A compact way to (i) sum two rows and two columns and then (ii) remove one of the two summed rows and one of the two summed columns

Question

Kymberly 2022-12-5

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1871332-a-compact-way-to-i-sum-two-rows-and-two-columns-and-then-ii-remove-one-of-the-two-summed-rows-an

评论： Kymberly 2022-12-5

A compact way to (i) get the sum of two rows and two columns and (ii) to then remove one of the summed rows and one of the summed columns, i.e. x3 in the example here below?

% Input 1:
x1 = [1 0 5 7 1 0
     3 2 0 1 2 0
     9 8 0 0 0 6
     5 5 6 7 1 1
     1 1 1 9 4 5
     0 0 1 7 6 2]
% Input 2:
% the rows to be summed are the 2nd and the 3rd, 
% while the columns to be summed are the 4th and the 5th.
x1 = 6×6
     1     0     5     7     1     0
     3     2     0     1     2     0
     9     8     0     0     0     6
     5     5     6     7     1     1
     1     1     1     9     4     5
     0     0     1     7     6     2
% For rows: (i) sum 2nd and 3rd rows and (ii) remove one of the two summed rows
x2 = vertcat(x1(1,:),x1(2,:)+x1(3,:),x1(4:6,:))
x2 = 5×6
     1     0     5     7     1     0
    12    10     0     1     2     6
     5     5     6     7     1     1
     1     1     1     9     4     5
     0     0     1     7     6     2
% For columns: (i) sum 4th and 5th columns and (ii) remove one of the two summed columns
% --> this is the desired output
x3 = [x2(:,1:3), x2(:,4)+x2(:,5), x2(:,6)] 
x3 = 5×5
     1     0     5     8     0
    12    10     0     3     6
     5     5     6     8     1
     1     1     1    13     5
     0     0     1    13     2

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Kymberly 2022-12-5

The same stuff, but just with the "Input 2" addded in a bit more sophisticated way:

% input 1
x1 = [1 0 5 7 1 0
     3 2 0 1 2 0
     9 8 0 0 0 6
     5 5 6 7 1 1
     1 1 1 9 4 5
     0 0 1 7 6 2]
x1 = 6×6
     1     0     5     7     1     0
     3     2     0     1     2     0
     9     8     0     0     0     6
     5     5     6     7     1     1
     1     1     1     9     4     5
     0     0     1     7     6     2
% input 2
r = 2;
c = 4;
% (i) sum 2nd and 3rd rows and (ii) remove one of the two summed rows
x2 = vertcat(x1(1:r-1,:),x1(r,:)+x1(r+1,:),x1(r+2:end,:))
x2 = 5×6
     1     0     5     7     1     0
    12    10     0     1     2     6
     5     5     6     7     1     1
     1     1     1     9     4     5
     0     0     1     7     6     2
% (i) sum 4th and 5th columns and (ii) remove one of the two summed columns
x3 = [x2(:,1:c-1), x2(:,c)+x2(:,c+1), x2(:,c+2:end)]
x3 = 5×5
     1     0     5     8     0
    12    10     0     3     6
     5     5     6     8     1
     1     1     1    13     5
     0     0     1    13     2

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Davide Masiello 2022-12-5

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1871332-a-compact-way-to-i-sum-two-rows-and-two-columns-and-then-ii-remove-one-of-the-two-summed-rows-an#answer_1120337

Your way is already quite compact. Maybe what you want to avoid is having to concatenate.

Then, you could try this.

x1 = [1 0 5 7 1 0
     3 2 0 1 2 0
     9 8 0 0 0 6
     5 5 6 7 1 1
     1 1 1 9 4 5
     0 0 1 7 6 2];
r = 2;
c = 4;
x1(r,:) = x1(r,:)+x1(r+1,:); x1(r+1,:) = []
x1 = 5×6
     1     0     5     7     1     0
    12    10     0     1     2     6
     5     5     6     7     1     1
     1     1     1     9     4     5
     0     0     1     7     6     2
x1(:,c) = x1(:,c)+x1(:,c+1); x1(:,c+1) = []
x1 = 5×5
     1     0     5     8     0
    12    10     0     3     6
     5     5     6     8     1
     1     1     1    13     5
     0     0     1    13     2