Question

我有一段代码来读取两个文件，将它们转换为集合，然后从另一个中减去一个集合。我想为＆＃34; a＆＃34;使用字符串变量（installedPackages）。而不是一个文件。我还想写一个＆＃34; c＆＃34;。

的变量

a = open("/home/user/packages1.txt")
b = open("/home/user/packages.txt")
c = open("/home/user/unique.txt", "w")

for line in set(a) - set(b):
    c.write(line)

a.close()
b.close()
c.close()

我尝试过以下操作但不起作用：

for line in set(installedPackages) - set(b):

我曾尝试使用StringIO，但我认为我使用不当。

最后，我是如何创建installedPackages：

的

stdout, stderr = p.communicate()
installedPackages = re.sub('\n$', '', re.sub('install$', '', re.sub('\t', '', stdout), 0,re.MULTILINE))

packages.txt示例：

humanity-icon-theme
hunspell-en-us
hwdata
hyphen-en-us
ibus
ibus-gtk
ibus-gtk3
ibus-pinyin
ibus-pinyin-db-android
ibus-table

Answer 1

如果要写入字符串缓冲区文件，请使用StringIO

>>> from StringIO import StringIO
>>> installed_packages = StringIO()
>>> installed_packages.write('test')
>>> installed_packages.getvalue()
'test'

Answer 2

set数据类型将iterable作为参数，因此如果installedPackages包含多个项目的字符串，则需要使用分隔符将其拆分。例如，以下代码将按所有逗号分隔字符串：

for line in set(installedPackages.split(',')) - set(b):
    c.write(line)

Answer 3

如下所示？

几次迭代后

编辑：

from subprocess import Popen, PIPE

DEBUG = True
if DEBUG:
    def log(msg, data):
        print(msg)
        print(repr(data))
else:
    def log(msg, data):
        pass

def setFromFile(fname):
    with open(fname) as inf:
        return set(ln.strip() for ln in inf)

def setFromString(s):
    return set(ln.strip() for ln in s.split("\n"))

def main():
    # get list of installed packages
    p = Popen(['dpkg', '--get-selections'], stdout=PIPE, stderr=PIPE)
    stdout, stderr = p.communicate()
    installed_packages = setFromString(stdout)

    # get list of expected packages
    known_packages = setFromFile('/home/john/packages.txt')

    # calculate the difference
    unknown_packages = installed_packages - known_packages
    unknown_packages_string = "\n".join(unknown_packages)

    log("Installed packages:", installed_packages)
    log("Known packages:", known_packages)
    log("Unknown packages:", unknown_packages)

if __name__=="__main__":
    main()

从变量而不是文件创建集合

3 个答案: