suggestions, comments on an "is_subdict" test

[Vlastimil Brom]

Hi all,
I'd like to ask for comments or advice on a simple code for testing a
"subdict", i.e. check whether all items of a given dictionary are
present in a reference dictionary.
Sofar I have:

def is_subdict(test_dct, base_dct):
"""Test whether all the items of test_dct are present in base_dct."""
unique_obj = object()
for key, value in test_dct.items():
if not base_dct.get(key, unique_obj) == value:
return False
return True

I'd like to ask for possibly more idiomatic solutions, or more obvious
ways to do this. Did I maybe missed some builtin possibility?
I am unsure whether the check against an unique object() or the
negated comparison are usual.?
(The builtin exceptions are ok, in case anything not dict-like is
passed. A cornercase like >>> is_subdict({}, 4)doesen't seem to be worth a special check just now.)

Thanks in advance for the suggestions,
regards,
vbr

 

[Irmen de Jong]

Hi all,
I'd like to ask for comments or advice on a simple code for testing a
"subdict", i.e. check whether all items of a given dictionary are
present in a reference dictionary.
Sofar I have:

def is_subdict(test_dct, base_dct):
"""Test whether all the items of test_dct are present in base_dct."""
unique_obj = object()
for key, value in test_dct.items():
if not base_dct.get(key, unique_obj) == value:
return False
return True

I'd like to ask for possibly more idiomatic solutions, or more obvious
ways to do this. Did I maybe missed some builtin possibility?

I would use:

test_dct.items() <= base_dct.items()

-irmen

 

[MRAB]

I would use:

test_dct.items()<= base_dct.items()

In Python 2:
False

In Python 3:
True

YMMV

 

[Raymond Hettinger]

In Python 2:

 >>> test_dct = {"foo": 0, "bar": 1}
 >>> base_dct = {"foo": 0, "bar": 1, "baz": 2}
 >>>
 >>> test_dct.items() <= base_dct.items()
False

In Python 3:

 >>> test_dct = {"foo": 0, "bar": 1}
 >>> base_dct = {"foo": 0, "bar": 1, "baz": 2}
 >>> test_dct.items() <= base_dct.items()
True

YMMV

That is because it is spelled differently in Python 2.7:
True

Raymond

 

[Paul Rubin]

I would use:
test_dct.items() <= base_dct.items()

I think you need an explicit cast:

set(test_dct.items()) <= set(base_dct.items())