Python Cheat Sheet Part - 3

Dictionaries
The dictionary is an unordered set of comma-separated key:value pairs, within {}, with the requirement that within a dictionary, no two keys can be the same.

Dictionary

<dictionary-name> = {<key>: value, <key>: value ...}

Adding Element to a dictionary
By this method, one can add new elements to the dictionary

<dictionary>[<key>] = <value>

Updating Element in a dictionary
If a specified key already exists, then its value will get updated

<dictionary>[<key>] = <value>

Deleting an element from a dictionary
del keyword is used to delete a specified key:value pair from the dictionary as follows:

del <dictionary>[<key>]

Dictionary Functions & Methods
Below are some of the methods of dictionaries

len() method
It returns the length of the dictionary, i.e., the count of elements (key: value pairs) in the dictionary

len(dictionary)

clear() method
Removes all the elements from the dictionary

dictionary.clear()

**get() method
**Returns the value of the specified key

dictionary.get(keyname)

items() method
Returns a list containing a tuple for each key-value pair

dictionary.items()

keys() method
Returns a list containing the dictionary's keys

dictionary.keys()

values() method
Returns a list of all the values in the dictionary

dictionary.values()

update() method
Updates the dictionary with the specified key-value pairs

dictionary.update(iterable)

Conditional Statements
The if, elif and else statements are the conditional statements in Python, and these implement selection constructs (decision constructs).

if Statement

if(conditional expression):
    statements

if-else Statement

if(conditional expression):
    statements
else:
    statements

if-elif Statement

if (conditional expression):
    statements
elif (conditional expression):
    statements
else:
    statements

Nested if-else Statement

if (conditional expression):
    if (conditional expression):
        statements
    else:
        statements
else:
    statements

Loops in Python
A loop or iteration statement repeatedly executes a statement, known as the loop body, until the controlling expression is false (0).

For Loop
The for loop of Python is designed to process the items of any sequence, such as a list or a string, one by one.

for <variable> in <sequence>:
    statements_to_repeat

While Loop
A while loop is a conditional loop that will repeat the instructions within itself as long as a conditional remains true.

while <logical-expression>:
    loop-body

Break Statement
The break statement enables a program to skip over a part of the code. A break statement terminates the very loop it lies within.

for <var> in <sequence>:
    statement1
    if <condition>:
        break
    statement2
statement_after_loop

Continue Statement
The continue statement skips the rest of the loop statements and causes the next iteration to occur.

for <var> in <sequence>:
    statement1
    if <condition> :
        continue
    statement2
    statement3
    statement4

Functions
A function is a block of code that performs a specific task. You can pass parameters into a function. It helps us to make our code more organized and manageable.

Function Definition
def my_function(parameters):
    pass #statements

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