error using horzcat function

Question

rida 2023-6-14

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https://ww2.mathworks.cn/matlabcentral/answers/1982809-error-using-horzcat-function

评论： rida 2023-6-14

Very simple code of adding two matrices horizontally retyrns an error using horzcat, dimensions of arrays being concatenated are not consistent. the error is on line (theta = [theta(:,1:6),zeros(length(theta),1)];).

the excel file has a matrix of 4x6, which i check with size theta even.

the code is:

clear all

clc

% Input:

tmp = importdata ('exp.xlsx');

theta = tmp.data;

theta = [theta(:,1:6),zeros(length(theta),1)];

% Calcu

theta (:,7) = theta (:,2).*theta(:,3);

%output

file_name = 'total.txt';

fid = fopen(file_name,'w');

fprintf(fid,'This file is written by matlab code.\n\n');

fprintf(fid,'This code will calculate the total.\n\n');

for i = 1:length(theta)

fprintf(fid,'The total of %d with age %f and exp %f is %f.\n',theta(i,1),theta(i,2),theta(i,3),theta(i,4));

end

fprintf(fid,'\nENDFILE');

fclose (fid);

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Answer 1

VBBV 2023-6-14

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https://ww2.mathworks.cn/matlabcentral/answers/1982809-error-using-horzcat-function#answer_1255409

编辑：VBBV 2023-6-14

在 MATLAB Online 中打开

theta = [theta(:,1:6),zeros(size(theta,1),1)];

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Steven Lord 2023-6-14

在 MATLAB Online 中打开

The length function on a non-empty array returns the size in the longest dimension of your array. That's not necessarily the number of rows.

A = ones(3, 6);
length(A)
ans = 6

Calling size with 1 as the dimension input will give you the number of rows in the array.

size(A, 1)
ans = 3

rida 2023-6-14

thanks, this was very helpful. much thanks

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Answer 2

Satwik 2023-6-14

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You can make the following change if your goal is to concatenate.

tmp = zeros(4,6);
theta = tmp;
theta = [theta(:,1:6),zeros(size(theta,1),1)]
theta = 4×7
     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