dot-process_code_by function

Process code_by

Handles the code_by parameter and checks to make sure whether we can safely drop trends or not. Also handles any usage of I()

.process_code_by(formula, params, env, verbose)

Arguments

• formula: Formula used to set contrast
• params: Parameter list
• env: Not used
• verbose: Whether to throw the warning about invalid - usage

Returns

Modified parameter list with updated code_by