python - 没有在 python 中给出所需的输出

Question

这个程序应该读取一个输入文件，该文件有一个名为 year 的类别。因此，如果用户键入 198，则输出应给出其中包含 198 的所有年份，例如1981,1982,...等等但是，输出也在回升 199

Sierra Leone       WB_LI    0 Africa    1992
Sierra Leone       WB_LI    0 Africa    1993
Sierra Leone       WB_LI    0 Africa    1994
Sierra Leone       WB_LI    0 Africa    1995
Sierra Leone       WB_LI    0 Africa    1996
Sierra Leone       WB_LI    0 Africa    1997

文件的每一行包含以下字段，字段之间有一个空格:国家(50 个字符)收入水平(6 个字符)疫苗接种百分比(3 个字符)地区(25 个字符)年份(4 个字符)。因此，我总共有 92 个字符，我将遍历 88 个选区中的每个字符，并将它们与年份中的字符匹配以找到所需的年份。我想我的逻辑可能有一些错误，这也以 199 为例。我不应该使用列表或元组。只是归档。

这是我对我的代码所做的:

def main():

    #checks if the input file exists or not.
    #If the file exists, then the program breaks out of the loop and
    #moves on. Otherwise, the program halts with an IOError message. 
    while True:
        try:
            input_file=open('measles.txt','r')
            break
        except IOError:
            print("Error opening file:",input_file)
            break

    f2=input("What is the name of the output file? ")

    #checks if the output file exists or not.
    #If the file exists, then the program breaks out of the loop and
    #moves on. Otherwise, the program halts with an IOError message. 
    while True:
        try:
            output_file=open(f2,'w')
            break
        except IOError:
            print("Error opening file:",output_file)
            break

    #for loop prints all lines of the input file to the output file.
 year=str(input('Input year: '))
    line=input_file.readline().strip()

    while line!="":
        for line in input_file:

            if year==line[88:92]:
                output_file.write(line)            
            elif year==line[88:91]:
                output_file.write(line)
            elif year==line[88:90]:
                output_file.write(line) 
            elif year==line[88:89]:
                output_file.write(line)            
            elif year.lower()=="all" or year=="''" or year=='""':
                print(line)

        line=input_file.readline().strip()


    input_file.close()
    output_file.close()

main()

有人可以看看我的代码并指出问题吗？谢谢这是我正在处理的文件的几行。

Afghanistan                                        WB_LI   11 Eastern Mediterranean     1980
Afghanistan                                        WB_LI    0 Eastern Mediterranean     1981
Afghanistan                                        WB_LI    8 Eastern Mediterranean     1982
Afghanistan                                        WB_LI    9 Eastern Mediterranean     1983
Afghanistan                                        WB_LI   14 Eastern Mediterranean     1984
Afghanistan                                        WB_LI   14 Eastern Mediterranean     1985
Afghanistan                                        WB_LI   14 Eastern Mediterranean     1986
Afghanistan                                        WB_LI   31 Eastern Mediterranean     1987
Afghanistan                                        WB_LI   34 Eastern Mediterranean     1988
Afghanistan                                        WB_LI   22 Eastern Mediterranean     1989
Afghanistan                                        WB_LI   20 Eastern Mediterranean     1990
Afghanistan                                        WB_LI   19 Eastern Mediterranean     1991
Afghanistan                                        WB_LI   22 Eastern Mediterranean     1992
Afghanistan                                        WB_LI   25 Eastern Mediterranean     1993
Afghanistan                                        WB_LI   40 Eastern Mediterranean     1994
Afghanistan                                        WB_LI   41 Eastern Mediterranean     1995
Afghanistan                                        WB_LI   42 Eastern Mediterranean     1996
Afghanistan                                        WB_LI   38 Eastern Mediterranean     1997
Afghanistan                                        WB_LI   31 Eastern Mediterranean     1998
Afghanistan                                        WB_LI   31 Eastern Mediterranean     1999
Afghanistan                                        WB_LI   27 Eastern Mediterranean     2000
Afghanistan                                        WB_LI   37 Eastern Mediterranean     2001
Afghanistan                                        WB_LI   35 Eastern Mediterranean     2002
Afghanistan                                        WB_LI   39 Eastern Mediterranean     2003
Afghanistan                                        WB_LI   48 Eastern Mediterranean     2004
Afghanistan                                        WB_LI   50 Eastern Mediterranean     2005
Afghanistan                                        WB_LI   53 Eastern Mediterranean     2006
Afghanistan                                        WB_LI   55 Eastern Mediterranean     2007
Afghanistan                                        WB_LI   59 Eastern Mediterranean     2008
Afghanistan                                        WB_LI   60 Eastern Mediterranean     2009
Afghanistan                                        WB_LI   62 Eastern Mediterranean     2010
Afghanistan                                        WB_LI   65 Eastern Mediterranean     2011
Afghanistan                                        WB_LI   68 Eastern Mediterranean     2012
Albania                                            WB_LMI  90 Europe                    1980
Albania                                            WB_LMI  90 Europe                    1981
Albania                                            WB_LMI  93 Europe                    1982
Albania                                            WB_LMI  96 Europe                    1983
Albania                                            WB_LMI  96 Europe                    1984
Albania                                            WB_LMI  96 Europe                    1985
Albania                                            WB_LMI  96 Europe                    1986
Albania                                            WB_LMI  96 Europe                    1987
Albania                                            WB_LMI  96 Europe                    1988
Albania                                            WB_LMI  96 Europe                    1989
Albania                                            WB_LMI  88 Europe                    1990
Albania                                            WB_LMI  80 Europe                    1991
Albania                                            WB_LMI  87 Europe                    1992
Albania                                            WB_LMI  76 Europe                    1993
Albania                                            WB_LMI  90 Europe                    1994
Albania                                            WB_LMI  91 Europe                    1995
Albania                                            WB_LMI  92 Europe                    1996
Albania                                            WB_LMI  95 Europe                    1997
Albania                                            WB_LMI  89 Europe                    1998
Albania                                            WB_LMI  85 Europe                    1999
Albania                                            WB_LMI  95 Europe                    2000
Albania                                            WB_LMI  95 Europe                    2001
Albania                                            WB_LMI  96 Europe                    2002
Albania                                            WB_LMI  93 Europe                    2003

Answer 1

正如我在评论中提到的，您提供的输入与您的描述不符。您的代码显示从索引 88 开始的 year 字段，但您提供的输入只有 44 个字符长。我将从那里开始。

编辑:假设您不能使用任何容器，这就是我编写您的程序的方式。

def filter_results(input_file, output_file, year):
    for line in input_file:
        if not line: continue # skips if the line is blank
        if year == '' or line[88:92].startswith(year) or year.lower() == 'all':
            output_file.write(line+"\n")

def main():
    year = input("Give me a year: ")

    try: infile = open('measles.txt','r')
    except IOError: print("Error opening file: measles.txt")

    try: outfile = open(input("Name of output file?"),'w')
    except IOError: print("Error opening output file")

    try: infile,outfile
    except NameError: raise IOError("One of the files could not be opened")

    filter_results(infile,outfile,year)

    outfile.close()
    infile.close()

main()

就是说，我会先读入文件并将其写入 dict。像这样的东西:

lines = list()
with open('path/to/input_file') as input_file:
    for line in input_file:
        lines.append(
            {"country":line[0:51].strip(),
            "income":line[52:58].strip(),
            "vaccinated":line[59:62].strip(),
            "region":line[63:88].strip(),
            "year":line[89:93].strip()}
        # I may have screwed up that string splicing -- do one and doublecheck
year = input("Enter a four-digit year (or part thereof): ")
filtered_list = [line for line in lines if line['year'].startswith(year)]

您现有的代码也存在一些问题。

while True:
    try:
        input_file = open("measles.txt")
        break # ?
    except IOError:
        print("Error opening file:",input_file)
        break # ?

如果我们总是在一次迭代后中断，为什么我们要在这里循环？删除 while True 并只是 try:except 而没有 break。如果你需要在异常时停止程序，那么只需执行 except IOError: raise