<p>通过调用slice创建一个slice,使用的字段与执行[start:end:step]表示法时使用的字段相同:</p>
<pre><code>sl = slice(0,4)
</code></pre>
<p>要使用切片,只需将其作为索引传递到列表或字符串中:</p>
<pre><code>>>> s = "ABCDEFGHIJKL"
>>> sl = slice(0,4)
>>> print(s[sl])
'ABCD'
</code></pre>
<p>假设您有一个固定长度文本字段的文件。您可以定义一个切片列表,以便轻松地从该文件中的每个“记录”中提取值。</p>
<pre><code>data = """\
0010GEORGE JETSON 12345 SPACESHIP ST HOUSTON TX
0020WILE E COYOTE 312 ACME BLVD TUCSON AZ
0030FRED FLINTSTONE 246 GRANITE LANE BEDROCK CA
0040JONNY QUEST 31416 SCIENCE AVE PALO ALTO CA""".splitlines()
fieldslices = [slice(*fielddef) for fielddef in [
(0,4), (4, 21), (21,42), (42,56), (56,58),
]]
fields = "id name address city state".split()
for rec in data:
for field,sl in zip(fields, fieldslices):
print("{} : {}".format(field, rec[sl]))
print('')
</code></pre>
<p>印刷品:</p>
<pre><code>id : 0010
name : GEORGE JETSON
address : 12345 SPACESHIP ST
city : HOUSTON
state : TX
id : 0020
name : WILE E COYOTE
address : 312 ACME BLVD
city : TUCSON
state : AZ
id : 0030
name : FRED FLINTSTONE
address : 246 GRANITE LANE
city : BEDROCK
state : CA
id : 0040
name : JONNY QUEST
address : 31416 SCIENCE AVE
city : PALO ALTO
state : CA
</code></pre>