# Order of operators matters
4 * 5 - 12

# Simple Division returns a float
(3 + 9) / 4 

# Floor Division disregards the fractional part
13 // 5

# Geeting the remainder of a division
13 % 5

# Power of a number
2 ** 4

# Variable assigment
a = 3
b = 4
h = (a**2 + b**2)**(1/2)
h

# Comparison
1 > 5

# Comparison
1 < 8

# Comparison
1 <= 1

# Comparison
8 == 8

# Comparison
'by' == 'goodbye'

# Operator: and
a = 10
a > 5 and a < 20

# Operator: or
a = 10
a >= 5 or a < 8

# Operator: not
a = 10
not (a < 5)

# String handling
str1 = 'Hello'
str2 = " variable 'x'"
str3 = " and variable \'y\'"
str4 = str1 + str2 + str3
str4

# \n causes a new line
str = 'First line.\nSecond line.'
print(str)

# Indexing strings
word = "Python"
word[0]

# Slicing Strings: Characters from position 1 to position 2, position 3 is excluded
word[1:3] 

# Characters from position 2 to the end
word[2:] 

# Length of a string
len(word)

# List of Integers
primes = [1, 2, 3, 5, 7]
primes

# Indexing returns an element
primes[-1]

# Slicing returns a new list
primes[:3]

# Concatenation
primes + [11,13,17]

# Slice assignation
letters = ['a', 'b', 'c', 'd', 'e', 'f', 'g']
letters[2:5] = []
letters

# Length of a List
len(letters)

# List from a String
letters = list('PYTHON')
letters

# Check if element is in a list
letters = list('PYTHON')
'P' in letters

# Get index of a element in a list
fruits = list(['orange', 'apple', 'banana', 'grapes'])
fruits.index('banana')

x = int(input("Please enter an integer: "))
# if is the minimal required statement
if x < 0:
    x = 0
    print('Negative changed to zero')
elif x == 0:
    print('Zero')
elif x == 1:
    print('Single')
else:
    print('More')

# Conditional assignment
grade = 9
result = 'A' if grade > 9 else 'B'
result

# Obtain the length of some strings:
words = ['Python', 'Java', 'Pascal']
# use 'for' to iterate a list
for w in words:
    print(w, '->', len(w))

for i in range(5):
    print(i**2)

i = 1
while i <= 3 :
    print('i is: {}'.format(i))
    i = i + 1

for i in [1,2,3]:
    pass  # Does nothing

# range() defines an iterable, in this case of 4 values
for i in range(4):
    print(i)

# range() can start at another number
for j in range(5,10):
    print(j)

# range() returns an object(iterable) which returns the successive items of 
# the desired sequence when you iterate over it
r = range(0, 10, 3)
r

# The function list() creates lists from iterables
list(r)

# The keyword def introduces a function definition.
def square(n): # Calculates the square of a number n
    return n ** 2

# Calling our square function
square(3)

# Assigning the function to a variable and calling that
sq = square
sq(4)

# Default argument value
def repeatPrint(message, times=5, finalMsg='Bye'):
    i = 1
    while i <= times:
        i += 1
        print(message)
    print(finalMsg)

    

# Calling the function with all arguments
repeatPrint('Hello', 2, 'Good bye')

# Calling the function without optinal argument
repeatPrint('Hello')

# Using keyword Arguments
repeatPrint(times=3, message='Hi', finalMsg='HoHoHo')

# Keywords and arguments
def cheeseshop(kind, *arguments, **keywords):
    print("-- Do you have any", kind, "?")
    print("-- I'm sorry, we're all out of", kind)
    for arg in arguments:
        print(arg)
    print("-" * 40)
    for kw in keywords:
        print(kw, ":", keywords[kw])
# 
# Calling the defined function
cheeseshop("Limburger", "It's very runny, sir.",
           "It's really very, VERY runny, sir.",
           shopkeeper="Michael Palin",
           client="John Cleese",
           sketch="Cheese Shop Sketch")

# Unpacking Argument Lists
list(range(3, 6))  # normal call with separate arguments
args = [3, 6]      # List 
list(range(*args))  # call with arguments unpacked from a list

# Documentation of Functions
def myFunction():
    """Do nothing, but document it.
    
    No, really, it doesn't do anything.
        """
    pass
#
print(myFunction.__doc__)

# Define the lambda expression
def any_exp(n):
    return lambda x: x**n

# Call the lambda expression
cubic = any_exp(3)
cubic(4)

# Defining a tuple with heterogenous data
t = 12345, 54321, 'hello!'
t[0]  # 12345
t

# Tuples may be nested:
u = t, (1, 2, 3, 4, 5)
u
# Tuples are immutable:
# t[0] = 100 # yields error

# Tuples enclosed in parentheses
customer = (1234, 'Texas', 'Male')
customer

# zip() used to generate an iterator of tuples
# returns a zip object that is an iterator of tuples
a = [1, 2, 3]
b = [4, 5, 6]
c = zip(a, b)
for t in c:
    print(t)

# Duplicates are removed
countries = {'Peru', 'Mexico', 'Chile', 'Peru', 'Canada', 'Chile'}
countries

# Membershing validation
'Peru' in countries

# set() can be used to create sets
set_let = set('tennessee')
set_let

# Defining a dictionary
tel = {'jack': 4098, 'sape': 4139}
tel['guido'] = 4127
tel

# Accesing a value
tel['jack']

# Delete a key-value
del tel['sape']
tel

## Adding a key-value
tel['irv'] = 4127
tel

# List the keys
list(tel)

# Sort the list of keys
sorted(tel)

# Validate the existance of a key
'guido' in tel

# Construct a dictionary from key-pair value
dict(sape=4139, guido=4127, jack=4098)

# Print supports multiparameters
pi = 3.1416
print('The value of pi is:', pi)

# Print with format
num = '123';
name = 'Jhon'
print('My number is: {a}, and my name is: {b}'.format(a=num,b=name))

# Type of an object
l = list('UTIL');
type(l)

# Help/Documentation
len?

# Set a O.S. directory path
import os
datapath = os.path.join("datasets", "islr", "")

# Capture the enlapsed time of a task
import time
tic = time.time();
time.sleep(2)
toc = time.time();
print('The enlapsed time was: ' + str(toc - tic) + " seg")