xxxxxxxxxx
#Python dictionaries consists of key value pairs tha
#The following is an example of dictionary
state_capitals = {
'Arkansas': 'Little Rock',
'Colorado': 'Denver',
'California': 'Sacramento',
'Georgia': 'Atlanta'
}
#Adding items to dictionary
#Modification of the dictionary can be done in similar maner
state_capitals['Kampala'] = 'Uganda' #Kampala is the key and Uganda is the value
#Interating over a python dictionary
for k in state_capitals.keys():
print('{} is the capital of {}'.format(state_capitals[k], k))
xxxxxxxxxx
#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)])
xxxxxxxxxx
#title :Dictionary Example
#author :Josh Cogburn
#date :20191127
#github :https://github.com/josh-cogburn
#====================================================
thisdict = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}
#Assigning a value
thisdict["year"] = 2018
xxxxxxxxxx
student_data = {
"name":"inderpaal",
"age":21,
"course":['Bsc', 'Computer Science']
}
#the keys are the left hand side and the values are the right hand side
#to print data you do print(name_of_dictionary['key_name'])
print(student_data['name']) # will print 'inderpaal'
print(student_data['age']) # will print 21
print(student_data['course'])[0]
#this will print 'Bsc' since that field is an array and array[0] is 'Bsc'
xxxxxxxxxx
dict = {"apple": "fruit", "ball": "object", "cricket": "sports"}
#how to print?
print(dict["cricket"])
xxxxxxxxxx
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
xxxxxxxxxx
# Dictionaries in Python are used to store set of data like Key: Value pair
# the syntax of a dictionary in Python is very simple we use {} inside that
# we define {Key: Value}, to separate multiple values we use','
programming_dictionary = {
"Bug": "An error in a program that prevents the program from running as expected.",
"Function": "A piece of code that you can easily call over and over again.",
"Loop": "The action of doing sommething again and again",
}
# to retrieve the values from a dictionary we use the Key name as an Index
# retrieving the Function's definition
print(programming_dictionary["Function"]) # this will print the definition of Function
# if you wanna print all the entries in the dictionary you can do that by for loop
for key in programming_dictionary:
print(programming_dictionary[key]) # prints all entries
# adding items to a dictionary
# the following code will add another entry to the dictionary called Variable
programming_dictionary["Variable"] = "The label to store some sort of data"
print(programming_dictionary["Variable"])
# editing the values of a key
# editing the value of variable
programming_dictionary["Variable"] = "Variables are nothing but reserved memory locations to store values. This means that when you create a variableyou reserve some space in memory"
# if you learnt something from this please upvote it
xxxxxxxxxx
x = dict(name = "vvy", age = 17, country = "India")
print(x)
# {'name': 'vvy', 'age': 17, 'country': 'India'}
xxxxxxxxxx
#A dictionary has key-value pairs. Here 1,2,3 are the keys and Item1,Item2,Item3
#are their values respectively.
dictionaryName = { 1: "Item1", 2: "Item2", 3: "Item3"}
#retrieving value of a particular key
dictionaryName[1]
#retrieving all the keys in a dictionary
dictionaryName.keys()
#retrieving all the values in a dictionary
dictionaryName.values()
xxxxxxxxxx
# 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.
xxxxxxxxxx
# dictionary refresh
new_dict = {
"first":"1,2,3",
"second":"321",
"third":"000",
}
# adding to dictionary
new_dict.update({"fourth":"D"})
print(new_dict)
#removing from dictionary
new_dict.pop("first")
print(new_dict)
new = {"five":"888"}
#updating a dictionary
new_dict.update(new)
print(new_dict)