arrays.py 文件源码

def decimate_custom(seq,cmp=None,pops=None,keeptime=3600*1.1):
    """ 
    @NOTE: Although faster, filter_array does a better decimation for trends
    It will remove all values from a list that doesn't provide information.
    In a set of X consecutive identical values it will remove all except 
    the first and the last.
    A custom compare method can be passed as argument
    :param seq: a list of (timestamp,value) values
    """
    if len(seq)<3: return seq
    if len(seq[0])<2: return seq
    import __builtin__
    cmp = cmp or __builtin__.cmp
    pops = pops if pops is not None else []
    while pops: pops.pop() 
    x0,x1,x2 = seq[0],seq[1],seq[2]

    for i in range(len(seq)-2):

        if not cmp(x0[1],seq[i+1][1]) and not cmp(seq[i+1][1],seq[i+2][1]):
            pops.append(i+1)
        else: 
            x0 = seq[i+1]

    for i in reversed(pops):
        seq.pop(i)
    return seq