Concept of the null operator question
조회 수: 5(최근 30일)
This is more of a conceputal question that I need help with.
If I have say sampleMatrix=[1,2,3,4,5] and then I type the code sampleMatrix(3)=, does that make the matrix now look like [1,2,4,5]?
I ask because I want to know if you do the previously mentioned null operator code, does that now make the third element 4, or is 4 still the fourth element?
Thank you and I apologize if it is confusing.
John D'Errico 2021년 3월 8일
편집: John D'Errico 2021년 3월 8일
MATLAB does not allow arrays with empty elements. Double precision arrays are always nice rectangular things. So, for example, the array
[1 2 3  5 6]
is just a vector with 5 elements. The 4th element there is the number 5.
Similarly, you cannot insert an "empty" cell into a vector.
Therefore, the syntax in MATLAB to delete an element of a vector is to set it equal to , empty brackets.
V = 1:5;
V(4) = 
Again, the result is a vector of length 4. Everything to the right of that element gets shuffled over.
You can use  to delete multiple elements at once, thus
V = 1:10;
V(2:2:end) = 
And, for example, the third element of the new vector V is just 5.
All of that said, you need to be careful when working with cell arrays, because cell arrays CAN contain empty cells. But for regular flat arrays,  is just the tool to delete elements.