How do I call out a specific column in a matrix?

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jon
jon 2018-3-11
回答： CARLOS TOLOSA 2020-10-28
Hi all, I have a code in matlab which reads the data given to it(see attached), and here is my matlab code.
A = csvread('test1.txt');
B = A>1000;
C = A<1000;
Z1 = all(B(:,1:3)|(B(:,1:2)& B(:,4)),2);
Z2 = all(C(:,1:4),2);
X1 = all(B(:,1:3),2);
X2 = any(B(:,1:2),2);
C1 = {'','PowerGrip'};
C2 = {'','PrecisionGrip'};
C3 = {'','No Signal'};
[num2str(A),char(strcat({' '},C1(1+Z1),C2(1+X2),C3(1+Z2)))]
So what I want on Z1, is to set a condition, such that when rows of matrix from column 1 to 3 are greater than 1000, as well as when rows of matrix from columns 1, 2 and 4 are greater than 1000, there will be a display as shown in the outputs below. However, there seems to be some form of error with my Z1 and I cant seem to understand why. Is there a solution to this?
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Jan
Jan 2018-3-11
there seems to be some form of error with my Z1
Please post the error message or explain the difference between the results and your expectations. It is easier to solve a problem than to guess, what the problem is.

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回答（2 个）

Jan
Jan 2018-3-11
编辑：Jan 2018-3-11
With some guessing:
Z1 = all(B(:,1:3) | (B(:,1:2) & B(:,4)), 2);
In the part B(:,1:2) & B(:,4) you try to apply the and operator to a [n x 2] matrix and [n x 1] matrix. This cannot work, because the inputs must have the same size (or one can be a scalar). The same happens for the or operation also.
You want to achieve this:
rows of matrix from column 1 to 3 are greater than 1000, as well as when rows of
matrix from columns 1, 2 and 4 are greater than 1000
Isn't this the same as:
All elements of rows 1 to 4 are greater than 1000
? Rows 1:3 are greater than 1000 and rows [1,2,4] are greater than 1000 means: rows 1:4 are greater.
Z1 = all(B(:, 1:4), 2); % Or if B has 4 columns: all(B, 2)
Or maybe you want:
Z1 = all(B(:, 1:2), 2) & (B(:,3) | B(:,4));
  1 个评论
jon
jon 2018-3-11
编辑：jon 2018-3-11
Sorry for not mentioning, the cases I want are for Columns 1,2 and 3 > 1000, as well as Columns 1,2 and 4.. not for all columns 1 to 4..but I'm not sure how to make a case for 1,2 and 4?
EDIT: I have tried some of your suggestion and have tried using this line
Z1 = all(B(:,1:3),2 & (B(:,1:2)| B(:,4)));
and I got this
Error in Filereadtest (line 4)

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CARLOS TOLOSA
CARLOS TOLOSA 2020-10-28
Use indexing and counting. If G is matrix then G(i) is a particular entry of G. 'i' counts vertically so if G=[1 2;3 4] then G(2)=3. So to call a column of G from ith to jth row use G(i:j).
':' counts from i to j.

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