Lambda function to get an element in a nested dict, specifying a dot separated key path (and generalization to any separator and method)

keypath_get.py

from functools import reduce

# The simple dotpath version
dotpath_get = lambda d, dotpath: reduce(lambda x, y: x.get(y), dotpath.split('.'), d)

# A generalization to any separator and any "get" method:

keypath_get = lambda d, keypath, sep, getmethod: reduce(lambda x, y: getattr(x, getmethod)(y), keypath.split(sep), d)

Usage

>>> assert dotpath_get(d, 'a.b')
3
>>> import os
>>> assert keypath_get(os, 'path.sep', '.', '__getattribute__') == os.path.sep
>>> assert keypath_get(os, 'path/curdir', '/', '__getattribute__') == os.path.curdir
>>> assert keypath_get(os, 'path,exists,__annotations__', ',', '__getattribute__') == os.path.exists.__annotations__