How to select certain rows from a data set

I have a large data set with a data point for every day of the year. I have the first column giving the day of the year (1 to 365) and the 2nd column specifying the day of the week (1 is Sunday, 2 is Monday, etc.) and the 3rd column is the data. I want to analyze the data using only Mondays, Wednesdays and Fridays, aka rows where the 2nd column is 2, 4, or 6. How can I do this?

Answer 1

[Walter Roberson]

mask = ismember(YourData(:,2), [2, 4, 6]);
selected_data = YourData(mask, :);