error using horzcat function

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);

 采纳的回答

VBBV
VBBV 2023-6-14
编辑:VBBV 2023-6-14
theta = [theta(:,1:6),zeros(size(theta,1),1)];

4 个评论

Preallocate the matrix theta with correct number of zeros
THANKS, ERROR RESOLVED. what exactly happened here? it worked when i only had 3 columns
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
thanks, this was very helpful. much thanks

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更多回答(1 个)

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

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