Python Study

conditional_statements.py

# if 
if True:
	print(" It's condition is True ")

# if-else
if False:
	print(" It's condition is True ")
else:
	print(" It's condition is False ")

# if-elseif-else
x = 10
if x<0:
	print(" x is smaller than 0 ")
elif x==10:
	print(" x is 10 ")
else:
	print(" x is nothing else")

# and, or
if x > 0 and x < 20:
	print(" x is larger than 0 and smaller than 20 ")

if x > 0 or x < 10:
	print(" x is not smaller than 10, but x is larger than 0, So it is true statement. ")

# double if
if x > 0:
	print("x is larger than 0!")
	if x < 10:
		print("x < 10 is true!")
	else:
		print("x < 10 is not true!")
print("after double if")

controlflow.py

birthyear = 1983
running = True

# while
while running:
	guess = int(input("Guess Jintae's birth year : "))
	if guess == birthyear:
		running = False
	elif guess > birthyear:
		print("Thank you... but it's less than mine.")
	elif guess < birthyear:
		print("I'm not old like that.")

else:
	print("That's right!")

print("done")

# for .. in
for x in range(1,10):
	print("Count {}".format(x))
	if x == 5:
		break
		# see what hanppens when break encountered.
else:
	print("for loop is over!")
	# when break encountered, this doesn't work.


# continue, break
while True:
	keyword = input("input something : ")
	if keyword == "exit" or keyword == "quit":
		break
	if len(keyword) < 4:
		print("Too small!")
		continue
print("done")

data_structure_list.py

# list
wishlist = [ "PS4 Pro", "Candy Red Colored Mustang Guitar", "Old BMW Car" ]

print( len(wishlist), "items in 'wishlist' " )


# show list
def printItems():
	idx = 0
	print( "Items are : ", end=' ' )
	for item in wishlist:
		idx = idx + 1
		if idx < len(wishlist):
			print( item, end=', ' )
		else:
			print( item )

printItems()

# append
wishlist.append("MacBook Pro New Model w/TouchBar")
print( "Also I want to have :", wishlist[len(wishlist)-1] )

print( "\nNow, All the items in wishlist are like above" )
print( "-------------------" )
printItems()

# sort
print("\nAnd, I will sort my items, default is by alphabet asc")
print( "-------------------" )
wishlist.sort()
printItems()

# sort reverse
print("\nReversed Sort")
print( "-------------------" )
wishlist.sort(reverse=True)
printItems()

# get item by index
print("\nFirst Item is :", wishlist[0])
print("Last Item is :", wishlist[len(wishlist)-1])

# delete item
print("I don't need Last item right now. I'll need it later...")
del wishlist[ len(wishlist)-1 ] # delete last item, Candy Red Mustang Guitar (because it sorted)
print("Now, ", end=' ')
printItems()

# define search and delete function
def searchAndDelete(keyword):
	idx = 0
	foundItem = 0
	for item in wishlist:
		if item.find(keyword) > -1:
			foundItem = foundItem + 1
			print( "found \"", item, "\" and I will delete it..." )
			del wishlist[idx]
		idx = idx + 1
	return foundItem

# I referenced 'find' method in link above :
# https://www.tutorialspoint.com/python/string_find.htm

# search and delete
print( "find 'BMW' in wishlist and delete..." )
print( searchAndDelete('BMW'), "items found and deleted" )
print( "Now my wishlist is " )
printItems()

functions.py

# regular function
def say_hello():
	print("Hello World")

# local variable
x = 10
def check_x(x):
	print("x is ", x)
	x = 1
	print("now x is ", x)

check_x(x)
print('x is still', x)


# use global variable
def use_global():
	global x
	x = 5
	print("now x is", x)

use_global()
print('x is now', x)


# return value
def func_add(x, y):
	return x+y

print("1 + 5 = ", func_add(1, 5))


# default value
def use_default(x=10):
	if x==10:
		print("x is default value")
	else:
		print("x is not default value")

use_default()
use_default(5)


# keyword argument
def keyarg(a=0, b=1, c=2):
	print("a :",a," b :",b," c :",c)

keyarg()
keyarg(a=10, c=10)
keyarg(c=50, a=20)


# VarArgs Parameters
def VarArgsFunc(*numbers, **emails):
	'''It takes numbers and print sum of numbers

	And takes dictionary of names and emails and print it.'''

	# print sum of numbers
	sum_of_numbers = 0
	for x in numbers:
		sum_of_numbers += x
	print("Sum of numbers is :", sum_of_numbers)

	# print emails
	for name, email in emails.items():
		print(name, "'s email address is :",email)

VarArgsFunc(1,2,3,4,5,6,7,8,9,10,Jintae="jtjoo@me.com",Johnny="john@python.com",Ian="ianjoo@python3.com")

print(VarArgsFunc.__doc__)

# print function documents and description about parameters with less
help(VarArgsFunc)

search.py

# Name search
file = open("names")
print("\n\nName Search Result")
print("----------------------")
for line in file:
	if line.startswith("John"):
		print(line)

# Email Search
file = open("names")
print("\n\nEmail Search Result")
print("----------------------")
for line in file:
	# if line.startswith("John"):
	name, email = line.split(",")
	if name == "John Joo":
		print(email)

################################### 
# Contents of file "names"  
###################################
# 
# John Denver,johndenver@gmail.com
# Jintae Joo,jintaejoo@gmail.com
# Ian Curtis,iancurtis@gmail.com
# Ian Johnnas,ianjohnnas@gmail.com
# Johnathan Davis,johnathandavis@gmail.com
# John Joo,johnjoo@gmail.com
# John Lee Joo,johnjoo@gmail.com
# John Hammerstein,johnhammerstein@gmail.com
# Thomas Lee,thomaslee@gmail.com
# Siyeon Lee,siyeonlee@gmail.com

strings_and_numbers.py

# Quotes (single, double)
print('Hello')
print("Hello")

# Triple Quotes
print('''
	Hi, This is Jintae
	I am learning python
	to rebuild my old event sources.
''')

# Calculate Strings
print('Hello' + " World")
print("Hello 'World'")
print('Hello' * 3)

# Print by Position
print('Hello'[0])
print('Hello'[1])
print('Hello'[4])

print("Hello"[3])
print("Hello"[0])

# Functions in String Object
print("hello world".capitalize())
print("hello world".upper())
print("HELLO WORLD".lower())
print("hello world".__len__())
print(len("hello world"))
print('hello world'.replace( 'world', 'jintae' ))

# Format Method
name = "jintae"
email = "jtjoo@me.com"
birthyear = 1983
print( " {0}'s E-mail address is {1}, born in {2} ".format( name, email, birthyear ) )

# Special Characters
print("jintae's \"Tutorial\"")
print("\\")
print("Hello\nworld")
print("Hello\tworld")
print("\a\b")

# Numbers and String
print(10+5)
print("10"+"5")