解決Python代碼中的TypeError

Question

我基本上運行一些代碼如下。基本上，我只是從CSV文件中檢索成對的股票（按照行1-庫存1,2，行2-庫存1,2等等，其中庫存1和庫存2在每行中不同）。然後我從雅虎那裏收集與這些股票「對」相關的數據。我計算股票的回報，並基本檢查一對股票之間的距離（回報差異）是否違反了某個閾值，如果是，我返回1.但是，我收到以下我無法解決的錯誤：

PricePort(tickers) 
    27  for ticker in tickers: 
    28   #print ticker 
---> 29   x = pd.read_csv('http://chart.yahoo.com/table.csv?s=ttt'.replace('ttt',ticker),usecols=[0,6],index_col=0) 
    30   x.columns=[ticker] 
    31   final=pd.merge(final,x,left_index=True,right_index=True) 

TypeError: expected a character buffer object 

的代碼如下：

from datetime import datetime 
import pytz 
import csv 
import pandas as pd 
import pandas.io.data as web 
import numpy as np 

#Retrieves pairs of stocks (laid out as Row 1-Stock 1,2, Row 2-Stock 1,2 and so on, where Stock 1 and 2 are different in each row) from CSV File 
def Dataretriever(): 
     Pairs = [] 
     f1=open('C:\Users\Pythoncode\Pairs.csv') #Enter the location of the file 
     csvdata= csv.reader(f1) 
     for row in csvdata:   #reading tickers from the csv file 
      Pairs.append(row) 
     return Pairs 

tickers = Dataretriever() #Obtaining the data 

#Taking in data from Yahoo associated with these "Pairs" of Stocks 
def PricePort(tickers): 
    """ 
     Returns historical adjusted prices of a portfolio of stocks. 
     tickers=pairs 
    """ 
    final=pd.read_csv('http://chart.yahoo.com/table.csv?s=^GSPC',usecols=[0,6],index_col=0) 
    final.columns=['^GSPC'] 
    for ticker in tickers: 
     #print ticker 
     x = pd.read_csv('http://chart.yahoo.com/table.csv?s=ttt'.replace('ttt',ticker),usecols=[0,6],index_col=0) 
     x.columns=[ticker] 
     final=pd.merge(final,x,left_index=True,right_index=True) 
    return final 

#Calculating returns of the stocks 
def Returns(tickers): 
    l = [] 
    begdate=(2014,1,1) 
    enddate=(2014,6,1)  
    p = PricePort(tickers) 
    ret = (p.close[1:] - p.close[:-1])/p.close[1:] 
    l.append(ret) 
    return l 

#Basically a class to see if the distance (difference in returns) between a 
#pair of stocks breaches some threshold 
class ThresholdClass():  
    #constructor 
    def __init__(self, Pairs): 
     self.Pairs = Pairs 

    #Calculating the distance (difference in returns) between a pair of stocks 
    def Distancefunc(self, tickers): 
     k = 0 
     l = Returns(tickers) 
     summation=[[0 for x in range (k)]for x in range (k)]  #2d matrix for the squared distance 
     for i in range (k): 
      for j in range (i+1,k):  # it will be a upper triangular matrix 
       for p in range (len(self.PricePort(tickers))-1): 
        summation[i][j]= summation[i][j] + (l[i][p] - l[j][p])**2  #calculating distance 

     for i in range (k):  #setting the lower half of the matrix 1 (if we see 1 in the answer we will set a higher limit but typically the distance squared is less than 1) 
      for j in range (i+1): 
       sum[i][j]=1 
      return sum 

    #This function is used in determining the threshold distance 
    def MeanofPairs(self, tickers): 
     sum = self.Distancefunc(tickers) 
     mean = np.mean(sum) 
     return mean 

    #This function is used in determining the threshold distance 
    def StandardDeviation(self, tickers): 
     sum = self.Distancefunc(tickers) 
     standard_dev = np.std(sum) 
     return standard_dev 


    def ThresholdandnewsChecker(self, tickers): 
     threshold = self.MeanofPairs(tickers) + 2*self.StandardDeviation(tickers) 
     if (self.Distancefunc(tickers) > threshold): 
      return 1 

Threshold_Class = ThresholdClass(tickers) 
Threshold_Class.ThresholdandnewsChecker(tickers,1) 

Answer 1

麻煩的是Dataretriever()返回一個列表，而不是一個字符串。當您遍歷tickers()時，名稱ticker被綁定到一個列表。

str.replace方法預計這兩個參數都是字符串。下面的代碼引發錯誤，因爲第二個參數是一個列表：

'http://chart.yahoo.com/table.csv?s=ttt'.replace('ttt', ticker) 

下一行x.columns = [ticker]會造成類似的問題。在這裏，ticker需要是可哈希對象（如字符串或整數），但列表不可哈希。