Create les9_dictionaries.py

Dictionaries

Author: alva922

Diff for: les9_dictionaries.py

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+#https://newdigitals.org/2024/01/23/basic-python-programming/#dictionaries
+#Dictionaries are used to store data values in key: value pairs.
+#A dictionary is a collection which is ordered (as of Python version 3.7), changeable and do not allow duplicates.
+#Dictionaries are written with curly brackets, and have keys and values:
+thisdict = {
+  "brand": "Ford",
+  "model": "Mustang",
+  "year": 1964
+}
+print(thisdict)
+Output:
+{'brand': 'Ford', 'model': 'Mustang', 'year': 1964}
+#It is possible to use the dict() constructor to make a dictionary
+thisdict = dict(name = "John", age = 36, country = "Norway")
+print(thisdict)
+Output:
+{'name': 'John', 'age': 36, 'country': 'Norway'}
+#You can access the items of a dictionary by referring to its key name, inside square brackets
+thisdict = {
+  "brand": "Ford",
+  "model": "Mustang",
+  "year": 1964
+}
+x = thisdict["model"]
+print (x)
+Output:
+Mustang
+#The keys() method will return a list of all the keys in the dictionary
+x = thisdict.keys()
+print (x)
+Output:
+dict_keys(['brand', 'model', 'year'])
+#The values() method will return a list of all the values in the dictionary
+x = thisdict.values()
+print (x)
+Output:
+dict_values(['Ford', 'Mustang', 1964])
+#Make a change in the original dictionary, and see that the values list gets updated as well
+car = {
+"brand": "Ford",
+"model": "Mustang",
+"year": 1964
+}
+ 
+x = car.values()
+ 
+print(x) #before the change
+ 
+car["year"] = 2020
+ 
+print(x) #after the change
+ 
+Output:
+dict_values(['Ford', 'Mustang', 1964])
+dict_values(['Ford', 'Mustang', 2020])
+#Check if “model” is present in the dictionary
+thisdict = {
+  "brand": "Ford",
+  "model": "Mustang",
+  "year": 1964
+}
+if "model" in thisdict:
+  print("Yes, 'model' is one of the keys in the thisdict dictionary")
+Output:
+Yes, 'model' is one of the keys in the thisdict dictionary
+#The update() method will update the dictionary with the items from the given argument
+thisdict = {
+  "brand": "Ford",
+  "model": "Mustang",
+  "year": 1964
+}
+thisdict.update({"year": 2020})
+print (thisdict)
+Output:
+{'brand': 'Ford', 'model': 'Mustang', 'year': 2020}
+#Adding an item to the dictionary is done by using a new index key and assigning a value to it
+thisdict = {
+  "brand": "Ford",
+  "model": "Mustang",
+  "year": 1964
+}
+thisdict["color"] = "red"
+print(thisdict)
+Output:
+{'brand': 'Ford', 'model': 'Mustang', 'year': 1964, 'color': 'red'}
+#The pop() method removes the item with the specified key name:
+thisdict = {
+  "brand": "Ford",
+  "model": "Mustang",
+  "year": 1964
+}
+thisdict.pop("model")
+print(thisdict)
+Output:
+{'brand': 'Ford', 'year': 1964}
+#The clear() method empties the dictionary:
+thisdict = {
+  "brand": "Ford",
+  "model": "Mustang",
+  "year": 1964
+}
+thisdict.clear()
+print(thisdict)
+Output:
+{}
+#Make a copy of a dictionary with the copy() method:
+thisdict = {
+  "brand": "Ford",
+  "model": "Mustang",
+  "year": 1964
+}
+mydict = thisdict.copy()
+print(mydict)
+Output:
+{'brand': 'Ford', 'model': 'Mustang', 'year': 1964}
+#Add Items to a Python Dictionary with Different Data Types
+Dict = {}
+print("Empty Dictionary: ")
+print(Dict)
+Dict[0] = 'Go'
+Dict[2] = 'For'
+Dict[3] = 1
+print("\nDictionary after adding 3 elements: ")
+print(Dict)
+ 
+Dict['Value_set'] = 2, 3, 4
+print("\nDictionary after adding 3 elements: ")
+print(Dict)
+ 
+Dict[2] = 'Welcome'
+print("\nUpdated key value: ")
+print(Dict)
+Dict[5] = {'Nested': {'1': 'Life', '2': 'Python'}}
+print("\nAdding a Nested Key: ")
+print(Dict)
+ 
+Output:
+Empty Dictionary: 
+{}
+ 
+Dictionary after adding 3 elements: 
+{0: 'Go', 2: 'For', 3: 1}
+ 
+Dictionary after adding 3 elements: 
+{0: 'Go', 2: 'For', 3: 1, 'Value_set': (2, 3, 4)}
+ 
+Updated key value: 
+{0: 'Go', 2: 'Welcome', 3: 1, 'Value_set': (2, 3, 4)}
+ 
+Adding a Nested Key: 
+{0: 'Go', 2: 'Welcome', 3: 1, 'Value_set': (2, 3, 4), 5: {'Nested': {'1': 'Life', '2': 'Python'}}}
+#Dictionary Methods: clear, copy, fromkeys, get, items, keys, pop, popitem, setdefault, update, and values.