How do I create dummy variables with if statements?

I have a dataset with excess return, R, which consists of 10 000 rows and 1 column.

I want to create a new variable X that takes the value of 1 for each row in R if R>0 for all rows in R. And it takes the value of 0 if R<0.

Probably a simple question, but couldnt find any other answers out there that worked for me.

Answer 1

[madhan ravi]

X = R > 0

[Walter Roberson]

X = nan(size(R));
X(R > 0) = 1;
X(R < 0) = 0;

The nan is needed because the user did not define the result for R == 0 exactly.

[madhan ravi]

Thank you sir Walter

[Tobias M]

Thank you! This worked.

[Tobias M]

Suppose I now have generated 10000 rows with random numbers ranging within (0,1). From the code you provided me with, I have generated 10000 rows with dummy variables.

Dummy value = 1 signifies a positive return, while 0= negative return. Suppose I have p=60% for predicting that return will be positive, and p=80% that return will be negative.

I have generated random numbers using c=rand(10000,1). If dummy variable is 1, and the value in c > 0.6, I have made a "wrong" prediction, c<0.6 signifies a correct prediction. How can i compute returns that take value of market return if i made correct prediction if dummy=1, and value of risk-free return if I made a wrong prediction, c>0.6, and vice versa if dummy=0?

[madhan ravi]

https://www.mathworks.com/matlabcentral/answers/638655-how-do-i-create-dummy-variables-with-if-statements#comment_1115050

So I won't "predict" anything.