Python Dictionairies Cheat Sheet

A Programming › Python cheat sheet in English by Nouha_Thabet

Python Programming

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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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