
print('hello world')

hello world


%%R
install.packages('blogdown')
library(blogdown)


print("hello world" + "!")


print("welcome", "to", "python", sep="_", end=";")


print("welcome", "to", "python", sep="_", end=";")
print("data science")


print("welcome", "to", "python", sep="_", end="\n") # end with new line(by default)
print("data science")


# this statement will print the statement inside in it
print("welcome to data science")


t = True


type(t)


False


i = 4 
type(i)


f = 3.45 
type(f)


cmp = 3+4j
type(cmp)


cmp.real


cmp.imag


1 + 1


1 * 3


1 / 2


print(7+8)
print(4*6)
2 ** 4


4 % 2


5 % 2


(2 + 3) * (5 + 5)


3+3/3


(3+3)/3


((((13+5)*2)-4)/2)-13
# How did that happen? Let’s work it out.
# 13+5 gives us 18
# 18*2 gives us 36
# 36-4 gives us 32
# 32/2 gives us 16.0 #Note that division gives us floats!
# 16-13 gives us 3.0


st = 'data science and machine learning with python'


type(st)


# positive indexing
print(st[0])
print(st[1])
print(st[2])


# negative indexing
print(st[-1])
print(st[-2])
print(st[-3])


print(st[0:4])
print(st[:4])
print(st[4:])
print(st[5:9])
print(st[::2]) # step 2
print(st[::3]) # step 2
print(st[2:12:4]) # 
print(st[::-1])  # reverse the string
print(st[::-2])  # reverse the string with step 1


s= "hello world" # using double quotes


s= 'hello world' # using single quotes


# Multi-line Strings
to_you = """Stranger, if you passing meet me and desire to speak to me, why
  should you not speak to me?
And why should I not speak to you?"""

print(to_you)


s.index('d')


s.capitalize()


s.count('o')


value = "cat ppicture is cat picture"

# Find first index of this string.
i = value.find("p")
print(i)

# Find first index (of this string) after previous index.
b = value.find("p", i + 1)
print(b)


b = value.find("p", i + 2)
print(b)


s.title()


s.upper()


s.islower()


s= "HELLO WORLD"


s.islower()


s.capitalize()


s.lower()


s = "HeLlO WoRlD"


s.swapcase()


s = " Hello world how are you "


s = "hello world how are you"


s.capitalize()


s.title()


s.upper()


"H" in s


"h" in s


len(s)


s = ' hello world how are you'


s.strip()


min(s.strip())


max(s)

s


s.isspace()


s.strip()


greeting = 'Hello, world!'
new_greeting = 'J' + greeting[1:]
print(new_greeting)
print(greeting)


name = "sumendar"
greeting = "My name is {}".format(name)
greeting


print("happy" + " " + "birthday")
print("my name is " + "john")


print('This string contains a single quote (') character.')
# gives a syntaxError


print('This string contains a single quote (\') character.')
print("This string contains a double quote (\") character.")


print('a,
      b,
      c)    # if we press Enter will gives SyntaxError after each letter


print('a\
b\
c')

print('a\
b\
c')


print('foo\\bar') # o include a literal backslash in a string, escape it with a backslash


print(r'foo\bar') # o include a literal backslash in a string, escape it with a letter r


print('foo\tbar')
print("a\tb")
print("a\141\x61")
print("a\nb")
print('\u2192 \N{rightwards arrow}')


print('foo\nbar')


print(r'foo\nbar')


print('foo\\bar')


print(r'foo\\bar')


print('''This string has a single (') and a double (") quote.''')


print("""This is a
string that spans
across several lines""")
# this also allows for multiline strings:


import datetime

x = datetime.datetime.now()
print(x)


print(x.year)


# strftime is a method for formatting date objects into readable strings.
print(x.strftime("%A"))
# it takes one parameter called format
# http://strftime.org/


# Create a date object
x = datetime.datetime(2020, 5, 17)
print(x)


[1,2,3]


['hi',1,[1,2]]


my_list = ['a','b','c']


my_list.append('d')


my_list


my_list[0]


my_list[1]


my_list[1:]


my_list[:1]


my_list[0] = 'NEW'


my_list


mylist = ['Rhino', 'Grasshopper', 'Flamingo', 'Bongo']
B = len(mylist) # This will return the length of the list which is 3. The index is 0, 1, 2, 3.
print (mylist[1]) # This will return the value at index 1, which is 'Grasshopper'
print (mylist[0:2]) # This will return the first 2 elements in the list.


nest = [1,2,3,[4,5,['target']]]


nest[3]


nest[3][2]


nest[3][2][0]


# assign data to a specific element of the list using an index into the list.
mylist = [0, 1, 2, 3]
mylist[0] = 'Rhino'
mylist[1] = 'Grasshopper'
mylist[2] = 'Flamingo'
mylist[3] = 'Bongo'
print (mylist[1])


a = [1, 2, 3]
b = [4, 5, 6]
c = a + b  # 
print(c)


 
[0] * 4


[1, 2, 3] * 3  # The first example repeats [0] four times. The second example repeats the list [1, 2, 3] three times.


a = 'banana'
b = 'banana'
a is b


a = [1, 2, 3]
b = [1, 2, 3]
a is b


l = [1,2,3,4,5]
l[::-1] # reverse the order of list


x = [True, True, False]
if any(x):
    print("At least one True")
if all(x):
    print("Not one False")
if any(x) and not all(x):    
    print("At least one True and one False")


l1 = [1,2,3,4]
l2 = l1
print(id(l1))
print(id(l2))


l1.append(999)
print(l2)


l1 = [1,2,3,4]
l2 = l1.copy()
print(id(l1))
print(id(l2))


l1.append(999)
print(l2)


t = (1,2,3)


# real world example
# works better in spyder tool
""" Where's My Mouse? """
import tkinter

def mouse_click(event):

    # retrieve XY coords as a tuple
    coords = root.winfo_pointerxy()
    print('coords: {}'.format(coords))
    print('X: {}'.format(coords[0]))
    print('Y: {}'.format(coords[1]))
    print(type(coords))

root = tkinter.Tk()
root.bind('<Button>', mouse_click)
root.mainloop()


room_num = {'john': 425, 'tom': 212}
room_num['john'] = 645  # set the value associated with the 'john' key to 645


print(room_num)


room_num['james'] = 925


print(room_num)


room_num.keys()


room_num.values()


room_num.items()


room_num.pop('james') # takes key as parameter and return corresponding value


room_num


room_num.popitem() # doesn't take any parameter and gives some arbitrary element as (key, value) tuple


room_num


room_num['isaac'] = 345 # Add a new key 'isaac' with the associated value
print (room_num.keys()) # print out a list of keys in the dictionary
print ('isaac' in room_num) # test to asee if 'issac' is in the dictionary.  This returns true.


d = {'key1':'value1','key2':'value2'}

d


d['key1']


{1,2,3}


# creating a set
a = {1, 3, 5, 7, 11, 13}
b = set([1, 3, 5, 7, 11, 13])


# Union
A = {1, 2, 3, 4}
B = {3, 4, 5, 6}
print ( A | B)


# Intersection
A = {1, 2, 3, 4}
B = {3, 4, 5, 6}
print ( A & B )


# Difference
A = {1, 2, 3, 4, 5}
B = {4, 5, 6, 7, 8}
print(A - B)


# Symmetric Difference
A = {1, 2, 3, 4, 5}
B = {4, 5, 6, 7, 8}
print(A ^ B)


a.add(8)
print(a)
b.update([5,2,14,7])
print(b)


# initialize my_set
my_set = {1,3}
print(my_set)

# add list and set
# Output: {1, 2, 3, 4, 5, 6, 8}
my_set.update([4,5], {1,6,8})
print(my_set)

# if you uncomment below line
# you will get an error
# TypeError: 'set' object does not support indexing

#my_set[0]


num = {13,12,21,43,16,25}


num.discard(3)

num


num.remove(5)

num


num = {13,12,21,43,16,25}


num.pop()


num = {13,12,21,43,16,25}


num.clear()

num


S = frozenset([1,2,3])
print(S)


""" A Queue of Groceries to Put Away """
# queue is a not built-in datatype
# create a new queue object
import queue 
q = queue.Queue() # create a new object by calling new Queue() custroctor
print(q.empty())

# put bags into the queue
q.put('bag1')
print(q.empty())
q.put('bag2')
q.put('bag3')

# get bags from the queue in FIFO order
print(q.get())
print(q.get())
print(q.get())
# q.get() # causes an error: blocking method, the program will wait until method completes before continuiing execution
# (restart the shell) 

# create a new queue to hold two items
q = queue.Queue(2)
print(q.empty())

# put two bags into the two-item queue
q.put('bag1')
print(q.full())
q.put('bag2')
print(q.full())

# try to put an extra bag into the queue
q.put_nowait('bag3') # causes an error


""" A Stack of Bills to Pay """
# python doesn't has built-n stack module, we can use list instead
# create a list to use as the stack
stack = list()

# add some bills to the stack
stack.append('bill1')
stack.append('bill2')

# remove the top bill to pay it
print(stack.pop())

# add two more bills to the stack
stack.append('bill3')
stack.append('bill4')

# remove bills from top to bottom
print(stack.pop())
print(stack.pop())
print(stack.pop())
stack.pop() # causes Indexerror exception


int1 = 4
float1 = int1 + 2.1 # 4 converted to float
# str1 = "My int:" + int1 # Error: no implicit type conversion from int to string
int2 = 4 + True # 5: bool is implicitly converted to int


int1 = 8
str1 = str(int1)
str2 = "My int:" + str1
print(str2)
v1 = int(2.7) # 2
v2 = int(-3.9) # -3
v3 = int("2") # 2
v4 = int("11", 16) # 17, base 16
# v5 = long(2) # this supports only in python 2 vesion
v6 = float(2) # 2.0
v7 = float("2.7") # 2.7
v8 = float("2.7E-2") # 0.027
v9 = float(False) # 0.0
vA = float(True) # 1.0
vB = str(4.5) # "4.5"
vC = str([1, 3, 5]) # "[1, 3, 5]"
vD = bool(0) # False; bool fn since Python 2.2.1
vE = bool(3) # True
vF = bool([]) # False - empty list
vG = bool([False]) # True - non-empty list
vH = bool({}) # False - empty dict; same for empty tuple
vI = bool("") # False - empty string
vJ = bool(" ") # True - non-empty string
vK = bool(None) # False
vL = bool(len) # True
vM = set([1, 2])
vN = list(vM)
vO = list({1: "a", 2: "b"}) # dict -> list of keys
vP = tuple(vN)
vQ = list("abc") # ['a', 'b', 'c']
print (v1, v2, v3, type(v1), type(v2), type(v3))

Operators (Decreasing order of precedence)	Operators (Decreasing order of precedence)
`**`	Exponent
`+, -, *, /, //, %`	Addition, Subtraction, Multiplication, Division, Floor division, Modulus
`< > <= >= == !=`	Comparison operators
`= %= /= //= -= += = *=`	Assignment Operators
`is is not`	Identity operators
`in not in`	Membership operators
`not or and`	Logical operators

Function	Description
any()	Return True if any element of the list is true. If the list is empty, return False.
all()	Returns `True` if all elements of an iterable are true
len()	Return the length (the number of items) in the list.
list()	Convert an iterable (tuple, string, set, dictionary) to a list.
max()	Return the largest item in the list.
min()	Return the smallest item in the list
sorted()	Return a new sorted list (does not sort the list itself).
reversed()	Returns a reverse iterator
sum()	Return the sum of all elements in the list.

Methods	Functions
append()	to add element to the end of the list
extend()	to extend all elements of a list to the another list
insert()	to insert an element at the another index
remove()	to remove an element from the list
pop()	to remove elements return element at the given index
clear()	to remove all elements from the list
index()	to return the index of the first matched element
count()	to count of number of elements passed as an argument
sort()	to sort the elements in ascending order by default
reverse()	to reverse order element in a list
copy()	to return a copy of elements in a list

Table of Contents

Basics¶

`print()` function:¶

comment with `#` symbol:¶

Operators¶

Primitive Data Types¶

Booleans¶

Numbers¶

integer¶

float¶

complex¶

Strings¶

Date and Time¶

Data Structures¶

Composite Data Types¶

Lists¶

Tuples¶

Collection data types¶

Dictionaries¶

Sets¶

Data types Tree¶

Queues(FIFO) and Stacks(LIFO)¶

Type conversion¶

Implicit type conversion¶

Explicit type conversion¶

Table of Contents

Basics¶

print() function:¶

comment with # symbol:¶

Operators¶

Primitive Data Types¶

Booleans¶

Numbers¶

integer¶

float¶

complex¶

Strings¶

Date and Time¶

Data Structures¶

Composite Data Types¶

Lists¶

Tuples¶

Collection data types¶

Dictionaries¶

Sets¶

Data types Tree¶

Queues(FIFO) and Stacks(LIFO)¶

Type conversion¶

Implicit type conversion¶

Explicit type conversion¶

`print()` function:¶

comment with `#` symbol:¶