Python提供了一些复合数据类型,比较常用的一种就是List。List支持异构数据。比如:
>>> a = ['spam', 'eggs', 100, 1234] >>> a ['spam', 'eggs', 100, 1234]
List和String一样,支持slice方式的下标和一些基本运算:
3*a[:3] + ['Boe!'] ['spam', 'eggs', 100, 'spam', 'eggs', 100, 'spam', 'eggs', 100, 'Boe!']
List和String不同在于,List的内容是可变的,前提是元素是可变类型:
>>> a[2] = a[2] + 23 >>> a ['spam', 'eggs', 123, 1234]
还可以插入,删除,替换部分元素:
>>> # Replace some items:
... a[0:2] = [1, 12]
>>> a
[1, 12, 123, 1234]
>>> # Remove some:
... a[0:2] = []
>>> a
[123, 1234]
>>> # Insert some:
... a[1:1] = ['bletch', 'xyzzy']
>>> a
[123, 'bletch', 'xyzzy', 1234]
>>> a[:0] = a # Insert (a copy of) itself at the beginning
>>> a
[123, 'bletch', 'xyzzy', 1234, 123, 'bletch', 'xyzzy', 1234]
比较常用的两个函数是len()和append()。另外List的元素可以是另一个List:
>>> q = [2, 3]
>>> p = [1, q, 4]
>>> len(p)
3
>>> p[1]
[2, 3]
>>> p[1][0]
2
>>> p[1].append('xtra') # See section 5.1
>>> p
[1, [2, 3, 'xtra'], 4]
>>> q
[2, 3, 'xtra']
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