Should I use 'has_key()' or 'in' on Python dicts? Should I use 'has_key()' or 'in' on Python dicts? python python

Should I use 'has_key()' or 'in' on Python dicts?


in wins hands-down, not just in elegance (and not being deprecated;-) but also in performance, e.g.:

$ python -mtimeit -s'd=dict.fromkeys(range(99))' '12 in d'10000000 loops, best of 3: 0.0983 usec per loop$ python -mtimeit -s'd=dict.fromkeys(range(99))' 'd.has_key(12)'1000000 loops, best of 3: 0.21 usec per loop

While the following observation is not always true, you'll notice that usually, in Python, the faster solution is more elegant and Pythonic; that's why -mtimeit is SO helpful -- it's not just about saving a hundred nanoseconds here and there!-)


According to python docs:

has_key() is deprecated in favor of key in d.


matomo