How to add rows containing zeros to a matrix

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Dr Sohaib Khan
Dr Sohaib Khan 2023-7-27
评论： Dr Sohaib Khan 2023-7-28
I have a "2x101" matrix, I want to add 4 rows to it, containing "zeros" to make it "6x101" matrix.
Please if anyone could guide me on syntax. Thankyou.

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采纳的回答

Cris LaPierre
Cris LaPierre 2023-7-27
Ran in:
A = rand(2,6)
A = 2×6
0.8131 0.2963 0.1224 0.8259 0.2399 0.5947 0.7303 0.1732 0.9839 0.2746 0.6453 0.7036
A(3:4,:)=0
A = 4×6
0.8131 0.2963 0.1224 0.8259 0.2399 0.5947 0.7303 0.1732 0.9839 0.2746 0.6453 0.7036 0 0 0 0 0 0 0 0 0 0 0 0

更多回答（3 个）

Voss
Voss 2023-7-28
Ran in:
Here's one way:
% a 2x101 matrix
a = rand(2,101)
a = 2×101
0.2749 0.6630 0.7375 0.2538 0.1755 0.5986 0.1725 0.4662 0.3609 0.7840 0.8763 0.3446 0.3603 0.8626 0.2283 0.1468 0.3254 0.3290 0.3960 0.4185 0.1099 0.0486 0.0626 0.7403 0.6850 0.4095 0.8703 0.1152 0.5754 0.7633 0.8014 0.8300 0.6248 0.5979 0.5868 0.4567 0.0246 0.0519 0.1590 0.1996 0.5126 0.0511 0.1397 0.9698 0.5512 0.3256 0.6557 0.6494 0.0743 0.7528 0.8313 0.6114 0.4597 0.6038 0.5030 0.9302 0.4747 0.8711 0.4699 0.2633
% append 4 rows of zeros
a = [a; zeros(4,size(a,2))]
a = 6×101
0.2749 0.6630 0.7375 0.2538 0.1755 0.5986 0.1725 0.4662 0.3609 0.7840 0.8763 0.3446 0.3603 0.8626 0.2283 0.1468 0.3254 0.3290 0.3960 0.4185 0.1099 0.0486 0.0626 0.7403 0.6850 0.4095 0.8703 0.1152 0.5754 0.7633 0.8014 0.8300 0.6248 0.5979 0.5868 0.4567 0.0246 0.0519 0.1590 0.1996 0.5126 0.0511 0.1397 0.9698 0.5512 0.3256 0.6557 0.6494 0.0743 0.7528 0.8313 0.6114 0.4597 0.6038 0.5030 0.9302 0.4747 0.8711 0.4699 0.2633 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 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 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 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
Les Beckham
Les Beckham 2023-7-27
Ran in:
Here is another way.
A = rand(2,6)
A = 2×6
0.5677 0.5655 0.2207 0.5221 0.5033 0.0094 0.1184 0.9091 0.7727 0.4403 0.6020 0.3454
A(4,6) = 0
A = 4×6
0.5677 0.5655 0.2207 0.5221 0.5033 0.0094 0.1184 0.9091 0.7727 0.4403 0.6020 0.3454 0 0 0 0 0 0 0 0 0 0 0 0
James Tursa
James Tursa 2023-7-27
编辑：James Tursa 2023-7-27
Ran in:
E.g., one way using the end syntax:
my_matrix = reshape(1:12,3,4)
my_matrix = 3×4
1 4 7 10 2 5 8 11 3 6 9 12
n = 4; % number of rows to append
my_matrix(end+n,1) = 0
my_matrix = 7×4
1 4 7 10 2 5 8 11 3 6 9 12 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Basically, setting any element in the 4th row beyond the current last row will cause MATLAB to append 4 rows of 0's to the matrix and set the particular element. I.e., MATLAB will dynamically increase the size of the matrix to accomodate the element you are trying to set, and all of the elements you don't set in the process are automatically set to 0's. In the above example, I set the (7,1) element to 0 explicitly, and MATLAB filled in all the other elements in the newly created four rows to 0's automatically.

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