尝试从二维列表（从 .txt 文件读取）中查找平均变化率时结果不正确
Incorrect results when trying to find average rate of change from a 2-dimensional list (read from a .txt file)
我创建了一个程序来读取由价格列表组成的 .txt 文件。该程序将创建一个二维列表来存储周数、价格和与前一周相比的变化。用户将输入所需的开始周和结束周。
如果用户将 'start week' 输入为“1”，将 'end week' 输入为“6”：
平均变化应该是“-0.30”
最高变化应该是 'week 4'，变化为“2.80”
最低的变化应该是 'week 5'，变化为 '-4.93'
然而，我的数字完全错了。
这是我的代码：
# 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 ()
作为参考，这里是 .txt 文件：
52.33
50.99
52.29
55.09
50.16
50.50
51.82
51.30
52.03
53.07
53.49
54.21
55.57
54.42
55.65
51.78
49.87
50.39
51.08
50.62
52.32
51.79
51.48
50.13
49.83
51.16
52.30
53.70
56.57
56.68
57.96
57.94
57.62
58.03
57.67
56.21
57.25
57.43
57.60
57.80
57.42
59.66
59.87
58.71
59.02
60.35
60.53
59.25
61.97
62.30
63.24
62.14
我认为这段代码应该可以满足您的要求：
# 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 ()
有几个问题，您迭代的范围向上移动了一个。这意味着，如果您尝试让开始周为 1，结束周为 2，那么实际上应该是 2 和 3。然后，您试图跟踪每个子数组的第三个条目中的变化百分比，然后再次对它们进行平均。相反，跟踪第三个条目中的幅度变化，然后在最后取平均值。
我会推荐这样的东西
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))
我创建了一个程序来读取由价格列表组成的 .txt 文件。该程序将创建一个二维列表来存储周数、价格和与前一周相比的变化。用户将输入所需的开始周和结束周。
如果用户将 'start week' 输入为“1”，将 'end week' 输入为“6”： 平均变化应该是“-0.30” 最高变化应该是 'week 4'，变化为“2.80” 最低的变化应该是 'week 5'，变化为 '-4.93'
然而，我的数字完全错了。
这是我的代码：
# 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 ()
作为参考，这里是 .txt 文件：
52.33
50.99
52.29
55.09
50.16
50.50
51.82
51.30
52.03
53.07
53.49
54.21
55.57
54.42
55.65
51.78
49.87
50.39
51.08
50.62
52.32
51.79
51.48
50.13
49.83
51.16
52.30
53.70
56.57
56.68
57.96
57.94
57.62
58.03
57.67
56.21
57.25
57.43
57.60
57.80
57.42
59.66
59.87
58.71
59.02
60.35
60.53
59.25
61.97
62.30
63.24
62.14
我认为这段代码应该可以满足您的要求：
# 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 ()
有几个问题，您迭代的范围向上移动了一个。这意味着，如果您尝试让开始周为 1，结束周为 2，那么实际上应该是 2 和 3。然后，您试图跟踪每个子数组的第三个条目中的变化百分比，然后再次对它们进行平均。相反，跟踪第三个条目中的幅度变化，然后在最后取平均值。
我会推荐这样的东西
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))