检查多个字典键是否匹配的最pythonic方法是什么

Question

Suppose I have a dictionary my_dict .

What is the most pythonic way to check if my_dict['a'] == 'b' and my_dict['c'] == 'd' and my_dict['e'] == 'f' ?

I do not want it to throw any exception if the keys a , c or e don't exist in my_dict

Answer 1

You can form a tuple with Map and compare it. By Mapping the get method, missing keys will produce a None value and not crash.

(*map(my_dic.get,('a','c','e'),) == ('b','f','d')

Answer 2

You can zip values and keys together and use get() in a generator expression passed to all :

my_dict = {'a':'b', 'c':'d','e':'f'}

keys = ['a', 'c', 'e']
vals = ['b', 'd', 'f']

all(my_dict.get(k) == v for k, v in zip(keys, vals))
# true

This assumes values are not None , since get() returns None for missing values. If that's important, you can check for inclusion as well.

This will be False when keys are missing or values are different like:

my_dict = {'c':'d','e':'f'}

keys = ['a', 'c', 'e']
vals = ['b', 'd', 'f']

all(my_dict.get(k) == v for k, v in zip(keys, vals))
#False

Answer 3

Since this is a very simple use case, where the desired values have near identical character codes to the keys, you can use ord to get the numeric code point or ordinal for a single-character string, and chr to convert it back to a single-character string.

Note that the code point of b is one higher than a , for example.

>>> my_dict = {'a': 'b', 'c': 'd', 'e': 'f'}
>>> keys = ['a', 'c', 'e']
>>> all(my_dict.get(k) == chr(ord(k) + 1) for k in keys)
True

A similar approach using map , adapted from the answer above:

>>> list(map(my_dict.get, keys)) == [chr(ord(k) + 1) for k in keys]
True

Answer 4

I'll try to provide most understand-friendly and simple code at my opinion:

if my_dict.get('a') == 'b' and my_dict.get('c') == 'd' and my_dict.get('e') == 'f':
  print('all keys exist and values are correct')
else:
  print('one of keys is not exist or value of at least one key is not correct')

my_dict.get(key_name) return None if key_name not exist. b , d and f are not None .

About get method

Also you can catch error:

try:
  if my_dict['a'] == 'b' and my_dict['c'] == 'd' and my_dict['e'] == 'f':
    print('all keys exist and values are correct')
  else:
    print('all keys exist but some of values are not correct')
except KeyError:
  print('some of keys are not exist')

It is so basic but... I guess it is should be here because it basic