此日期转换器需要一个常规字符串,在Py3中为unicode。但是loadtxt
将文本加载为字节串:
In [12]: mdates.strpdate2num('%Y-%m-%d')(b'1999-01-31')
---------------------------------------------------------------------------
....
TypeError: strptime() argument 0 must be str, not <class 'bytes'>
In [13]: fn = lambda astr: mdates.strpdate2num('%Y-%m-%d')(astr.decode())
In [14]: fn(b'1999-01-01')
Out[14]: 729755.0
在loadtxt中测试:
In [15]: txt=b"""1999-01-01
...: 2000-03-03
...: 2015-12-12
...: """
In [16]: np.loadtxt(txt.splitlines(), converters={0:fn})
Out[16]: array([ 729755., 730182., 735944.])