在 Python 中拆分文件中的数据

Question

class Student:

    def __init__(self, name, hours, qpoints):
        self.name = name
        self.hours = float(hours)
        self.qpoints = float(qpoints)

    def getName(self):
        return self.name

    def getHours(self):
        return self.hours

    def getQPoints(self):
        return self.qpoints

    def gpa(self):
        return self.qpoints/self.hours

def makeStudent(infoStr):

    name, hours, qpoints = infoStr.split("\t")


    return Student(name, hours, qpoints)

def main():
    fileName = input("Enter file name: ")
    infile = open(fileName, "r")

    best = makeStudent(infile.readline())

    for line in infile:
        s = makeStudent(line)
        if s.gpa() > best.gpa():
            best = s

    infile.close()

    print("The best student is:", best.getName())
    print("hours:", best.getHours())
    print("GPA:", best.gpa())

if __name__ == '__main__':
    main()

我想从文本文件中读取行，用“\t”或“,”将其拆分，这样我就可以将它分配给变量，我得到 "ValueError: not enough values to unpack (expected 3, got 1) in makeStudent(infoStr) function. File I use is written correctly, I get same error if I edit file and code to ",”而不是“\t” “。为什么会这样？编辑：问题出在文本中跳过行。已解决。

Answer 1

有时 infoStr 行可能不包含您要拆分的字符（例如空行 ''）。将其包装在一个 try 块中，你应该没问题。

try:
    name, hours, qpoints = infoStr.split('\t')
except ValueError:
    name, hours, qpoints = None, None, None

然后您需要在实例化 Student 之前处理 None 情况。

Answer 2

请注意，您已经在 for line in infile 开始的块中迭代文件行，因此无需在 infile.readline() 内执行。

您还可以在将行格式发送到您的函数之前检查行格式（或检查函数中的格式，无论您喜欢什么）。

{truncated code}

# This loop will put on each iteration the next line of the file in the "line" var.
for line in infile:

    # You need two commas in your line to be able to split it in 3 values.
    if line.count(",") != 2:
        print("WARN: Invalid format in line: "+line)
        # Of course that you could implement some counter to identify
        # the problematic line location within the file...
        quit()

    s = makeStudent(line)
    if s.gpa() > best.gpa():
        best = s

{truncated code}

Answer 3

我敢打赌这是一个经典的制表符与 spaces 问题。由于 IDE 格式或搜索和替换失控，您的文件实际上可能 space 分开。

试试这个：

def makeStudent(infoStr):
    FAKE_TAB = '    '
    name, hours, qpoints = infoStr.split(FAKE_TAB)

    return Student(name, hours, qpoints)

如果这不起作用，请手动确定每行中每个值之间有多少 space，然后用它替换 FAKE_TAB。不可否认，这是一个略显粗略的补丁......

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