Example 1: dictionary in python
# 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
Example 2: how to create dictionary in python
d = {'key': 'value'}
print(d)
# {'key': 'value'}
d['mynewkey'] = 'mynewvalue'
print(d)
# {'key': 'value', 'mynewkey': 'mynewvalue'}
Example 3: python dictionary access value by key
# Create a list of dictionary
datadict = [{'Name': 'John', 'Age': 38, 'City': 'Boston'},
{'Name': 'Sara', 'Age': 47, 'City': 'Charlotte'},
{'Name': 'Peter', 'Age': 63, 'City': 'London'},
{'Name': 'Cecilia', 'Age': 28, 'City': 'Memphis'}]
# Build a function to access to list of dictionary
def getDictVal(listofdic, name, retrieve):
for item in listofdic:
if item.get('Name')==name:
return item.get(retrieve)
# Use the 'getDictVal' to read the data item
getDictVal(datadict, 'Sara', 'City') # Return 'Charlotte'
# -------------------
# to convert a dataframe to data dictionary
df = pd.DataFrame({'Name': ['John', 'Sara','Peter','Cecilia'],
'Age': [38, 47,63,28],
'City':['Boston', 'Charlotte','London','Memphis']})
datadict = df.to_dict('records')
Example 4: how to get element from dictionary python
#!/usr/bin/python
dict = {'Name': 'Zara', 'Age': 7, 'Class': 'First'}
dict['Age'] = 8; # update existing entry
dict['School'] = "DPS School"; # Add new entry
print "dict['Age']: ", dict['Age']
print "dict['School']: ", dict['School']