Is there an 'Is___' Function that Checks if a Value is a [ ]?

Hello,

I know there are functions like istable, which checks if a given variable is a Table (1) or not a table (0).

Is there one that checks if a variable's value is a [ ]?

I'm not sure what it is called, but I have a script that takes in tables of a heater turning on or off.

Column A is time, and Column B is either a 1 for On or a 0 for Off.

In some cases that heater doesn't turn on, but if I don't catch it before I run the script, I get an error message.

There are a couple variables that get affected by this and give values with a [ ] in the workspace window.

I'd like to have a big if/else statement that says something like:

if variable is a [ ]
    disp('The heater does not turn off')
else
    %The rest of my code as normal
end

Let me know if this doesn't make sense, I can try to elaborate further.

Thanks.

Answer 1

[Voss]

isempty

[Jon]

Sweet thanks, must've missed that one while looking

Answer 2

[Walter Roberson]

isempty -- though isempty tests for any datatype that has a dimension of length 0 .

If you want to specifically test for [] then you should test isdouble(variable) && isequal(variable, [])

Note that if you have a table with a numeric variable, then the variable entry can never be [] -- the variable would have to be a cell array in order for an entry to be []

[Jon]

Cool thanks.

I think having it test for a zero dimension would still give me what I want, mainly that my one variable that looks for when the heater is on will give zero if the heater is never on.

[Walter Roberson]

Sounds like you are doing a find(). If so, then isempty() works well for that.

If it does happen to be a find() situation, then it turns out that there a number of situations in which it is more efficient to use logical indices instead of find(). Not always, though... sometimes find() is best.