无法使用numpy的loadtxt如下至今转换与python3.6

Question

我的代码：

import numpy as np 
import matplotlib.dates as mdates 

stockFile = 'HistoricalQuotes.csv' 

dates, close = np.loadtxt(stockFile, delimiter=',', unpack=True, usecols=(0,1), \ 
          converters = {0: mdates.strpdate2num('%Y-%m-%d')}) 
print("Dates = ", dates) 

和回溯：

Traceback (most recent call last): 


File "/Users/zdlzdlxs/Documents/workspace/pynum_practice/part3/simplestats.py", line 7, in <module> 
    converters = {0: mdates.strpdate2num('%Y-%m-%d')}) 
    File "/Users/zdlzdlxs/Library/Python/3.6/lib/python/site-packages/numpy/lib/npyio.py", line 1024, in loadtxt 
    items = [conv(val) for (conv, val) in zip(converters, vals)] 
    File "/Users/zdlzdlxs/Library/Python/3.6/lib/python/site-packages/numpy/lib/npyio.py", line 1024, in <listcomp> 
    items = [conv(val) for (conv, val) in zip(converters, vals)] 
    File "/Users/zdlzdlxs/Library/Python/3.6/lib/python/site-packages/matplotlib/dates.py", line 287, in __call__ 
    return date2num(datetime.datetime(*time.strptime(s, self.fmt)[:6])) 
    File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/_strptime.py", line 559, in _strptime_time 
    tt = _strptime(data_string, format)[0] 
    File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/_strptime.py", line 329, in _strptime 
    raise TypeError(msg.format(index, type(arg))) 
TypeError: strptime() argument 0 must be str, not <class 'bytes'> 

我试图找到解决方案计算器但没有成功。 任何人都可以帮助我正确地转换日期时间？非常感谢。

Answer 1

此日期转换器需要一个常规字符串，它在Py3中是unicode。但loadtxt加载文本字节串：

In [12]: mdates.strpdate2num('%Y-%m-%d')(b'1999-01-31') 
--------------------------------------------------------------------------- 
.... 
TypeError: strptime() argument 0 must be str, not <class 'bytes'> 

修改转换器decode的字节字符串应该把这个问题的护理：

In [13]: fn = lambda astr: mdates.strpdate2num('%Y-%m-%d')(astr.decode()) 

In [14]: fn(b'1999-01-01') 
Out[14]: 729755.0 

测试中loadtxt：

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.])