def read_float_array(filename, skipline=0):
    """
    Read an array of floats into an a list-of-lists.  Skip skipline
    lines from the start of the file.  Don't convert to a numpy array
    - to allow for varying numbers of entries per line.
    """
    a = open('data_raw2.txt', 'r').readlines()[skipline:]
    return [[float(j) for j in i.split()] for i in a]