blocks|key|3275023|text|到目前为止，最简单的方法是使用itertools.islice。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3275024|with+open('myfile.text')+as+f:
++++lines+=+islice(f,+5,+11)|code-block|syntax|javascript|3275025|这一点的好处是它永远不会加载整个文件；它只会做它需要做的工作。|3275026|请注意，itertools中的函数很懒，所以您需要在关闭文件之前完成对行的处理，或者将islice包装在list()中强制求值。|3275027|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.python.org/2/library/itertools.html#itertools.islice^0|F|G|F|G|0|0|0|0|4|9|17|6|1G|6|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|F|3|G|5|H|7|12|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|13|8|@]|D|@]|E|$]]|$1|M|3|N|5|6|7|14|8|@$9|15|A|16|B|C]|$9|17|A|18|B|C]|$9|19|A|1A|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|1B|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]]]

By far the easiest way to do this is with <a href="https://docs.python.org/2/library/itertools.html#itertools.islice" rel="nofollow"><code>itertools.islice</code></a>:

<pre><code>with open('myfile.text') as f:
 lines = islice(f, 5, 11)
</code></pre>

The nice part about this is that it won't ever load the entire file; it'll do only as much work as it needs to.

Note that the functions in <code>itertools</code> are lazy, so you need to either finish working with the lines before you close the file, or wrap the <code>islice</code> in a <code>list()</code> to force evaluation.

blocks|key|3663062|text|把你已经有的单子切了怎么样。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3663063|with+open("myfile.txt")+as+myfile:
++++lines+=+[next(myfile).strip()+for+x+in+xrange(10)][5:10]|code-block|syntax|javascript|3663064|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

How about slicing the list that you already have.

<pre><code>with open("myfile.txt") as myfile:
 lines = [next(myfile).strip() for x in xrange(10)][5:10]
</code></pre>

blocks|key|2974317|text|例如，如果您知道要从何处开始，只需更改for循环中的范围。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2974318|var1+=+5
var2+=+10
for+x+in+range(var1,+var2):|code-block|syntax|javascript|2974319|会从5循环到10，当然你可以进一步调整变量。|2974320|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

If you know where you want to start just change the range in the for loop for example.

<pre><code>var1 = 5
var2 = 10
for x in range(var1, var2):
</code></pre>

would loop from 5 to 10, of course you can tweak your variables further.

blocks|key|2974356|text|我会这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2974357|>>>+with+open("myfile.txt")+as+myfile:
>>>++lines+=+myfile.read().split('\n')[5:10]|code-block|syntax|javascript|2974358|Split将逐行分隔成一个行数组，5:10将返回从5到10的数组元素，变量“line”将是一个数组，因此，要获得5到10行的字符串，可以：|2974359|>>>+with+open("myfile.txt")+as+myfile:
>>>++lines+=+'\n'.join(myfile.read().split('\n')[5:10])|2974360|这里唯一的区别是'\n'.join()部分，它只接受行数组中的每个元素，并将它们连接到一个由换行符分隔的字符串中。|2974361|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

I'd do something like this:

<pre><code>&gt;&gt;&gt; with open("myfile.txt") as myfile:
&gt;&gt;&gt; lines = myfile.read().split('\n')[5:10]
</code></pre>

Split will separate it line by line into an array of lines, and the [5:10] will return array elements from 5 to 10, the variable "lines" will be an array, however, so to just get a string of lines 5 to 10, you could:

<pre><code>&gt;&gt;&gt; with open("myfile.txt") as myfile:
&gt;&gt;&gt; lines = '\n'.join(myfile.read().split('\n')[5:10])
</code></pre>

The only difference here, is the '\n'.join() part, which just takes each element of the array of lines, and joins them into a string seperated by a newline.

blocks|key|2974363|text|读取文件，并将x到y行作为内容变量的列表：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2974364|with+open('content.txt')+as+f:
++++content=f.read().split('\n')[x-1:y]|code-block|syntax|javascript|2974365|注意'\n‘和’\r‘。|2974366|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Reads the file and takes lines x to y as a list to content variable:

<pre><code>with open('content.txt') as f:
 content=f.read().split('\n')[x-1:y]
</code></pre>

Take care of '\n' and '\r\n'.

The way to grab the first 10 lines of a text file could be done this way:

<pre><code>with open("myfile.txt") as myfile:
 lines = [next(myfile).strip() for x in xrange(10)]
</code></pre>

This will print the first 10 lines

But what if I only wanted lines 5-10? How would I do that?
The file isn't small, it's going to be big. I need an efficient way to do this.

Thank you.

Python - grab lines from text file, lines x-y

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

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抓取文本文件前10行的方法可以这样做：with open("myfile.txt") as myfile:        lines = [next(myfile).strip() for x in xrange(10)]这将打印前10行但如果我只想要5-10行呢？我该怎么做？文件不小，会很大。我需要一个有效的方法来做这件事。谢谢。

问Python -从文本文件抓取行，x-y行
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回答 5

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