Question

我有一个名为input.py的文件，其中包含以下内容：

#This is a file of categories
Animals:    cat, dog, frog, cheetah, tiger
Items:      desk, chair, bus, cups, pencil

Technology: cellphone, TV, laptop, wifi-router
    #That's the end of the file

我希望过滤掉所有以#开头的空行和行，以生成output.py：

Animals:    cat, dog, frog, cheetah, tiger
Items:      desk, chair, bus, cups, pencil
Technology: cellphone, TV, laptop, wifi-router

我的代码是

with open('input.py', 'r') as infile, open('output.py', 'w') as outfile:
    for line in infile:
        if line[0].strip('') == '#' or line == '\n':
            pass
        else:
            outfile.write(line)

但它不会从标签开始剥离线条。我尝试用.strip('')替换.strip('\t')，但我得到了相同的输出：

Animals:    cat, dog, frog, cheetah, tiger
Items:      desk, chair, bus, cups, pencil
Technology: cellphone, TV, laptop, wifi-router
    #That's the end of the file

为什么.strip('')或.strip('\t')没有剥离标签？

Answer 1

Strip方法只能从字符串的开头或结尾删除字符。请尝试使用替换。

>>> line = "Animals:    cat, dog, frog, cheetah, tiger"
>>> line.replace('\t', ' ')
'Animals: cat, dog, frog, cheetah, tiger'

Answer 2

您忘记在strip条件下实际应用else适用的行。此外，使用str.startswith来测试您的行是否以特定字符串开头。

这是一个完整的例子：

from io import StringIO

mystr = StringIO("""Animals:    cat, dog, frog, cheetah, tiger
Items:      desk, chair, bus, cups, pencil

Technology: cellphone, TV, laptop, wifi-router
    #That's the end of the file""")

with mystr as infile:
    for line in infile:
        if line.strip().startswith('#') or line == '\n':
            pass
        else:
            print(line.strip())

结果：

Animals:    cat, dog, frog, cheetah, tiger
Items:      desk, chair, bus, cups, pencil
Technology: cellphone, TV, laptop, wifi-router

试图理解.strip

2 个答案: