python - Test if dict contained in dict -

testing equality works fine python dicts:

first  = {"one":"un", "two":"deux", "three":"trois"} second = {"one":"un", "two":"deux", "three":"trois"}  print(first == second) # result: true 

but second dict contains additional keys want ignore:

first  = {"one":"un", "two":"deux", "three":"trois"} second = {"one":"un", "two":"deux", "three":"trois", "foo":"bar"} 

is there simple way test if first dict part of second dict, keys , values?

edit 1:

this question suspected duplicate of how test if dictionary contains keys, i'm interested in testing keys and values. containing same keys not make 2 dicts equal.

edit 2:

ok, got answers using 4 different methods, , proved of them working. need fast process, tested each execution time. created 3 identical dicts 1000 items, keys , values random strings of length 10. second , third got key-value pairs, , last non-extra key of third got new value. so, first subset of second, not of third. using module timeit 10000 repetitions, got:

method                                                      time [s]    first.viewitems() <=second.viewitems()                           0.9  set(first.items()).issubset(second.items())                      7.3 len(set(first.items()) & set(second.items())) == len(first)      8.5 all(first[key] == second.get(key, sentinel) key in first)    6.0 

i guessed last method slowest, it's on place 2. method 1 beats them all.

thanks answers!

you can use dictionary view:

# python 2 if first.viewitems() <= second.viewitems():     # true if `first` subset of `second`  # python 3 if first.items() <= second.items():     # true if `first` subset of `second` 

dictionary views standard in python 3, in python 2 need prefix standard methods view. act sets, , <= tests if 1 of subset of (or equal to) another.

demo in python 3:

>>> first  = {"one":"un", "two":"deux", "three":"trois"} >>> second = {"one":"un", "two":"deux", "three":"trois", "foo":"bar"} >>> first.items() <= second.items() true >>> first['four'] =  'quatre' >>> first.items() <= second.items() false 

this works non-hashable values too, keys make key-value pairs unique already. documentation little confusing on point, mutable values (say, lists) works:

>>> first_mutable = {'one': ['un', 'een', 'einz'], 'two': ['deux', 'twee', 'zwei']} >>> second_mutable = {'one': ['un', 'een', 'einz'], 'two': ['deux', 'twee', 'zwei'], 'three': ['trois', 'drie', 'drei']} >>> first_mutable.items() <= second_mutable.items() true >>> first_mutable['one'].append('ichi') >>> first_mutable.items() <= second_mutable.items() false 

you use all() function generator expression; use object() sentinel detect missing values concisely:

sentinel = object() if all(first[key] == second.get(key, sentinel) key in first):     # true if `first` subset of `second` 

but isn't readable , expressive using dictionary views.