嘗試從二維列表中查找平均變化率（從.txt文件讀取）時，結果不正確

我創建了一個程序，它將讀取由價格列表組成的.txt文件。該計劃將創建一個2維列表來存儲週數，價格和前一週的變化。用戶將輸入所需的開始周和結束周。嘗試從二維列表中查找平均變化率（從.txt文件讀取）時，結果不正確

如果用戶要輸入的'開始一週爲「1」和「端周」爲「6」：的平均變化應該是「-0.30」的最高改變應該是「4周」隨着變化'2.80' 最低變化應該是'第5周'與變化'-4.93'

但是，我的數字出來完全錯誤。

這裏是我的代碼：

# get two dimensional list 
priceList = [] 

#open the file 
priceFile = open ('MicrosoftPrices.txt', 'r') 

#create variable for start year 
week = 1 
price = float (priceFile.readline()) 

#special case for week 1 

#initialize loop counter 
i = 0 

while price != '': 
    priceList.append ([0,0,0]) 

    priceList [i][0] = week 
    priceList [i][1] = float (price) 

    if week == 1: 
     priceList [i][2] = 0 
    else: 
     priceList[i][2] = ((priceList[i][1] - priceList[i-1][1])/priceList[i-1][1]) 

    #read the next line 
    price = priceFile.readline() 

    #add to the counter 
    i += 1 

    #go to next week 
    week = week + 1 

#initialize start and end weeks 
startWeek = 0 
endWeek = 0 

#define start week validation 
def FirstValidation (startWeek): 

    startWeek = -1 

    while startWeek == -1: 
     startWeek = input ('What week would you like to start with?') 

     try: 
      if startWeek == '': 
       startWeek = 1 
       break 

      startWeek = int (startWeek) 

     except Exception: 
      print ('Year must be a valid integer between 1 and 52') 

     else: 
      if startWeek >= 1 and startWeek <= 52: 
       break 
      else: 
       startWeek = -1 
       print ('ERROR: Week must be a valid integer between 1 and 52! Please try again.') 

    return startWeek 

#define end week validation 
def LastValidation (endWeek): 
    endWeek = -1 

    while endWeek == -1: 
     endWeek = input ('What week would you like to end with?') 

     try: 
      if endWeek == '': 
       endWeek = 52 
       break 

      endWeek = int (endWeek) 

     except Exception: 
      print ('Year must be a valid integer between 1 and 52') 
     else: 
      if endWeek >= startWeek and endWeek <= 52: 
       break 
      else: 
       endWeek = -1 
       print ('ERROR: Week must be a valid integer between 1 and 52! Please try again.') 

    return endWeek 

def main(): 

    #call week validations 
    startWeekVal = FirstValidation ('Start Week') 
    endWeekVal = LastValidation ('End Week') 


    #initialize min and max 
    maxChange = 0 
    minChange = 100 
    maxIndex = 0 
    minIndex = 0 
    total = 0 
    count = 0 

    for j in range (startWeekVal, endWeekVal +1): 
     if priceList [j][2] > maxChange: 
      maxChange = priceList [j][2] 
      maxIndex = j 
     if priceList [j][2] < minChange: 
      minChange = priceList [j][2] 
      minIndex = j 

     #calc average 
     total += priceList [j][2] 
     count += 1 

     #compute average 
     average = total/count 

    print ('Start Week:', startWeekVal) 
    print ('End Week:', endWeekVal) 
    print ('The average change is ', average) 
    print ('The week with the highest change is week' , priceList [maxIndex][0], 'with $', format (maxChange, '.2f')) 
    print ('The week with the lowest change is week' , priceList [minIndex][0], 'with $', format (minChange, '.2f')) 

    #close the file 
    priceFile.close() 

#call main 
main()

僅供參考，這裏是.txt文件：

來源

2017-03-27 Jeremy Mosier

應該在兩週之間的變化是價值觀的差異？你爲什麼分裂？ –

你是對的，我剛剛解決了這個問題。我現在正在獲取正確的最小值和最大值。仍然沒有得到正確的平均變化率。 –

您對平均變化率有什麼價值？ –

這段代碼，我想，應該做你想要什麼：

# get two dimensional list 
priceList = [] 

#open the file 
priceFile = open ('MicrosoftPrices.txt', 'r') 

#create variable for start year 
week = 1 
price = float (priceFile.readline()) 

#special case for week 1 

#initialize loop counter 
i = 0 

while price != '': 
    priceList.append ([0,0,0]) 

    priceList [i][0] = week 
    priceList [i][1] = float (price) 

    if week == 1: 
     priceList [i][2] = 0 
    else: 
     priceList[i][2] = (priceList[i][1] - priceList[i-1][1]) 

    #read the next line 
    price = priceFile.readline() 

    #add to the counter 
    i += 1 

    #go to next week 
    week = week + 1 

#initialize start and end weeks 
startWeek = 0 
endWeek = 0 

#define start week validation 
def FirstValidation (startWeek): 

    startWeek = -1 

    while startWeek == -1: 
     startWeek = input ('What week would you like to start with?') 

     try: 
      if startWeek == '': 
       startWeek = 1 
       break 

      startWeek = int (startWeek) 

     except Exception: 
      print ('Year must be a valid integer between 1 and 52') 

     else: 
      if startWeek >= 1 and startWeek <= 52: 
       break 
      else: 
       startWeek = -1 
       print ('ERROR: Week must be a valid integer between 1 and 52! Please try again.') 

    return startWeek 

#define end week validation 
def LastValidation (endWeek): 
    endWeek = -1 

    while endWeek == -1: 
     endWeek = input ('What week would you like to end with?') 

     try: 
      if endWeek == '': 
       endWeek = 52 
       break 

      endWeek = int (endWeek) 

     except Exception: 
      print ('Year must be a valid integer between 1 and 52') 
     else: 
      if endWeek >= startWeek and endWeek <= 52: 
       break 
      else: 
       endWeek = -1 
       print ('ERROR: Week must be a valid integer between 1 and 52! Please try again.') 

    return endWeek 

def main(): 

    #call week validations 
    startWeekVal = FirstValidation ('Start Week') 
    endWeekVal = LastValidation ('End Week') 


    #initialize min and max 
    maxChange = 0 
    minChange = 100 
    maxIndex = 0 
    minIndex = 0 
    total = 0 
    count = 0 

    print priceList 

    for j in range (startWeekVal-1, endWeekVal): 
     if priceList [j][2] > maxChange: 
      maxChange = priceList [j][2] 
      maxIndex = j 
     if priceList [j][2] < minChange: 
      minChange = priceList [j][2] 
      minIndex = j 

     #calc average 
     total += priceList [j][2] 
     count += 1 

     #compute average 

    average = total/count 

    print ('Start Week:', startWeekVal) 
    print ('End Week:', endWeekVal) 
    print ('The average change is ', average) 
    print ('The week with the highest change is week' , priceList [maxIndex][0], 'with $', format (maxChange, '.2f')) 
    print ('The week with the lowest change is week' , priceList [minIndex][0], 'with $', format (minChange, '.2f')) 

    #close the file 
    priceFile.close() 

#call main 
main()

有幾個問題，你迭代的範圍增加了一個。這意味着如果你試圖開始1周和結束2周，它實際上是2和3。然後，您試圖跟蹤每個子陣列的第三個條目中的更改百分比，然後再次對其進行平均。而是跟蹤第三項的大小變化，然後在最後平均。

來源

2017-03-27 18:57:34 WillySchu

我會推薦這樣的事情

def stats(y, start, stop): 
    maximum = max(y[start, stop]) 
    minimum = min(y[start, stop]) 
    average = sum(y[start, stop])/len(y[start, stop]) 
    return maximum, minimum, average 

with open('prices.txt') as f: 
    l = list(map(float, f.readlines())) 

x = l[0] 
y = [] 
for i in l: 
    y.append(i-x) 
    x=i 

#We now have two lists. l[i] has the price at week i, and 
    #y[i] has the change in price from week i-1 

start_week = int(input("Start Week: ")) -1 
end_week = int(input("End Week: ")) 

maximum, minimum, average = stats(y, start_week, end_week) 

print("Maximum {}".format(maximum)) 
print("Minimum {}".format(minimum)) 
print("Average {}".format(average))

來源

2017-03-27 19:02:21

嘗試從二維列表中查找平均變化率（從.txt文件讀取）時，結果不正確

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