an easy way to mock loosely defined python dict objects

For example, testing a dict object like described above, can then be expressed as

>>> from mock
import Mock
   >>>
   from any_valid
import AnyValid, Int, OneOf
   >>>
   valid_bar = {
      ...'baz': AnyValid(Int(min = -3, max = 14)),
      ...'qux': AnyValid(OneOf(['yes', 'no'])),
      ...
   } >>>
   mock = Mock(return_value = None) >>>
   mock('foo', bar = {
      'baz': 4,
      'qux': 'yes'
   }) >>>
   mock.assert_called_once_with('foo', bar = valid_bar) >>>

Suggestion : 2

To create an empty dictionary, first create a variable name which will be the name of the dictionary.,To learn more about the Python programming language, check out freeCodeCamp's Scientific Computing with Python Certification.,Our mission: to help people learn to code for free. We accomplish this by creating thousands of videos, articles, and interactive coding lessons - all freely available to the public. We also have thousands of freeCodeCamp study groups around the world.,When it comes to values inside a Python dictionary there are no restrictions. Values can be of any data type - that is they can be both of mutable and immutable types.

Then, assign the variable to an empty set of curly braces, {}.

#create an empty dictionary
my_dictionary = {}

print(my_dictionary)

#to check the data type use the type() function
print(type(my_dictionary))

#output

#{}
#<class 'dict'>

It acts as a constructor and creates an empty dictionary:

#create an empty dictionary
my_dictionary = dict()

print(my_dictionary)

#to check the data type use the type() function
print(type(my_dictionary))

#output

#{}
#<class 'dict'>

The general syntax for this is the following:

dictionary_name = {
   key: value
}

You would achieve this by using dict() and passing the curly braces with the sequence of key-value pairs enclosed in them as an argument to the function.

#create a dictionary with dict()
my_information = dict({'name': 'Dionysia' ,'age': 28,'location': 'Athens'})

print(my_information)

#check data type
print(type(my_information))

#output

#{'name': 'Dionysia', 'age': 28, 'location': 'Athens'}
#<class 'dict'>

The general syntax for the method is the following:

dictionary_name = dict.fromkeys(sequence, value)

Suggestion : 3

Method 4 — Dictionary comprehension {k:v for (k,v) in dict.items() if condition} is the most Pythonic and fastest way to filter a dictionary in Python.,The best way to filter a dictionary in Python is to use the powerful method of dictionary comprehension.,The answer is no! Read on to learn about a more generic way to make filtering a dictionary as easy as calling a function passing the dictionary and the filter function. ,Now, you know the basic method of filtering a dictionary in Python (by key and by value). But can we do better? What if you need to filter many dictionaries by many different filtering conditions? Do we have to rewrite the same code again and again?

You start with the following dictionary of names:

names = {
   1: 'Alice',
   2: 'Bob',
   3: 'Carl',
   4: 'Ann',
   5: 'Liz'
}

You want to keep those (key, value) pairs where key meets a certain condition (such as key%2 == 1).

newDict = dict()

# Iterate over all(k, v) pairs in names
for key, value in names.items():

   # Is condition satisfied ?
   if key % 2 == 1:
   newDict[key] = value

Let’s have a look at the output:

print(newDict)
# {
   1: 'Alice',
   3: 'Carl',
   5: 'Liz'
}

Let’s create the generic filter function!

def filter_dict(d, f):
   ''
' Filters dictionary d by function f. '
''
newDict = dict()

# Iterate over all(k, v) pairs in names
for key, value in d.items():

   # Is condition satisfied ?
   if f(key, value):
   newDict[key] = value

return newDict

If you want to accomplish the same thing as above—filtering by key to include only odd keys—you simply use the following one-liner call:

print(filter_dict(names, lambda k, v: k % 2 == 1))
# {
   1: 'Alice',
   3: 'Carl',
   5: 'Liz'
}