def grab_data(array, index):
    """
    This is a helper function for parsing position output.
    :param array: any array that's items are lists
    :param index: desired index of the sublists
    :return: subset: a list of all of the values at the given index in each sublist
    """
    subset = []
    for i in array:
        subset.append(float(i[index]))
    return subset