python dictionary definition code example

Example 1: python dictionary

#Creating dictionaries
dict1 = {'color': 'blue', 'shape': 'square', 'volume':40}
dict2 = {'color': 'red', 'edges': 4, 'perimeter':15}

#Creating new pairs and updating old ones
dict1['area'] = 25 #{'color': 'blue', 'shape': 'square', 'volume': 40, 'area': 25}
dict2['perimeter'] = 20 #{'color': 'red', 'edges': 4, 'perimeter': 20}

#Accessing values through keys
print(dict1['shape'])

#You can also use get, which doesn't cause an exception when the key is not found
dict1.get('false_key') #returns None
dict1.get('false_key', "key not found") #returns the custom message that you wrote 

#Deleting pairs
dict1.pop('volume')

#Merging two dictionaries
dict1.update(dict2) #if a key exists in both, it takes the value of the second dict
dict1 #{'color': 'red', 'shape': 'square', 'area': 25, 'edges': 4, 'perimeter': 20}

#Getting only the values, keys or both (can be used in loops)
dict1.values() #dict_values(['red', 'square', 25, 4, 20])
dict1.keys() #dict_keys(['color', 'shape', 'area', 'edges', 'perimeter'])
dict1.items() 
#dict_items([('color', 'red'), ('shape', 'square'), ('area', 25), ('edges', 4), ('perimeter', 20)])

Example 2: dictionary in python

# Dictionaries in Python

ages = {"John": 43, "Bob": 24, "Ruth": 76} # Marked by { at beginning and a } at end

# ^^^ Has sets of keys and values, like the 'John' and 43 set. These two values must be seperated by a colon

# ^^^ Sets of values seperated by commas.

Example 3: dictionary in python

my_dict = {"key": "value", "a": 1, 2: "b"}
print(my_dict["key"])
# Output: value
print(my_dict["a"])
# Output: 1
print(my_dict[2])
# Output: b

Example 4: def dict(d)

def dict(d)

Example 5: dictionary in python

A dictionary in python is in all a list that holds 1 value for 1 key and as you 
add more values you have to add more keys.