python - 类型错误 : join() argument must be str or bytes, 不是 'NoneType'

Question

我不断收到以下错误，有人可以告诉我我做错了什么吗？

Traceback (most recent call last):
  File "generate_simulated_pair.py", line 50, in <module>
    outfile = open(os.path.join(settings.CSV_DATA_DIR ,"%s_%s.csv"%(pair, d.strftime ("%Y%m%d")
  File "C:\Program Files\Python35\lib\ntpath.py", line 113, in join
    genericpath._check_arg_types('join', path, *paths)
  File "C:\Program Files\Python35\lib\genericpath.py", line 143, in _check_arg_types
    (funcname, s.__class__.__name__)) from None
TypeError: join() argument must be str or bytes, not 'NoneType'

请参阅下面的内容，这是用于从 oanda 创建 CSV 文件以进行回测

from __future__ import print_function

import calendar
import copy
import datetime
import os, os.path
import sys

import numpy as np
import pandas as pd
import pandas_datareader

from pandas_datareader import data, wb
from qsforex import settings


def month_weekdays(year_int, month_int):
 """
Produces a list of datetime.date objects representing the
weekdays in a particular month, given a year.
"""
cal = calendar.Calendar()
return [d for d in cal.itermonthdates(year_int, month_int)if d.weekday() < 5 and d.year == year_int]


if __name__ == "__main__":
    try:
    pair = sys.argv[1]
except IndexError:
    print("You need to enter a currency pair, e.g. GBPUSD, as a command line parameter.")
else:
    np.random.seed(42)  # Fix the randomness

    S0 = 1.5000
    spread = 0.002
    mu_dt = 1400  # Milliseconds
    sigma_dt = 100  # Millseconds
    ask = copy.deepcopy(S0) + spread / 2.0
    bid = copy.deepcopy(S0) - spread / 2.0
    days = month_weekdays(2014, 1)  # January 2014
    current_time = datetime.datetime(
        days[0].year, days[0].month, days[0].day, 0, 0, 0,
    )

    # Loop over every day in the month and create a CSV file
    # for each day, e.g. "GBPUSD_20150101.csv"
    for d in days:
        print(d.day)
        current_time = current_time.replace(day=d.day)
        outfile = open(os.path.join(settings.CSV_DATA_DIR ,"%s_%s.csv"%(pair, d.strftime ("%Y%m%d")
                )
            ), 
        "wb")
        outfile.write("Time,Ask,Bid,AskVolume,BidVolume\n")     

        # Create the random walk for the bid/ask prices
        # with fixed spread between them
        while True:
            dt = abs(np.random.normal(mu_dt, sigma_dt))
            current_time += datetime.timedelta(0, 0, 0, dt)
            if current_time.day != d.day:
                outfile.close()
                break
            else:
                W = np.random.standard_normal() * dt / 1000.0 / 86400.0
                ask += W
                bid += W
                ask_volume = 1.0 + np.random.uniform(0.0, 2.0)
                bid_volume = 1.0 + np.random.uniform(0.0, 2.0)
                line = "%s,%s,%s,%s,%s\n" % (
                    current_time.strftime("%d.%m.%Y %H:%M:%S.%f")[:-3], 
                    "%0.5f" % ask, "%0.5f" % bid,
                    "%0.2f00" % ask_volume, "%0.2f00" % bid_volume
                )
                outfile.write(line)

Answer 1

settings.CSV_DATA_DIR是 None，所以 os.path.join(settings.CSV_DATA_DIR, ...)失败。

为了将来引用，请查看回溯并按照堆栈返回您自己的代码；您的回溯始于:

  File "generate_simulated_pair.py", line 50, in <module>
    outfile = open(os.path.join(settings.CSV_DATA_DIR ,"%s_%s.csv"%(pair, d.strftime ("%Y%m%d")

底部的异常告诉您:

join() argument must be str or bytes, not 'NoneType'

所以 os.path.join() 的参数之一是 None值(value)。在您传入的两个参数中，第二个绝对是字符串，只剩下一个选项:另一个参数 必须是 None .