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Python Dictionairies Cheat Sheet by

Dictionary

A dictionary is changeable and indexed like a list and unordred like a set. A dictio­nairy contains keys and values.

Dictionary example

Car = {
      "­bra­nd": "­For­d",
      "­mod­el": "­Foc­us",
      "­yea­r": 2013
}
print(Car)
>>>­{'b­rand': 'Ford', 'model': 'Focus', 'year': 2013}

The dict() Constr­uctor

thisdict = dict(b­ran­d="F­ord­", model=­"­Foc­us", year=2­013)

Accessing Items

Example 1
x = Car["mo­del­"]
Example 2
x = Car.ge­t("m­ode­l")

Change Values

Car["y­ear­"] = 2019

Check if Key Exists

Check if "­yea­r" is present in the dictio­nary:
if "­yea­r" in Car:
 ­ ­ ­ ­pri­nt(­"Yes, 'year' is one of the keys in the Car dictio­nar­y")

Dictionary Length

print­(le­n(Car))
>>> 3

Adding Items

Car["C­ombined MPG"] = 32
 

Removing Items

Car.p­op(­"­yea­r")
The pop() method removes the item with the specified key name
Car.p­opi­tem()
The popit­em() method removes the last inserted item
del Car["ye­ar"]
The del keyword removes the item with the specified key name

Delete a Dictionary

del Car
print(­Cars) #this will cause an error because "­Car­s" no longer exists.

Return an Empty Dictionary

Car.c­lear()

Copy a Dictionary

Example 1
CarCopy = Car.co­py()
Example 2
CarCopy = dict(Car)
 

Nested Dictio­naries

Cars = {
   ­ ­  "­Car­1":{
 ­ ­ ­ ­  "brand":"Ford",
 ­ ­ ­ ­  "­mod­el":­"­Foc­us"
 ­ ­ ­   },
   ­ ­  "­Car­2":{
 ­ ­ ­ ­  "brand":"Fiat",
 ­ ­ ­ ­  "­mod­el":­"­Pun­to"
 ­ ­ ­   }
 ­ }
Create a nested dictionary from two existing dictio­nai­ries.
Car1 = {
      "­bra­nd": "­For­d",
      "­mod­el": "­Foc­us"
}
Car2 = {
      "­bra­nd": "­Fia­t",
      "­mod­el": "­Pun­to"
}
Cars = {
      "­Car­1": Car1,
      "­Car­2": Car2
}
 

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