how can i prompt user to enter elements for specific row/columns

Question

Austin 2013-10-1

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https://ww2.mathworks.cn/matlabcentral/answers/88786-how-can-i-prompt-user-to-enter-elements-for-specific-row-columns

评论： Image Analyst 2021-1-18

script ive used:

m = input('Enter number of rows: ');
n = input('Enter number of columns: ');
for i = 1:m
  for j = 1:n
    str = ['Enter element in row ' num2str(i) ', col ' num2str(j) ': '];
    a(i,j) = input(str);
  end
end
a

but this script prompts the user for to enter all elements while i need only to prompt the user for specific rows and columns,can anyone kindly advise me on this?

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Answer 1

Image Analyst 2013-10-1

2
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https://ww2.mathworks.cn/matlabcentral/answers/88786-how-can-i-prompt-user-to-enter-elements-for-specific-row-columns#answer_98354

编辑：Image Analyst 2021-1-18

在 MATLAB Online 中打开

Let's say that you've stored the row, column combinations that need replacing in an array called rc. Then just do

numberOfElements = size(rc, 1);
for k = 1 : numberOfElements 
    row = rc(k, 1);
    column = rc(k, 2);
    str = sprintf('Enter the value to go into row %d, column %d : ', row, column);
    a(row, column) = input(str);
end
a

This will ask for only the table elements that you've specified in advance rather than all of them. For a little nicer program you should use inputdlg() instead of input().

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Walter Roberson 2021-1-18

在 MATLAB Online 中打开

The array rc is the array that describes which rows and columns you want to enter the values for. The first column of rc would be the row numbers, and the second column of rc would be the column numbers.

size(rc,1) represents the number of different locations that you want to prompt for. It would be less than or equal to the total number of elements in the matrix a . You could, for example, prompt to replace 5 elements out of a 75 x 43 array, and in that case size(rc,1) would be 5, the number of places you were going to replace.

m = 75;
n = 43;
a = zeros(m,n);
r = [randi(m, 5, 1), randi(n, 5, 1)];   %r now describes 5 random places to store into

Image Analyst 2021-1-18

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tbaracu:

Here is a full working demo:

a = ones(5, 14)
% Define which rows and columns need to be replaced.
rc = [
	1, 2;
	5, 12
	3, 8]
numberOfElements = size(rc, 1);
for k = 1 : numberOfElements
	row = rc(k, 1);
	column = rc(k, 2);
	str = sprintf('\nEnter the value to go into row %d, column %d : ', row, column);
	a(row, column) = input(str)
end