def set_binary_labels(input_examples, positive_label):
    """
    Replaces the class labels with 1.0 or -1.0, depending on whether 
    the class label matches 'positive_label'.
    Returns an array of tuples, where the first element is the label number 
    and the second is a path to the image file.
    """
    examples = []

    for example in input_examples:
        if example[0] == positive_label:
            examples.append(("1.0", example[1]))
        else:
            examples.append(("-1.0", example[1]))            
    return examples