how to make a sub matrix from specific indices

4 次查看（过去 30 天）
Kellie
Kellie 2023-4-14
评论： Walter Roberson 2023-4-14
I have a 1400x1400 matrix (A), from this I want to make a 10x10 submatrix but I want it at the followign indices:
312
323
673
876
1031
1326
1344
1354
1359
1384
is this possible?
Thank you!

请先登录，再回答此问题。

回答（1 个）

Walter Roberson
Walter Roberson 2023-4-14
编辑：Walter Roberson 2023-4-14
sizeA = [1400 1400];
indices = [312
323
673
876
1031
1326
1344
1354
1359
1384];
[r, c] = ind2sub(sizeA, indices);
nummat = size(r,1);
mats = cell(nummat,1);
for K = 1 : nummat
mats{K} = A(r(K):r(K)+9, c(K):c(K)+9);
end
Yes, it would be possible to vectorize this a bit, but the code would be notably more difficult to understand.
  2 个评论
VBBV
VBBV 2023-4-14
编辑：VBBV 2023-4-14
Ran in:
Both ind2sub & sub2ind are able to produce the 10 x10 matrix format, but which one is correct here is confusing for me,
sizeA = [1400 1400];
A = randn(1400);
indices = [312
323
673
876
1031
1326
1344
1354
1359
1384];
[r c] = ind2sub(sizeA, indices);
nummat = size(r,1);
mats = cell(nummat,1);
for K = 1 : nummat
mats{K} = A(r(K):r(K)+9, c(K):c(K)+9);
end
mats{:}
ans = 10×10
1.2274 0.3295 0.7968 1.4923 -0.7608 0.7907 -0.5803 0.2214 1.2191 -0.2977 0.4435 -1.4633 -0.7854 1.7629 -1.2268 0.8160 -1.0832 -0.9987 -0.4603 0.6937 -0.9401 -0.6759 0.8486 -1.0199 2.0416 -0.3673 -0.3748 0.1962 -0.6763 -2.5935 -0.5716 0.4462 1.7819 -0.1581 1.6739 0.0326 0.4167 0.5241 -1.1618 0.8784 -0.8986 -0.6070 0.0067 1.1046 1.2513 -1.4109 -0.9435 0.8504 1.7319 1.0161 -0.2454 -2.1883 -0.1573 1.0006 -0.7103 0.1212 -0.4622 -0.1738 0.3173 -0.1019 0.7547 -0.5365 -0.9112 -2.0777 0.3595 -0.6276 -0.2749 -0.3126 1.2341 0.4672 0.1448 -0.5764 -0.2750 0.2195 1.0517 0.3727 -0.3154 0.7365 0.2040 0.1246 0.5426 -0.1619 0.0019 2.6920 1.1146 0.1145 -0.0051 0.9233 0.4249 1.4796 -0.6364 0.6818 -1.7166 -1.4217 -1.6261 1.8180 -1.3637 0.8519 -0.3774 -0.7804
ans = 10×10
0.6697 -0.2216 0.6877 -1.8931 -0.0014 -0.6697 0.0405 -0.1257 -1.5222 -0.4424 -0.4472 -0.6073 0.4856 -0.2113 -0.0960 0.9896 0.3959 0.1211 -0.7276 0.2936 -0.2850 0.6803 0.3817 1.4337 -1.0523 -0.0551 1.5178 0.9039 1.3457 0.9360 -0.8927 -0.5396 -0.3796 -0.7903 -0.7854 -1.6147 0.3620 0.6523 -1.1203 0.2483 -0.7449 -0.9152 -0.7908 -0.0733 0.5327 -1.7781 1.4260 -0.2516 -1.0976 0.4227 -1.2642 0.1351 0.0347 0.0540 -0.2795 0.6524 -1.9098 1.3335 -1.2926 -0.9181 0.9319 -1.0401 -0.7477 -1.7887 -1.5969 0.5209 0.4045 1.5619 -0.1162 1.7773 0.0869 -0.5220 1.1894 -1.3465 1.5531 0.0609 0.7463 1.0551 -0.0238 -0.1360 -1.2583 0.6302 0.2016 0.3634 0.2360 -0.6430 0.9249 0.7618 0.0457 -0.7809 1.3842 0.3534 -0.0488 1.4713 -0.4480 -1.7879 0.3722 0.8602 -0.3932 0.2565
ans = 10×10
-2.4064 0.5570 -0.8339 -2.4067 1.3686 0.6052 1.7021 -0.0917 0.7401 -0.5899 1.7309 0.0620 1.1621 -0.6396 0.0083 -0.0413 -1.4599 1.4072 -0.9151 -0.0624 -2.1788 -0.1313 0.4904 0.4537 -0.8098 1.0716 -0.6214 -1.2674 1.1373 0.3682 2.3037 0.1686 0.6020 0.7145 -0.5152 -1.0540 0.6063 0.1481 0.6786 -0.7383 1.0603 1.0721 0.5414 -0.2556 -1.2218 -0.2641 -1.7006 -0.9535 1.1841 1.3660 1.1520 0.7860 -0.9208 -0.3916 -0.1032 0.3456 2.0979 -0.1338 -0.5450 -0.3687 -1.6381 0.6963 -1.3700 1.1938 0.3811 -0.5439 1.5586 0.3399 -0.3875 -0.5935 -0.4899 -1.1105 -0.7849 0.5704 0.8833 0.9133 0.8279 0.8836 0.6648 2.0661 0.8146 0.1991 -0.1595 -0.6342 0.1025 0.6582 -0.6770 -1.0532 0.3205 -1.6026 -1.1088 -0.1052 0.8062 -0.1685 -0.9004 0.0265 0.0214 -1.6802 -0.6561 -1.5523
ans = 10×10
1.1268 0.0370 1.2579 -0.6739 -0.4390 -0.4109 0.7583 -0.8408 2.2990 -0.8014 0.1990 0.8289 1.8590 -0.8605 -0.3906 1.5655 1.2351 -0.6535 -1.1849 -0.3863 -0.7625 -2.2754 0.7528 0.3255 -0.8675 0.4560 2.4472 0.8346 0.6872 -0.4408 -0.3979 0.8189 -0.6469 -0.2538 -0.7524 -1.1820 0.4280 1.4433 0.2509 -1.2179 -0.5213 -0.9014 -0.8947 0.4506 0.6618 1.4883 0.0988 0.8976 1.0143 -0.3166 1.2459 0.5731 -0.0862 0.0879 -0.1629 0.0623 1.2049 0.1768 -0.0708 -1.4698 -0.7387 -1.1931 0.7336 -0.9635 0.7394 -1.2931 0.5884 1.0487 -1.6886 0.7649 -0.0832 -0.1566 1.1809 0.9180 0.2742 -0.9146 -0.6467 0.1735 1.1813 -0.9604 -0.1030 -1.3454 -0.9303 -0.5204 2.0201 1.6035 -0.4046 0.0663 0.4674 -1.2442 0.2572 -0.5886 1.2753 -0.7095 -1.3927 -1.5557 -0.4019 2.3746 -1.6129 0.8868
ans = 10×10
0.9847 -0.4020 -0.5251 0.1701 -0.6140 -0.6884 0.6534 -0.3032 0.3091 -0.3692 0.9861 -0.4543 1.5570 -0.2683 0.7104 0.3965 0.9716 -0.1630 -0.5840 0.0969 0.7748 -0.6726 1.0529 -2.1886 0.3496 0.2964 -1.0824 0.0658 0.2957 0.8040 -0.3948 0.1086 0.1299 -1.5286 -0.9352 0.8854 -0.2151 -0.9710 -0.0098 -0.3886 -0.9170 -0.4063 -1.2175 0.2642 0.3906 0.5182 0.9190 -0.1160 0.5534 -2.1486 0.0223 -1.6013 0.8343 -0.9097 1.8630 0.2969 0.5699 -0.4728 -1.7668 0.2987 -0.5719 -0.2976 0.1616 -1.2727 0.6519 -0.3377 -0.0481 0.1742 -0.4020 1.5383 1.9145 -0.2494 0.5216 -1.5958 -0.5605 0.1725 0.2519 1.8173 -0.7086 -0.4622 -0.4151 1.3074 -0.9092 -1.5118 -0.0560 -1.3397 2.1519 0.3999 1.3701 -0.5088 0.1468 -0.1830 -0.3500 -1.2348 -0.0941 -0.1012 1.2819 1.4033 -1.1342 -0.0837
ans = 10×10
0.0933 1.5828 0.4261 -0.4075 1.7207 0.3468 0.7990 0.5301 -2.3321 -0.2226 -0.1458 1.0198 -1.3263 0.4327 -0.2883 0.1084 -0.0221 -0.5067 0.7344 -0.3785 0.6271 -0.2777 -0.2144 1.5244 0.0726 -0.9391 -0.5420 1.5376 -2.1879 1.7058 1.2357 2.7229 0.0155 -0.4603 0.5415 -0.1820 0.1462 0.0159 1.7782 -0.6156 -1.6198 -0.6055 -0.3607 0.5433 -0.0195 -1.8119 0.2418 1.4614 -1.6690 0.2379 -1.3812 -1.1528 -0.7278 0.4328 1.0143 1.0823 -0.6154 1.0609 1.2193 -0.1190 0.0039 -0.9788 -0.0482 0.5554 1.0455 0.3008 -0.4074 -0.6076 0.8555 -0.4619 0.5751 0.4971 -0.5637 -1.4416 0.3489 -0.2736 -0.3581 2.1733 -1.0961 -1.3528 1.7314 -1.7163 -0.7950 0.8097 0.2180 -1.3015 1.1040 -0.4973 0.5934 -0.9828 1.0615 1.2497 -1.7331 0.1935 1.8003 0.3016 -0.9228 0.6502 1.1792 1.5103
ans = 10×10
-0.4503 0.8373 -0.8358 1.6776 1.0439 -1.4601 -0.4207 0.6244 -0.5346 0.3198 0.9552 -0.1955 -1.9583 -0.4792 0.0437 -0.0828 -0.5921 1.1775 -0.1669 0.2423 0.5675 -0.8013 1.5307 -1.1743 -0.1577 -0.2642 0.0203 -1.2842 0.9979 -0.4941 -0.4357 0.3852 0.9015 1.1771 0.1913 1.0853 -1.3117 1.2533 0.0945 1.4830 0.1810 -1.7190 -1.4033 -0.5826 -1.1408 -0.9292 -0.5815 -0.1439 -0.3964 0.4006 0.8684 0.7353 -1.3325 1.5264 -1.1969 -0.5514 -1.0830 0.1895 -2.2601 0.8543 1.9686 2.0115 0.2306 -1.0766 1.7776 -0.3819 1.4037 0.2358 0.0671 0.4554 -1.2876 0.4543 -2.1239 -0.4798 1.3068 -0.6482 -0.0127 -1.4443 -0.4105 0.8932 0.4975 -0.5648 1.7621 -0.3012 -0.8388 0.1537 0.3617 1.5525 0.0675 -1.4487 -0.4951 1.9292 1.7286 -0.1753 -1.1269 -0.9260 0.9436 0.5801 -1.1331 0.4536
ans = 10×10
1.1286 -1.3361 -1.4970 0.6643 -0.7034 0.5047 -0.5886 -0.1161 0.4318 1.5564 -0.5444 0.0786 0.1863 -1.0993 -1.7784 0.2960 -0.6002 -0.6993 -0.4482 1.1978 1.1724 -0.6675 0.9070 -1.5070 -0.0034 -0.5917 1.1190 -0.3524 -0.5115 -1.9743 0.6043 -0.7524 0.2611 0.2953 -0.2356 1.1350 2.1098 0.0302 -0.0072 0.1504 0.3063 0.3137 -0.5007 -0.5035 -0.2251 -0.4456 0.1703 0.0302 -2.4383 -0.5960 -0.3456 2.1602 -0.8945 0.6599 0.7097 0.0978 2.0203 -1.0533 0.7168 -0.3909 -0.4985 2.0481 0.8436 0.1718 0.5416 1.7352 0.8161 1.0455 -0.0929 1.2690 0.4820 0.0320 1.0301 -0.4336 0.5284 0.1875 2.2568 -0.4538 -0.1784 0.2202 -1.3458 0.5211 2.6368 0.6873 -1.4840 0.5279 -0.8495 -0.7011 1.2811 1.4801 0.7558 1.1309 0.3442 0.3185 1.8050 2.3447 -0.5398 1.3449 -0.8441 0.9285
ans = 10×10
-0.3456 2.1602 -0.8945 0.6599 0.7097 0.0978 2.0203 -1.0533 0.7168 -0.3909 -0.4985 2.0481 0.8436 0.1718 0.5416 1.7352 0.8161 1.0455 -0.0929 1.2690 0.4820 0.0320 1.0301 -0.4336 0.5284 0.1875 2.2568 -0.4538 -0.1784 0.2202 -1.3458 0.5211 2.6368 0.6873 -1.4840 0.5279 -0.8495 -0.7011 1.2811 1.4801 0.7558 1.1309 0.3442 0.3185 1.8050 2.3447 -0.5398 1.3449 -0.8441 0.9285 -0.3737 -0.7873 1.6613 0.4257 -0.7976 -0.0925 -1.0963 0.4607 2.2001 -0.6749 1.1886 -0.6613 1.1697 0.3777 -0.6765 0.5386 -0.3835 0.0877 -0.4095 1.2290 -0.8211 0.8848 0.7490 -0.5707 0.9414 -1.5440 -0.8125 -0.5192 0.8658 -0.8438 1.6599 0.7769 0.4541 -0.1691 0.7683 -1.9636 0.9507 0.8829 -1.5058 0.1840 -2.1856 0.2031 -0.3591 0.3669 -0.6781 0.5134 -0.5405 -0.4923 -1.0761 0.7079
ans = 10×10
-1.3066 0.1792 -0.3632 -0.2916 1.6796 1.3848 0.9249 -1.1241 0.8276 -0.6299 0.4465 -1.0432 -2.0024 -0.3961 0.2425 -1.3310 0.9709 0.6972 -1.3396 -1.4757 0.7585 0.0243 0.7183 1.3754 -0.7643 0.8189 2.5932 -0.3269 0.4465 0.9266 0.7364 0.4367 0.3985 -0.2891 -1.4749 -2.3235 -0.2126 2.1990 -0.1747 -0.4467 0.0126 0.3232 1.0698 0.5077 -1.4442 2.2230 0.4276 -1.5945 0.1920 -2.7698 0.8809 -0.1422 1.2161 1.8356 1.0401 -1.0258 -0.2862 -0.3394 0.2612 2.0778 -0.0869 -1.2442 -0.4470 -1.1189 -1.0614 -0.6622 0.9346 -1.3191 -0.1541 -0.4887 -1.7913 -0.5962 0.2035 -0.1535 1.2930 0.4868 1.2997 -1.0880 -0.0098 0.4224 0.9853 0.5005 -0.1731 0.9143 -0.8004 -1.7848 -0.9680 -1.8426 0.2232 1.3747 -1.1119 1.4142 -1.0316 -0.4480 -0.2625 0.1601 -1.4253 -1.2456 0.6185 0.7708
Walter Roberson
Walter Roberson 2023-4-14
Thanks for catching that, should be ind2sub()... I corrected my code.

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Loops and Conditional Statements 的更多信息

标签

产品


版本

R2022b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by