0.0027 0.0980 0.0290 0.3765 0.0310
0.5318 0.6930 0.7368 0.3657 0.7719 0.1206
0.8294 0.6023 0.9826 0.5895 0.4044 0.6841
0.2005 0.7721 0.1879 0.2124 0.6136 0.5076
0.1762 0.0809 0.2578 0.1787 0.9215 0.9610
0.8973 0.8553 0.3136 0.3753 0.0828 0.3849
(:,:,5) =
Columns 1 through 19
0.9255 0.6909 0.4158 0.2962 0.7614 0.8419 0.1654 0.4302 0.0222 0.1194 0.4118 0.8931 0.6330 0.7192 0.4322 0.2011 0.2726 0.9072 0.1600
0.8773 0.4293 0.6849 0.2809 0.3280 0.1068 0.2722 0.2647 0.3641 0.5543 0.1652 0.7239 0.3740 0.8143 0.3968 0.7299 0.7016 0.2639 0.0332
0.7718 0.3380 0.0489 0.8560 0.7551 0.1411 0.5408 0.4414 0.0513 0.8026 1.0000 0.0751 0.5718 0.8551 0.5188 0.3871 0.0247 0.1508 0.5312
0.0831 0.2789 0.0179 0.6262 0.8167 0.3241 0.2109 0.7512 0.1503 0.8854 0.9613 0.2702 0.2072 0.3297 0.1601 0.5885 0.8163 0.7043 0.2722
0.8001 0.7793 0.5528 0.4243 0.4869 0.9964 0.0846 0.2339 0.6096 0.4706 0.6881 0.8045 0.1918 0.5795 0.3290 0.7296 0.9661 0.8417 0.4322
0.0464 0.1892 0.8462 0.6369 0.9851 0.5386 0.4330 0.4899 0.2925 0.3641 0.7586 0.9642 0.9607 0.5449 0.2362 0.3217 0.0573 0.5500 0.5746
0.8209 0.3883 0.0739 0.0371 0.8075 0.4756 0.8898 0.5960 0.0507 0.0921 0.1475 0.1726 0.9654 0.9958 0.4072 0.4900 0.9518 0.4734 0.7550
0.1983 0.1037 0.2933 0.7815 0.2867 0.6074 0.0632 0.8178 0.9912 0.7856 0.1898 0.9194 0.8009 0.5920 0.4843 0.8502 0.5559 0.3164 0.8014
0.9895 0.7791 0.6516 0.1358 0.7782 0.7617 0.0669 0.1958 0.1749 0.5044 0.0657 0.3261 0.2607 0.5235 0.2774 0.3124 0.7538 0.7401 0.2160
0.4778 0.2705 0.3805 0.5815 0.8126 0.0539 0.0552 0.0603 0.1992 0.8039 0.2940 0.6013 0.1736 0.8238 0.6903 0.4683 0.0435 0.2153 0.3781
Columns 20 through 25
0.8224 0.5720 0.2752 0.6638 0.9715 0.0297
0.9909 0.0442 0.9355 0.4878 0.3770 0.2785
0.5501 0.1578 0.6124 0.7138 0.7429 0.3901
0.3613 0.4253 0.2086 0.1753 0.7646 0.7250
0.3425 0.8539 0.1077 0.4708 0.4340 0.3933
0.0740 0.8235 0.1572 0.2822 0.3274 0.6290
0.4443 0.7000 0.9827 0.4097 0.2692 0.1893
0.0337 0.2448 0.6822 0.9138 0.1172 0.7882
0.3764 0.1029 0.6114 0.0423 0.9861 0.8363
0.3374 0.2396 0.0657 0.8695 0.4397 0.3174
(:,:,6) =
Columns 1 through 19
0.0033 0.2927 0.4264 0.1332 0.2415 0.7295 0.9767 0.9107 0.1318 0.7118 0.9255 0.6909 0.4158 0.2962 0.7614 0.8419 0.1654 0.4302 0.0222
0.1678 0.4385 0.4717 0.4377 0.0106 0.5105 0.3614 0.6143 0.7640 0.8465 0.8773 0.4293 0.6849 0.2809 0.3280 0.1068 0.2722 0.2647 0.3641
0.6661 0.8665 0.8876 0.7462 0.0204 0.5359 0.8440 0.4746 0.5335 0.3952 0.7718 0.3380 0.0489 0.8560 0.7551 0.1411 0.5408 0.4414 0.0513
0.7851 0.9598 0.5317 0.9935 0.3177 0.3204 0.1051 0.8214 0.3956 0.1964 0.0831 0.2789 0.0179 0.6262 0.8167 0.3241 0.2109 0.7512 0.1503
0.3303 0.7820 0.7344 0.4992 0.7589 0.0027 0.0980 0.0290 0.3765 0.0310 0.8001 0.7793 0.5528 0.4243 0.4869 0.9964 0.0846 0.2339 0.6096
0.5364 0.9495 0.8766 0.1682 0.5318 0.6930 0.7368 0.3657 0.7719 0.1206 0.0464 0.1892 0.8462 0.6369 0.9851 0.5386 0.4330 0.4899 0.2925
0.4017 0.1995 0.4424 0.5875 0.8294 0.6023 0.9826 0.5895 0.4044 0.6841 0.8209 0.3883 0.0739 0.0371 0.8075 0.4756 0.8898 0.5960 0.0507
0.0410 0.4026 0.0419 0.3005 0.2005 0.7721 0.1879 0.2124 0.6136 0.5076 0.1983 0.1037 0.2933 0.7815 0.2867 0.6074 0.0632 0.8178 0.9912
0.2756 0.6467 0.7691 0.9012 0.1762 0.0809 0.2578 0.1787 0.9215 0.9610 0.9895 0.7791 0.6516 0.1358 0.7782 0.7617 0.0669 0.1958 0.1749
0.3921 0.7081 0.0927 0.6641 0.8973 0.8553 0.3136 0.3753 0.0828 0.3849 0.4778 0.2705 0.3805 0.5815 0.8126 0.0539 0.0552 0.0603 0.1992
Columns 20 through 25
0.1194 0.4118 0.8931 0.6330 0.7192 0.4322
0.5543 0.1652 0.7239 0.3740 0.8143 0.3968
0.8026 1.0000 0.0751 0.5718 0.8551 0.5188
0.8854 0.9613 0.2702 0.2072 0.3297 0.1601
0.4706 0.6881 0.8045 0.1918 0.5795 0.3290
0.3641 0.7586 0.9642 0.9607 0.5449 0.2362
0.0921 0.1475 0.1726 0.9654 0.9958 0.4072
0.7856 0.1898 0.9194 0.8009 0.5920 0.4843
0.5044 0.0657 0.3261 0.2607 0.5235 0.2774
0.8039 0.2940 0.6013 0.1736 0.8238 0.6903
(:,:,7) =
Columns 1 through 19
0.2011 0.2726 0.9072 0.1600 0.8224 0.5720 0.2752 0.6638 0.9715 0.0297 0.0033 0.2927 0.4264 0.1332 0.2415 0.7295 0.9767 0.9107 0.1318
0.7299 0.7016 0.2639 0.0332 0.9909 0.0442 0.9355 0.4878 0.3770 0.2785 0.1678 0.4385 0.4717 0.4377 0.0106 0.5105 0.3614 0.6143 0.7640
0.3871 0.0247 0.1508 0.5312 0.5501 0.1578 0.6124 0.7138 0.7429 0.3901 0.6661 0.8665 0.8876 0.7462 0.0204 0.5359 0.8440 0.4746 0.5335
0.5885 0.8163 0.7043 0.2722 0.3613 0.4253 0.2086 0.1753 0.7646 0.7250 0.7851 0.9598 0.5317 0.9935 0.3177 0.3204 0.1051 0.8214 0.3956
0.7296 0.9661 0.8417 0.4322 0.3425 0.8539 0.1077 0.4708 0.4340 0.3933 0.3303 0.7820 0.7344 0.4992 0.7589 0.0027 0.0980 0.0290 0.3765
0.3217 0.0573 0.5500 0.5746 0.0740 0.8235 0.1572 0.2822 0.3274 0.6290 0.5364 0.9495 0.8766 0.1682 0.5318 0.6930 0.7368 0.3657 0.7719
0.4900 0.9518 0.4734 0.7550 0.4443 0.7000 0.9827 0.4097 0.2692 0.1893 0.4017 0.1995 0.4424 0.5875 0.8294 0.6023 0.9826 0.5895 0.4044
0.8502 0.5559 0.3164 0.8014 0.0337 0.2448 0.6822 0.9138 0.1172 0.7882 0.0410 0.4026 0.0419 0.3005 0.2005 0.7721 0.1879 0.2124 0.6136
0.3124 0.7538 0.7401 0.2160 0.3764 0.1029 0.6114 0.0423 0.9861 0.8363 0.2756 0.6467 0.7691 0.9012 0.1762 0.0809 0.2578 0.1787 0.9215
0.4683 0.0435 0.2153 0.3781 0.3374 0.2396 0.0657 0.8695 0.4397 0.3174 0.3921 0.7081 0.0927 0.6641 0.8973 0.8553 0.3136 0.3753 0.0828
Columns 20 through 25
0.7118 0.9255 0.6909 0.4158 0.2962 0.7614
0.8465 0.8773 0.4293 0.6849 0.2809 0.3280
0.3952 0.7718 0.3380 0.0489 0.8560 0.7551
0.1964 0.0831 0.2789 0.0179 0.6262 0.8167
0.0310 0.8001 0.7793 0.5528 0.4243 0.4869
0.1206 0.0464 0.1892 0.8462 0.6369 0.9851
0.6841 0.8209 0.3883 0.0739 0.0371 0.8075
0.5076 0.1983 0.1037 0.2933 0.7815 0.2867
0.9610 0.9895 0.7791 0.6516 0.1358 0.7782
0.3849 0.4778 0.2705 0.3805 0.5815 0.8126