Remove empty rows from matrix
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Hi folks,
I have the following matrix:
0.6857 0.1248 0.9636 1.0884 0.4807 0.6077 0.3644 0 0 0
0.9093 1.0006 1.0006 1.0006 1.0006 0.3702 0 0 0 0
0.6367 1.0106 0.5669 0.4437 1.0106 1.0106 0.4608 0 0 0
0.2100 0.3250 1.1000 0.9750 0.1250 1.1000 0.4070 0 0 0
0.2048 0.4401 0.7116 1.1518 0.1521 0.2741 0 0 0 0
0.5575 0.2119 1.2212 0.3091 0.9121 0.8300 0.0993 0 0 0
0.6041 1.0239 0.6050 0.4189 1.0239 0.3428 0 0 0 0
0.5817 1.0205 0.4559 0.5645 1.0205 0.3417 0 0 0 0
0.9277 1.0209 0.5690 0.4519 1.0209 1.0209 0.4390 0 0 0
0.1817 1.0217 0.7974 0.2243 0.4393 0 0 0 0 0
0.4787 0.9174 0.2224 1.1398 0.7216 0.4182 0.3816 0 0 0
0.9091 1.0004 1.0004 1.0004 1.0004 0.5803 0 0 0 0
0.2126 1.0104 0.1849 1.1953 0.4451 0.2482 0 0 0 0
0.2531 0.2652 1.0657 1.0657 0.4962 0.5695 0.7034 0 0 0
0.2072 0.8844 0.2805 1.1650 0.5038 0.2651 0 0 0 0
0.3229 1.0774 0.0362 1.1136 1.1136 0.0092 0.3636 0 0 0
0.2172 1.2212 0.0671 1.1541 0.5882 0.2788 0 0 0 0
0.3084 1.0633 1.0633 0.3386 0.4706 0 0 0 0 0
0.2108 1.0037 1.0037 1.0037 0.3361 0 0 0 0 0
0.1521 0.0784 1.0078 1.0862 0.4669 0.6193 0.3637 0 0 0
0.9111 1.0026 1.0026 1.0026 1.0026 0.8622 0 0 0 0
0.1406 1.0046 1.0046 1.0046 1.0046 1.0046 1.0046 0.5075 0 0
0.1918 0.0487 1.0297 1.0784 0.5640 0.3634 0 0 0 0
0.1513 0.0229 1.2441 0.4140 0.8301 0.8509 0.0958 0 0 0
0.8749 1.0001 1.0001 0.0422 0 0 0 0 0 0
0.8900 1.0173 0.5089 0.5084 1.0173 1.0173 0.5565 0 0 0
0.8903 1.0177 0.7745 0 0 0 0 0 0 0
1.0498 0.0125 1.2351 0.4561 0.7790 0.4136 0 0 0 0
1.0150 0.7605 0.4198 0.8982 0 0 0 0 0 0
0.1808 1.0165 1.0165 1.0165 0.1931 0 0 0 0 0
0.8158 1.0071 0.2857 0.4807 0 0 0 0 0 0
0.8973 0.2251 0.9714 0.8502 0.3462 0.4006 0 0 0 0
0.2134 1.2000 0.1495 1.0506 0.7584 0.4417 0.3000 0 0 0
0.7503 1.0005 1.0005 1.0005 1.0005 0.5472 0 0 0 0
0.8519 1.1359 0.0001 0.8643 0 0 0 0 0 0
0.7315 0.4265 0.7546 0.3955 0 0 0 0 0 0
0.6675 0.8202 0 0 0 0 0 0 0 0
0.3814 1.0037 1.0037 1.0037 0.5490 0 0 0 0 0
0.3608 1.0934 0.0694 0.2967 0 0 0 0 0 0
0.1815 1.0204 1.0204 1.0204 1.0204 0.0804 0.6033 0 0 0
0.3523 1.0676 1.0676 0.0248 1.0429 0.5840 0 0 0 0
0.3721 0.6114 0.6717 0.4296 0 0 0 0 0 0
0.1866 1.0493 1.0493 0.5664 0.4830 1.0493 0.7450 0 0 0
0.2975 1.0260 0.0635 0.9624 1.0260 0.5612 0 0 0 0
0.3385 0.8884 0 0 0 0 0 0 0 0
0.2690 0.8727 0.3151 0.3977 0 0 0 0 0 0
0.2374 1.0482 0.7679 0.2802 1.0482 0.5733 0 0 0 0
0.1428 1.0986 0.2470 0.1208 0 0 0 0 0 0
0.1407 1.0821 1.0821 0.1822 0.8999 0.5919 0 0 0 0
0.1300 0.7610 0 0 0 0 0 0 0 0
0.9675 0.0053 0.4343 0 0 0 0 0 0 0
0.1817 1.0220 1.0220 1.0220 0.9418 0.0802 1.0220 0.2555 0 0
0.8054 1.0738 0.0971 0.9767 0.5874 0 0 0 0 0
0.7961 0.2463 0.5288 0 0 0 0 0 0 0
0.6895 0.6923 0.3524 1.0447 0.5715 0 0 0 0 0
0.6871 0 0 0 0 0 0 0 0 0
0.9155 0 0 0 0 0 0 0 0 0
0.4147 0 0 0 0 0 0 0 0 0
0.7308 0.0113 1.1596 0.8044 0.3522 0 0 0 0 0
0.6601 0.3453 0 0 0 0 0 0 0 0
0.5076 0.0782 0 0 0 0 0 0 0 0
0.7649 0.2744 0.5651 0 0 0 0 0 0 0
0.6115 0.3237 0.1214 0 0 0 0 0 0 0
0.7236 0.0776 0.6387 0 0 0 0 0 0 0
0.5311 0.1151 0.9963 0 0 0 0 0 0 0
0.1641 0.0599 0.9660 1.0259 0.5612 0 0 0 0 0
0.8965 0 0 0 0 0 0 0 0 0
0.6188 1.0043 0.1607 0 0 0 0 0 0 0
0.4533 0.3284 0.9263 0 0 0 0 0 0 0
0.3628 0.4568 0.4365 0 0 0 0 0 0 0
0.2558 0.5884 0 0 0 0 0 0 0 0
0.1884 0.4902 0 0 0 0 0 0 0 0
0.1455 0.0447 0.5526 0 0 0 0 0 0 0
0.0793 0.3838 0 0 0 0 0 0 0 0
0.0805 1.0149 0.6064 0 0 0 0 0 0 0
0.7523 0.8290 0.2982 1.1272 0.5694 0 0 0 0 0
0.1034 0.9373 0.3661 1.1931 0.1102 0.7427 0 0 0 0
0.0888 0.4431 0.6763 0.0638 0 0 0 0 0 0
0.0670 0.3839 0 0 0 0 0 0 0 0
0.0681 1.0164 0.6073 0 0 0 0 0 0 0
0.0755 0.4427 0.6843 0.0642 0 0 0 0 0 0
0.5619 0.4598 0.6869 1.1467 0.2045 0 0 0 0 0
0.4987 0.3906 0 0 0 0 0 0 0 0
0.5430 0.0114 1.0968 0.0632 0 0 0 0 0 0
0.4407 0.4027 0 0 0 0 0 0 0 0
0.4495 1.0963 0.2350 0.8613 0.5538 0 0 0 0 0
0.5038 0.4028 0 0 0 0 0 0 0 0
0.4943 0.0541 1.1424 0.0651 0 0 0 0 0 0
0.6954 0.4171 0 0 0 0 0 0 0 0
0.4677 0.2769 1.1634 0.0663 0 0 0 0 0 0
0.1589 1.1350 0.2493 0.8856 0.5733 0 0 0 0 0
0.3814 0.0163 1.2831 0.0731 0 0 0 0 0 0
0.6389 1.0369 0.4251 0 0 0 0 0 0 0
0.0710 1.0149 0.5551 0 0 0 0 0 0 0
0.4376 0.6881 1.0147 0 0 0 0 0 0 0
0.6393 1.1416 0.2036 0 0 0 0 0 0 0
0.3888 1.0800 0.1926 0 0 0 0 0 0 0
0.6852 0.3812 0 0 0 0 0 0 0 0
0.4217 0.7882 0.3831 0.6674 0 0 0 0 0 0
0.2469 1.0330 0.1550 0.2272 0 0 0 0 0 0
0.6003 0.1677 0.6004 0 0 0 0 0 0 0
0.3019 0.1893 1.0737 0.5634 0.0933 0 0 0 0 0
0.8692 0.1094 0.5962 0 0 0 0 0 0 0
0.3294 0.5862 0.7919 0.6614 0.0828 0 0 0 0 0
0.3616 1.1205 0.0095 0.5708 0 0 0 0 0 0
0.9761 0.2160 0.9891 0.4625 0 0 0 0 0 0
0.1902 1.0011 0.5057 0 0 0 0 0 0 0
0.2418 1.0338 1.0338 0.5295 0 0 0 0 0 0
0.2351 1.0051 0.1556 0.8495 0.4699 0 0 0 0 0
0.2517 1.0759 1.0233 0.0526 0.5968 0 0 0 0 0
0.2342 1.0014 1.0014 0.4238 0 0 0 0 0 0
0.2430 1.0389 0.9815 0.0574 0.4320 0 0 0 0 0
0.2707 0.5728 0.5845 1.1573 0.2449 0.2636 0 0 0 0
0.1065 0.1941 1.2852 0.1126 1.1726 0.4194 0.2113 0 0 0
0.5830 0.5932 0 0 0 0 0 0 0 0
0.4807 0.7002 0.5100 1.2102 0.0551 0.4094 0 0 0 0
0.8563 0.0122 0.5702 0 0 0 0 0 0 0
0.1487 0.9660 0.3856 0.3652 0 0 0 0 0 0
0.7246 0.1034 0.4980 0 0 0 0 0 0 0
0.2777 0.7889 0.3046 0 0 0 0 0 0 0
Columns 11 through 20
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
I want to remove all the rows which are all zeros.
Thanks
1 Comment
Stephen23
on 17 Sep 2018
None of the rows are all zeros.
Accepted Answer
Star Strider
on 17 Sep 2018
If ‘M’ is your matrix, this works:
M = M(~all(M == 0, 2),:);
It will remove the ‘all zero’ rows using ‘logical indexing’.
4 Comments
Harry Saner
on 28 Mar 2020
This was really helpful thanks!
what does the 2 do or mean? I can see that it's basically saying for M the rows of the matrix M "not all" the elements that are equal to 0 must be removed
but how would you explain each part of that line of code in words?
Star Strider
on 29 Mar 2020
My pleasure!
The code assigns to ‘M’ the rows of the original ‘M’ that do not have all the elements of each row equal to 0.
It has the effect of elimiinating the rows in which all the elements of the row are equal to 0. The ‘2’ dimension argument to the all function tells the all function to look along the rows (rather than the columns, that would be the default dimension 1). The first part of the code:
~all(M == 0, 2)
creates the logical row index, and the code assigna all the columns in the original matrix (using the wildcard ‘:’) where the row argument logical index is true, or logical 1.
Thiago de Aquino Costa Sousa
on 23 Nov 2022
And what if, instead of 0 I have empty [] cells??? How can I remove them?
@Thiago de Aquino Costa Sousa: If you have a cell array (not a matrix as in the question) and you want to remove those rows whose elements all contain the empty array [], then you can do this:
% a cell array with some cells containing empty arrays []:
C = {1 [] 3; [] [] []; [7 8] [] []}
C = C(~all(cellfun(@isempty,C),2),:)
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