Python Dictionary

thisdict = {  
  "brand": "Ford",  
  "model": "Mustang",  
  "year": 1964  
}

Dictionaries are used to store data values in key:value pairs. A dictionary is a collection which is ordered*, changeable and do not allow duplicates.

As of Python version 3.7, dictionaries are ordered. In Python 3.6 and earlier, dictionaries are unordered.

thisdict = {  
  "brand": "Ford",  
  "model": "Mustang",  
  "year": 1964  
}  
print(thisdict)
 
# {'brand': 'Ford', 'model': 'Mustang', 'year': 1964}

Dictionary Items

• Dictionary items are ordered, changeable, and do not allow duplicates.
• Dictionary items are presented in key:value pairs, and can be referred to by using the key name.

thisdict = {  
  "brand": "Ford",  
  "model": "Mustang",  
  "year": 1964  
}  
print(thisdict["brand"])
 
# Ford

The dict() Constructor

thisdict = dict(name = "John", age = 36, country = "Norway")  
print(thisdict)

Accessing Items

thisdict = {
	"brand": "Ford",
	"model": "Mustang",
	"year": 1964
}
 
x = thisdict["model"]

Get Items

The items() method will return each item in a dictionary, as tuples in a list.

thisdict = {
  "brand": "Ford",
  "model": "Mustang",
  "year": 1964
}
 
x = thisdict.items()
 
print(x)
# dict_items([('brand', 'Ford'), ('model', 'Mustang'), ('year', 1964)])

car = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}
 
x = car.items()
 
print(x) #before the change
 
car["year"] = 2020
 
print(x) #after the change
 
# dict_items([('brand', 'Ford'), ('model', 'Mustang'), ('year', 1964)])  
# dict_items([('brand', 'Ford'), ('model', 'Mustang'), ('year', 2020)])

thisdict = {
  "brand": "Ford",
  "model": "Mustang",
  "year": 1964
}
if "model" in thisdict:
  print("Yes, 'model' is one of the keys in the thisdict dictionary")
 
# Yes, 'model' is one of the keys in the thisdict dictionary

Change Values

thisdict =	{
  "brand": "Ford",
  "model": "Mustang",
  "year": 1964
}
 
thisdict["year"] = 2018
 
print(thisdict)
 
# {'brand': 'Ford', 'model': 'Mustang', 'year': 2018}

thisdict = {
  "brand": "Ford",
  "model": "Mustang",
  "year": 1964
}
thisdict.update({"year": 2020})
 
print(thisdict)
# {'brand': 'Ford', 'model': 'Mustang', 'year': 2020}