python dictionary and

#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)])

python dict

# decleration
my_dict = {
  'spam': 'eggs',
  'foo': 4,
  100: 'bar',
  2: 0.5
}

# access single values from the dictionary
print(my_dict['spam']) # eggs
print(my_dict['foo']) # 4
print(my_dict[100]) # bar
print(my_dict[2]) # 0.5

# iterate over the dictionary
for key, value in my_dict.items():
  print(key, value)

# get length of the dictionary
print(len(my_dict)) # 4

# modify the dictionary
my_dict['baz'] = 'qux' # adds a pair
my_dict['baz'] = 'quxx' # also updates it
del my_dict['spam'] # removes a pair

# other methods
print(my_dict.copy()) # Returns a copy of the dictionary
print(my_dict.fromkeys('added', 100)) # Returns a dictionary with the specified keys and their values
print(my_dict.get('foo')) # Returns the value of the specified key
print(my_dict.items()) # Returns a list containing a tuple for each key value pair
print(my_dict.keys()) # Returns a list containing the dictionaries keys
print(my_dict.values()) # Returns a list of all the values in the dictionary
my_dict.setdefault('a', 'b') # Returns the value of the specified key. If the key does not exist: insert the key, with the specified value
my_dict.pop('foo') # Removes the element with the specified key
my_dict.popitem() # Removes the last inserted key-value pair
my_dict.update({'baz': 'val'}) # Updates the dictionary with the specified key-value pairs
my_dict.clear() # Removes all the elements from the dictionary

Posted by: Guest on June-05-2020

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