Plotting Two Consecutive Columns of Matrices

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Femi O. Jinadu 2021-12-21

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https://ww2.mathworks.cn/matlabcentral/answers/1615085-plotting-two-consecutive-columns-of-matrices

评论： Star Strider 2021-12-21

Hi,

I have 4 x 202 matrix, and I want to plot the columns in 2's e.g columns 1 and 2, next columns 3 and 4 as they represent X and Y coordinates. How can I do this?

Thanks

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Answer 1

Star Strider 2021-12-21

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https://ww2.mathworks.cn/matlabcentral/answers/1615085-plotting-two-consecutive-columns-of-matrices#answer_859305

在 MATLAB Online 中打开

First a (4 x 202) matrix defines a matrix of 4 rows and 202 columns. Assuming that it’s actually a (202 x 4) matrix, perhaps something like this —

M = randn(15, 4) % Prototype

M = 15×4

-1.4757 0.4730 -1.7963 0.5677 -1.4236 0.6301 -0.9039 -0.0171 -1.1303 1.3193 0.1080 0.2304 -1.2160 -0.9149 -0.3458 -1.0942 0.7360 0.9042 -0.1741 1.7954 0.1131 0.5694 1.0606 -0.2865 0.1741 -0.7245 -0.7010 1.2694 -1.8673 -0.5442 -0.6397 -2.0804 0.4837 0.0083 -0.6583 0.5971 -1.0150 -2.1755 0.5630 -0.2446

Mr = reshape(M, [], 2)

Mr = 30×2

-1.4757 -1.7963 -1.4236 -0.9039 -1.1303 0.1080 -1.2160 -0.3458 0.7360 -0.1741 0.1131 1.0606 0.1741 -0.7010 -1.8673 -0.6397 0.4837 -0.6583 -1.0150 0.5630

figure

plot(Mr(:,1), Mr(:,2), '.')

If the matrix actually is (4 x 202), transpose it first, then use the approach in this code example.

.

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Star Strider 2021-12-21

在 MATLAB Online 中打开

I am not certain what the matrix is (not supplied), nor am I certain what the desired result is.

See if this produces the desired result —

M = randn(4, 16) % Prototype Matrix (Random)

M = 4×16

0.0752 -0.2438 -1.1305 0.5674 -0.8264 -0.8058 -0.0557 0.5916 0.5528 -0.7535 0.6855 -0.0317 -0.5626 -1.2305 -1.7698 -0.1324 -0.7432 0.4237 -1.8701 -1.1656 -1.3737 0.9483 1.0826 0.8271 1.4154 0.2680 1.7482 -0.3266 -0.7582 2.0894 -0.4560 0.2552 1.5404 0.1558 -0.9183 -0.8252 0.9294 -1.2118 -0.2726 1.3016 -0.1283 0.1639 -0.1338 0.1248 -0.1141 1.1451 -0.5234 -0.6048 -0.6458 0.2220 0.9233 0.0739 0.8112 -0.6546 -0.4364 0.6713 0.8739 -0.2792 -0.1227 1.6188 1.1815 -0.2486 -0.1096 0.5278

figure

hold on

for k = 1:2:fix(size(M,2))/2

colpair = [1 2]+(k-1) % Check Indices

xvct = M(:,colpair(:,1)) % Check X-Vector

yvct = M(:,colpair(:,2)) % Check Y-Vector

plot(M(:,colpair(:,1)), M(:,colpair(:,2)), '.-')

end

colpair = 1×2

1 2

xvct = 4×1

0.0752 -0.7432 1.5404 -0.6458

yvct = 4×1

-0.2438 0.4237 0.1558 0.2220

colpair = 1×2

3 4

xvct = 4×1

-1.1305 -1.8701 -0.9183 0.9233

yvct = 4×1

0.5674 -1.1656 -0.8252 0.0739

colpair = 1×2

5 6

xvct = 4×1

-0.8264 -1.3737 0.9294 0.8112

yvct = 4×1

-0.8058 0.9483 -1.2118 -0.6546

colpair = 1×2

7 8

xvct = 4×1

-0.0557 1.0826 -0.2726 -0.4364

yvct = 4×1

0.5916 0.8271 1.3016 0.6713

hold off

This reports the results of each loop iteration as well as plots them, so check to be certain it references the appropriate matrix columns and produces the desired result (since I still have no idea what that is). First, use a subset of the maatrix, for example the first 16 columns as I did here (there must be an even number of columns). If that works, see if the entire matrix plots correctly.

.