Dot indexing not supported

Hi,

I have the code:

x.y{2} = b

x is a 10by200 matrix and y is a row vector (1by200) and b is also a row vector (1by200) which has already been extracted.i want want to extract the columns or variables in y from which b corresponds to. when I run the code above Matlab says ‘dot indexing not supported for variables of this type’

Any ideas?

Thank you!

[JESUS DAVID ARIZA ROYETH]

Can you save your workspace using

save('variables')

and attach the variables.mat file here please?

Answer 1

[Walter Roberson]

You would only use

x.y

in one of the following cases:

1. x is a struct scalar that has a field named y . In this case, x.y would be a copy of the field y from the single x entry.
2. x is a struct array that has a field named y. In this case, x.y would be a "comma separated list" of all of the fields y from the x entries, in linear indexing order of x . This is not uncommon when extracting information from regionprops() results for example.
3. x is an object or object array with property named y
4. x is an object or object array with method named y

The only two cases in which assigning x.y{2} = b would be legal would be:

1. x is a scalar struct that has a field named y that is a cell array and the second entry of that cell array is being assigned to. However, the syntax does not work if x is a non-scalar struct array
2. x is a scalar object that has a property named y that is a cell array and the second entry of the property is being assigned to. However, the syntax does not work if x is a non-scalar object

You have indicated that x is a 10 by 200 matrix. Both of the matrix possibilities (x is struct array, x is object array) would generate comma-separated lists when you accessed the field or property y of the array, and using {} indexing of a comma separated list that has more than one entry is not valid.

I cannot tell what you are trying to do. I speculate that you must might possibly want something like

any( x(:,y) == b, 1)

but even that seems unlikely.