Creating Dummy Variable without dummyvar

Hello everyone,

I am trying to create a month-level time dummy variable for a "double" variable called lnrent (I am unable to use the dummyvar command due to licensing issues)

I have therefore specified the following function:

function res = create_Dummies(x)
    %create dummy variables for a given vector of values
    levels = unique(x); 
    res = [];
    for i=levels
        res = [res, (x == i)'];
    end   
end 

Where X would be the variable "lnrent" for which the dummy should be created.

However, I keep getting the following error-message when I call it:

Error in create_Dummies (line 10)
        res = [res, (x == i)'];

saying that I should preallocate for speed.

How do I do this? I am an absolute beginner and very unsure. Any help would be appreciated!

(I apologise in advance for an community-conduct-errors)

Answer 1

[Matt J]

function res = create_Dummies(x)
    %create dummy variables for a given vector of values
    res=x(:)==unique(x)';
end 

[JoV]

Thank you so much! That worked perfectly