dict1={1:[1,11,111],2:[2,22,222]}
dict2={3:[3,33,333],4:[4,44,444]}
合并两个字典得到类似
{1:[1,11,111],2:[2,22,222],3:[3,33,333],4:[4,44,444]}
方法1:
dictMerged1=dict(dict1.items()+dict2.items())
方法2:
dictMerged2=dict(dict1, **dict2)
方法2等同于:
dictMerged=dict1.copy()
dictMerged.update(dict2)
或者
dictMerged=dict(dict1)
dictMerged.update(dict2)
方法2比方法1速度快很多,用timeit测试如下
$ python -m timeit -s 'dict1=dict2=dict((i,i) for i in range(100))' 'dictMerged1=dict(dict1.items()+dict2.items())'
10000 loops, best of 3: 20.7 usec per loop
$ python -m timeit -s 'dict1=dict2=dict((i,i) for i in range(100))' 'dictMerged2=dict(dict1,**dict2)'
100000 loops, best of 3: 6.94 usec per loop
$ python -m timeit -s 'dict1=dict2=dict((i,i) for i in range(100))' 'dictMerged3=dict(dict1)' 'dictMerged3.update(dict2)'
100000 loops, best of 3: 7.09 usec per loop
$ python -m timeit -s 'dict1=dict2=dict((i,i) for i in range(100))' 'dictMerged4=dict1.copy()' 'dictMerged4.update(dict2)'
100000 loops, best of 3: 6.73 usec per loop
list新增元素使用append方法。并不像php中 直接$array[]='xxx';
>>> a=[]
>>> a.append('bbb');
>>> b={'test':'bbbbbbbbbbb'}
>>> a.append(b);
>>> a
['bbb', {'test': 'bbbbbbbbbbb'}]
>>> c={'cc':"cccccccccccc"}
>>> a[4]=100
Traceback (most recent call last):
File "", line 1, in
IndexError: list assignment index out of range
>>> print a
['bbb', {'test': 'bbbbbbbbbbb'}]
>>> a[2]=100
Traceback (most recent call last):
File "", line 1, in
IndexError: list assignment index out of range
>>> a[1]=100
>>> print a
['bbb', 100]
>>> a[4]=100
Traceback (most recent call last):
File "", line 1, in
IndexError: list assignment index out of range