[Python tutorial] 10. Data type - Dictionary

Dictionaries

• key:value pairs
• ordered
• changeable
• do not allow duplicates

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

{'brand': 'Ford', 'model': 'Mustang', 'year': 1964}
Ford

Access Dictionary Items

x = thisdict["model"]
print(x) # Mustang

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

# Get Keys: keys()
x = thisdict.keys() # return list
print(x) # dict_keys(['brand', 'model', 'year'])

# Get Values: values()
x = thisdict.values()
print(x) # dict_values(['Ford', 'Mustang', 1964])

# Get Items: items() as tuples in a list
x = thisdict.items()
print(x) # dict_items([('brand', 'Ford'), ('model', 'Mustang'), ('year', 1964)])

Check if Key Exists: in

if "model" in thisdict:
  print("Yes, 'model' is one of the keys in the thisdict dictionary")

Change Dictionary Items

thisdict["year"] = 2018

# Update Dictionary: update()
thisdict.update({"year": 2020}) # If the item does not exist, the item will be added.

# Add Dictionary Items
thisdict["color"] = "red"

Remove Dictionary Items

# pop()
thisdict.pop("model")

# popitem(): remove last item
thisdict.popitem()

# del: specified key name
del thisdict["model"]
del thisdict # delete the dictionary completely

# clear()
thisdict.clear()
print(thisdict) # {}

Loop Dictionaries

keys

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

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

values

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

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

keys & values

# items(): keys & values
for x, y in thisdict.items():
  print(x, y)

brand Ford
model Mustang
year 1964

Copy Dictionaries

# copy()
mydict = thisdict.copy()

# dict()
mydict = dict(thisdict)

Nested Dictionaries

dictionary can contain dictionaries

# dictionary that contain three dictionaries
myfamily = {
  "child1" : {
    "name" : "Emil",
    "year" : 2004
  },
  "child2" : {
    "name" : "Tobias",
    "year" : 2007
  },
  "child3" : {
    "name" : "Linus",
    "year" : 2011
  }
}
print(myfamily)

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

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

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

print(myfamily)
{'child1': {'name': 'Emil', 'year': 2004}, 'child2': {'name': 'Tobias', 'year': 2007}, 'child3': {'name': 'Linus', 'year': 2011}}