读入一个包含多个等级的文件，每个等级用逗号分隔，并打印出计算出的平均值

Question

问题：完成以下程序，它读入一个包含多个成绩的文件，每个成绩用逗号分隔，并打印出计算出的平均值。即写函数getGrades():和calculateAverage():

def main():
  grades = getGrades()   #get the file name containing the grades
                         #and return the contents of the file
  avg = calculateAverage(grades) #separate the grades into numbers and compute
                         #the average
  print("The calculated average is:", avg)
main()

我已经插入了给定的函数并编写了一个新程序，但是我有点困惑，而且我也遇到了错误。请帮忙！

def getGrades():
  filename = input("Please enter a file name: ")
  openfile = open(filename, "r")
  readfile = openfile.readlines()

  return readfile

def calculateAverage(n):
  totalGrades = []

  for i in (n):
    Split = list(map(int, i.split(",")))
    totalGrades += Split

  avg = sum(totalGrades)/float(len(totalGrades))

  return avg

def main():
  grades = getGrades()                  
  avg = calculateAverage(grades) 
  print("The calculated average is:", avg)
main()

Answer 1

在你的 calculateAverage() 函数中，你传递参数 n 但对于 for 循环你使用函数 getGrades() 的局部变量名称 readfile .

还有split is a list of strings. To convert them to integers to perform the summations you can use map()的结果。 map returns 一个迭代器，它将函数应用于可迭代的每个项目，产生结果。

要从您阅读的行中删除换行符和其他空格，您可以使用 rstrip().

最后，如果您的两个参数都是整数，要执行浮点除法，您必须将两者之一转换为 float。检查这个 answer.

最终程序如下所示：

def getGrades():
  filename = input("Please enter a file name: ")
  openfile = open(filename, "r")
  readfile = openfile.readlines()

  return readfile

def calculateAverage(n):
  total_grades = []
  for i in (n):
    line_grade = list(map(int, i.rstrip().split(",")))
    total_grades += line_grade
  avg = sum(total_grades)/float(len(total_grades))
  return avg

def main():
  grades = getGrades()                  
  avg = calculateAverage(grades) 
  print("The calculated average is:", avg)

if __name__ == "__main__":
  main()

如果您运行使用包含以下内容的测试文件： 5,10,15,20 你得到：

>>> 
Please enter a file name: test.txt
The calculated average is: 12.5
>>>

calculateAverage(n) 没有 map() 而有 list comprehensions 可以是：

def calculateAverage(n):
  total_grades = []
  for i in (n):
    line_grade = i.rstrip().split(",")
    line_grade = [int(x) for x in line_grade]
    total_grades += line_grade
  avg = sum(total_grades)/float(len(total_grades))
  return avg

最后你可以用简单的方式来做，并有一个 for 循环来将 split 返回的列表中的每个元素转换为整数：

def calculateAverage(n):
  total_grades = []
  for i in (n):
    line_grade = i.rstrip().split(",")
    for element in line_grade:
      total_grades.append(int(element))
  avg = sum(total_grades)/float(len(total_grades))
  return avg

读入一个包含多个等级的文件，每个等级用逗号分隔，并打印出计算出的平均值

Read in a file that has multiple grades, each separated by a comma, and prints out the computed average

python

average