dictionary.py

# Dictionaries are used to store data values in key:value pairs.
# Dictionary items are ordered, changeable, and does not allow duplicates.
# As of Python version 3.7, dictionaries are ordered. In Python 3.6 and earlier, dictionaries are unordered.

# methods

# clear()	Removes all the elements from the dictionary
# copy()	Returns a copy of the dictionary
# fromkeys()	Returns a dictionary with the specified keys and value
# get()	Returns the value of the specified key
# items()	Returns a list containing a tuple for each key value pair
# keys()	Returns a list containing the dictionary's keys
# pop()	Removes the element with the specified key
# popitem()	Removes the last inserted key-value pair
# setdefault()	Returns the value of the specified key. If the key does not exist: insert the key, with the specified value
# update()	Updates the dictionary with the specified key-value pairs
# values()	Returns a list of all the values in the dictionary

# create

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

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

# duplicate values will override
thisdict = {
  "brand": "Ford",
  "model": "Mustang",
  "year": 1964,
  "year": 2020
}
print(thisdict)

# length
print(len(thisdict))

# get item

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

# or

x = thisdict.get("model")
print(x)

# get list of keys
x = thisdict.keys()
print(x)

# add new item to dictionary

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

x = car.keys()

print(x)  # before the change

car["color"] = "white"

print(x)  # after the change

# get values
x = thisdict.values()
print(x)


x = thisdict.items()
print(x)

for y in x:
    print(y)

# key exists
thisdict = {
  "brand": "Ford",
  "model": "Mustang",
  "year": 1964
}
if "model" in thisdict:
    print("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)

# or

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

# remove

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

# remove last item
thisdict = {
  "brand": "Ford",
  "model": "Mustang",
  "year": 1964
}
thisdict.popitem()
print(thisdict)

# or

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

# delete dictionary
thisdict = {
  "brand": "Ford",
  "model": "Mustang",
  "year": 1964
}
del thisdict
# print(thisdict) this will cause an error because "thisdict" no longer exists.

# empty

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

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

# loop keys
for x in thisdict:
    print(x)

# or

for x in thisdict.keys():
    print(x)

# loop values
for x in thisdict:
    print(thisdict[x])

# or

for x in thisdict.values():
    print(x)

# loop keys and values

for x, y in thisdict.items():
    print(x, y)

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

# or

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

# nested

myfamily = {
  "child1": {
    "name": "Emil",
    "year": 2004
  },
  "child2": {
    "name": "Tobias",
    "year": 2007
  },
  "child3": {
    "name": "Linus",
    "year": 2011
  }
}

print(myfamily)

# or

child1 = {
  "name": "Emil",
  "year": 2004
}
child2 = {
  "name": "Tobias",
  "year": 2007
}
child3 = {
  "name": "Linus",
  "year": 2011
}

myfamily = {
  "child1": child1,
  "child2": child2,
  "child3": child3
}

print(myfamily)