Python 3.x：转到下一行

Question

我有一个小脚本，它从.html文件中提取一些文本。

f = open(local_file,"r")
for line in f:
    searchphrase = '<span class="position'
    if searchphrase in line:
        print("found it\n")

这对我来说很好（错误处理将在以后导入），我的问题是我要提取的文本在搜索短语之后跟随2行。 如何在.html文件中向下移动2行？

Answer 1

您可以通过在其上调用next()两次将f （可迭代）推进两行：

with open(local_file,"r") as f
    for line in f:
        searchphrase = '<span class="position'
        if searchphrase in line:
            print("found it\n")
            next(f) # skip 1 line
            return next(f)  # and return the line after that.

但是 ，如果你试图解析HTML，请考虑使用HTML解析器来代替 。 例如，使用BeautifulSoup 。

Answer 2

这对我很好：

f = open(local_file,"r")
found = -1
for line in f:
    if found == 2:
        print("Line: "+line);
        break
    elif found > 0:
        found += 1
    else:
        searchphrase = '<span class="position'
        if searchphrase in line:
            print("found it")
            found = 1

输入文件是：

bla
<span class="position">Hello</span>
blub
that's it
whatever

以及该计划的输出：

found it
Line: that's it

你可以将found重置为-1来搜索模式的更多出现，而不是调用break 。