在Python中从dict中删除某些键的最快方法

如果dict足够大,那么生成一个全新的dict是有意义的。

dict((k, v) for (k, v) in somedict.iteritems() if not k.startswith('someprefix'))

不仅是 del pop() :

$ python -m timeit -s "d = {'f':1,'foo':2,'bar':3}" "for k in d.keys():" "  if k.startswith('f'):" "    del d[k]"
1000000 loops, best of 3: 0.733 usec per loop

$ python -m timeit -s "d = {'f':1,'foo':2,'bar':3}" "for k in d.keys():" "  if k.startswith('f'):" "    d.pop(k)"
1000000 loops, best of 3: 0.742 usec per loop

$ python -m timeit -s "d = {'f':1,'foo':2,'bar':3}" "d1 = d.copy()"
1000000 loops, best of 3: 0.278 usec per loop

基于复制dict的基准:

$ python -m timeit -s "d = {'f':1,'foo':2,'bar':3}" "d1 = d.copy()" "for k in d1.keys():" "  if k.startswith('f'):" "    del d1[k]"
100000 loops, best of 3: 1.95 usec per loop

$ python -m timeit -s "d = {'f':1,'foo':2,'bar':3}" "d1 = d.copy()" "for k in d1.keys():" "  if k.startswith('f'):" "    d1.pop(k)"
100000 loops, best of 3: 2.15 usec per loop

减去复制成本,我们得到1.872 usec pop() 和1.672 德尔 .