1.

isinstance(2, int)
type() method gives you the type, used for chekcking
isinstance() returns bool there works for checking and can be used as statement in code
In [1]: l = [1,2,3,4,5]
l[3]

s = l[2]

isinstance(s,int)

Out[1]: True

In [2]: lmn = [1,2,3,1,2,3]

type(lmn)

if isinstance(lmn, list):
s = set(lmn)
print(s)

{1, 2, 3}

2. Range is a class in intself

In [45]: x = range(6)
print(x)
print(list(x))
print(type(x))

range(0, 6)
[0, 1, 2, 3, 4, 5]
<class 'range'>

3. bool()
In [46]: #converts non empty string or non zero numeric value to True bool﴾5﴿, bool﴾' '﴿
#converts empty string or zero numeric value to False bool﴾0﴿, bool﴾''﴿
bool(234)
bool(0)#False
bool('') #False
bool(' ')

Out[46]: True

In [5]: s = input()
if bool(s):
print(s)
else:
print('It is empty')

hello
hello

4. Format Specifier
In [6]: # pi_approx = 22 / 7
# print﴾f'The value of pi is approximately {pi_approx:.2f}'﴿
#print﴾'The value of pi is approximately {:.2f}'.format﴾pi_approx﴿﴿
#print﴾f'The value of pi is approximately %.2f'%﴾pi_approx﴿﴿
#print﴾'{0:5d}'.format﴾1﴿﴿
#print﴾'{:5d}'.format﴾111111﴿﴿
# :.2f, %.2f
pi = 3.146957846393
f'{pi:.2f}'
print('{}'.format(pi))
print('{:.3f}'.format(pi))
print('{0:5d}'.format(1))
print('{0:5d}'.format(123))

3.146957846393
3.147
1
123

5. not > and > or

6. Identity and Membership
In [7]: # is ­ object identity
#is not ­ negated object identity
# in ­ membership
#not in ­ negated membership
#example1:
num = '9874648393'
if num[0] in '6849':
print(bool('yes')) #first digit can only be one of 6849, verify it

print('**********************')

l = [1,2,3,4,5,6,7, 0]
if 9 not in l:
print('not found')
if 0 in l:
print('found')

True
**********************
not found
found

In [8]: #example2:
s = '76544666666'
if 6*'6' in s:#6 cannot be repeated more than 5 times continously
print('invalid')
if '9812' not in s:
print('valid')

invalid
valid

In [9]: #is keyword example

l = [1,2,3]
l_notcopy = l
l_copy1 = list(l)
l_copy2 = list.copy
l_copy3 = l[:]
for i in range(1):
print(l_notcopy is l, l_copy1 is l, l_copy2 is l, l_copy3 is l)

True False False False

In [11]: #On a SIDE NOTE

# copying a tuple
tuple1 = (1, 2, 3)
tuple2 = tuple(tuple1)
tuple3 = tuple1[:]
#tuple4 = tuple1.copy﴾﴿ # does not work
for i in range(1):
print(tuple1 is tuple2, tuple1 is tuple3)
dict1 = {1:1,2:2}
# copying a dict
dict2 = dict(dict1)
dict3 = dict1.copy()

True True

7. Integer representation of ASCII Code ord('^')

In [12]: char = 'abcdefghijklmnopqrstuvwxyz'
for i in char:
print(ord(i))
#ord﴾'^'﴿

97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122

8. sizeof
In [13]: #__sizeof__﴾﴿

In [14]: from random import randint

l = []
for i in range(100):
l.append(randint(1,365))
l.__sizeof__()
tuple(l).__sizeof__()
str(l).__sizeof__()

Out[14]: 524

In [15]: for i in range(1):

print('list size in bytes:',l.__sizeof__())
print('tuple size in bytes:',tuple(l).__sizeof__())
print('string size in bytes:',str(l).__sizeof__())

list size in bytes: 888

tuple size in bytes: 824
string size in bytes: 524

9. Range in for loop

In [16]: #eg1:
for i in range(3):
print(i) #iterates 3 times upto 3­1 index ﴾0,1,2﴿

0
1
2

In [17]: #eg2:
y = 'abc'
for i in range(len(y)):
print(i)

0
1
2

In [18]: #eg3: power od step function combines with f string

for i in range(1,10,3):
print(f'|{i}{i+1}{i+2}', end = '')
print('|')

|123|456|789|

In [19]: # character 'h' 'e' 'l' 'l' 'o'

# left to right ﴾positive indexing﴿ 0 1 2 3 4
# right to left ﴾negative indexing﴿ ­5 ­4 ­3 ­2 ­1
s = 'hello'
for i in range(0, len(s)): #starts from 0 goes to index 1 less than len﴾s﴿
print(s[i])
#print﴾s[­5]﴿
#s[­5:­3:1]
#s[­1:­3:­1]

h
e
l
l
o

10. enumerate(iterable)
string, list, tuple are iterable
In [20]: for i in enumerate('hello'):
print(i)

(0, 'h')
(1, 'e')
(2, 'l')
(3, 'l')
(4, 'o')

In [21]: for index, val in enumerate('hello'):

print(index, val)

0 h
1 e
2 l
3 l
4 o

In [22]: for index, val in enumerate('hello'):

print(index)

0
1
2
3
4

In [23]: t = 1,2,3
for index, val in enumerate(t):
print(index, val)

0 1
1 2
2 3

In [24]: l = [1,2,3]
for index, val in enumerate(l):
print(index, val)

0 1
1 2
2 3

11. math library

In [27]: import math
from math import trunc, exp, fabs, ceil, floor
math.trunc(1.2345)

Out[27]: 1

In [28]: math.exp(1)

Out[28]: 2.718281828459045

In [29]: from math import e, inf, nan, pi

math.pi

Out[29]: 3.141592653589793

In [30]: import math

try:
5/0
except Exception as e:
print(math.nan, 'error')

nan error

11.1 random Library

In [31]: from random import random,randint,choice, choices

In [32]: random()

Out[32]: 0.05486655111991212

In [33]: randint(1,365) #including 1 and 365

Out[33]: 130

In [34]: #choice﴾﴿ accepts any sequence as input

#and returns an element chosen at random from this sequence.
choice(['a','b','c']) #list

Out[34]: 'b'

In [35]: choice(('a','b','c')) #tuple

Out[35]: 'a'

In [ ]:

11.2 calendar Library

In [36]: from calendar import prmonth, weekday

In [37]: prmonth(2021,7)

July 2021
Mo Tu We Th Fr Sa Su
1 2 3 4
5 6 7 8 9 10 11
12 13 14 15 16 17 18
19 20 21 22 23 24 25
26 27 28 29 30 31

In [38]: weekday(2021,7,4)

Out[38]: 6

In [39]: from time import ctime

print(ctime())

Thu Aug 5 00:25:17 2021

12. Built‑in functions

In [40]: #min﴾﴿,max﴾﴿,abs﴾﴿,round﴾﴿,help﴾﴿, id﴾﴿, ord﴾﴿
lst = [5,2,3]
print('lst: ', lst)
for i in range(1):
print('min value: ',min(lst))
print('max value: ',max(lst))
print('sum: ',sum(lst))
print('after sorting: ',sorted(lst))
print('absolute value of ­3.567: ',abs(­3.567))
print('3.142858 rounded off to 3 digs: ',round(3.142858,3))
print('memory loc is: ',id(lst))
#help﴾range﴿
id('a') # This value is the memory address of the object
#and will be different every time you run the program
chr(97) #The valid range of the integer is from 0 through 1,114,111
ord('a') #opposite of chr

lst: [5, 2, 3]
min value: 2
max value: 5
sum: 10
after sorting: [2, 3, 5]
absolute value of ­3.567: 3.567
3.142858 rounded off to 3 digs: 3.143
memory loc is: 140545729149056
Out[40]: 97

In [41]: #sorted also works for string type ﴾unlike l.sort﴾﴿﴿

#but after sorting it returns as a list as shown below
s = 'zxt'
s_new = sorted(s)
print(s_new)
#however if you want to convert back into string ﴾list to string WOW how????﴿
print(*s_new, sep=',')
print(*s_new, sep='')
print(*s_new, sep=' ')

['t', 'x', 'z']

t,x,z
txz
t x z

13. Parameter and Arguments

variables used in function definition are called parameters
values passed to a function call are called arguments
Parameters that are assigned a value in the function definition are called default parameters.
Default parameters always come at the end of the parameter list in a function definition.
The argument corresponding to a default parameter is optional in a function call.
14. Call By Value (Inside Fn Vs Outside Fn)
Passing arguments like whole numbers, strings or tuples* to a function, you can not change the value of these as they are constant
literals
tuple should be formed using int , float or strings or using immutable objects (HASHABLE)
values (elements) that are changed INSIDE the function, are NOT changed OUTSIDE the function.
In [42]: def double(x):
x=x*2
return x

a = 4
print(double(a))
print(a)

8
4

In [43]: def double(x):

x=x*2
return x

a = 's'
print(double('s'))
print(a)

ss
s

15. Call By Reference (Inside Fn Vs Outside Fn)

passing mutable objects like list can be considered as call by reference because when their values (elements) are changed INSIDE
the function, then it will ALSO be reflected OUTSIDE the function.
In [44]: def double(l):
return l.append(100)

l = [1,23,45,7]
print(f'before: {l}')
double(l)
print(f'after: {l}')
print(l)

before: [1, 23, 45, 7]

after: [1, 23, 45, 7, 100]
[1, 23, 45, 7, 100]

In [ ]:

16. Create Global Variable inside a function

When we create a variable inside a function, it is local by default.
When we define a variable outside of a function, it is global by default. You don't have to use global keyword. If we do not declare a
variable as a global inside function, We can only access the global variable but cannot modify it.
We use global keyword to create a global variable or modify a global variable inside a function.
Local variable takes over global inside the function if the global variable and local variable have the same name
Use of global keyword outside a function has no effect.
In [45]: def foo():
global x
x = 'global'
print("x inside:", x)
foo()
print("x outside:", x)

x inside: global
x outside: global

In [ ]: # #Example1:
# def foo﴾﴿:
# # print﴾x﴿ # UnboundLocalError: local variable 'x' referenced before assignment
# x = "local"
# print﴾f'x inside foo = {x}'﴿
# x = "global"
# foo﴾﴿
# print﴾f'x outside foo = {x}'﴿

# #Example 2:
# def foo﴾﴿:
# global x
# print﴾f'x inside foo = {x}'﴿
# x=x+1
# print﴾f'x inside foo = {x}'﴿
# x = 10
# print﴾f'x outside foo = {x}'﴿
# foo﴾﴿
# print﴾f'x outside foo = {x}'﴿

# #Example 3:
# def foo﴾﴿:
# print﴾f'x inside foo = {y}'﴿ # SyntaxError: name 'x' is used prior to global declaration
# global y
# y = "global again"
# y = "global"
# foo﴾﴿
# print﴾f'x outside foo = {y}'﴿

17. iter()
In [46]: patients = ['p01','p02','p03','p04']
doctor = iter(patients)
for i in range(5):
print(next(doctor))

p01
p02
p03
p04
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
StopIteration Traceback (most recent call last)
<ipython­input­46­57e52426bdcb> in <module>
2 doctor = iter(patients)
3 for i in range(5):
­­­­> 4 print(next(doctor))

StopIteration:

18. Generator
In [42]: def foo(limit):
x = 0
while(x<limit):
yield x* x
yield x* x * x
x += 1
try:
a = foo(4)
print(next(a), next(a))
print(next(a), next(a))
print(next(a), next(a))
print(next(a), next(a))
print(next(a), next(a))
except Exception as e:
print(e)

0 0
1 1
4 8
9 27

In [38]: def gen(n):

for i in range(n):
yield i
A = gen(5)

print(next(A))
print(next(A))

0
1

In [39]: def gen(n):

for i in range(n):
yield i
A = gen(5)

for i in A:
print(i)

0
1
2
3
4

In [41]: def gen(n):

for i in range(n):
yield i
for i in gen(5):
print(i)
print(type(A))

0
1
2
3
4
<class 'generator'>

In [ ]:

19. List from Dictionary

list_from_dict = list({'one':1,'two':2,'three':3,}.keys())
list_from_dict = list({'one':1,'two':2,'three':3,}.values())
list_from_dict = list({'one':1,'two':2,'three':3,}.items())
In [48]: list_from_dict = list({'one':1,'two':2,'three':3,}.keys())
list_from_dict

Out[48]: ['one', 'two', 'three']

In [49]: list_from_dict = list({'one':1,'two':2,'three':3,}.values())

list_from_dict

Out[49]: [1, 2, 3]

In [50]: list_from_dict = list({'one':1,'two':2,'three':3,}.items())

list_from_dict

Out[50]: [('one', 1), ('two', 2), ('three', 3)]

20. First and Last Element

In [51]: L = [10,20,30,40,50]
print(L[0], L[len(L)­1]) #last element = index value @ len﴾list﴿ ­ 1
print(L[1:­1]) #exclude first and last element
S = '[Mumbai]'
# remove the brackets i.e remove first and last char values from S
print(S[1:­1])

10 50
[20, 30, 40]
Mumbai

21. Multiple list update

In [52]: L = [10,20,30,40,50]
#remove 30 update first 2 elements of the list with 80 and 90
L[1:3] = [80, 90] #multiple update at once
print(L)
L[0:3] = [80, 90] #updates first 3 index 0,1,2 with 2 values 80, 90
print(L) #value 30 gor deleted

[10, 80, 90, 40, 50]

[80, 90, 40, 50]

22.Tuple
possible ‑Immutable, Ordered, Indexed, Iteration possible, Slicing
"T[im] [Ordered] a [Tuple] from an {Indian} {IT} company and {SLICED} into pieces."
"T[im] [immutable] [Ordered] a [Tuple] from an {Indian}(indexing) {IT}(Iterable) company and {SLICED}(slicing) into pieces."
tuple: Immutable, Ordered, Indexed, Iteration possible, Slicing possible
SORTING NOTPOSSIBLE
In [53]: t = 1,2,3
print(t)

#IMMUTABLE
#t[0] = 5 #TypeError: 'tuple' object does not support item assignment

#INDEXABLE
print(t[1])

#ITERABLE
for i in t:
print(i)

#SLICABLE
print(t[::­1])

(1, 2, 3)
2
1
2
3
(3, 2, 1)

In [54]: #'UNHASHABLE elements﴾mutable elements﴿ in a tuple' example

t = ([1,23,4],)
print(t)
print(type(t))
print(t[0][1])
t[0][1] = 77 #UNHASHABLE ==> Values can be CHANGED/MANIPULATED
print(t)

([1, 23, 4],)

<class 'tuple'>
23
([1, 77, 4],)

In [55]: #'Hashable elements in a tuple' example ==> ITEM ASSIGNEMNT NOT POSSIBLE
t = (1,2,3)
print(t[0])
t[0] = 77 #'tuple' object does not support item assignment

1
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
TypeError Traceback (most recent call last)
<ipython­input­55­eda4d066cf5f> in <module>
2 t = (1,2,3)
3 print(t[0])
­­­­> 4 t[0] = 77 #'tuple' object does not support item assignment

TypeError: 'tuple' object does not support item assignment

In [56]: #TUPLE METHODS

my_tuple = ('a', 'p', 'p', 'l', 'e',)
print(my_tuple.count('p'))
print(my_tuple.index('l'))

2
3

In [57]: #Since indexing is possible ==> slicing is also possible

t = (1,2,3,4,5)
print(t[0:3])

(1, 2, 3)

23. Set ‑ hashable, unordered, mutable, add, delete, iterable

INDEXING NOT POSSIBLE (since they are unordered, indexing doesnot make any sense)
SLICING NOT POSSIBLE
SORTING NOT POSSIBLE
Remeber 'HIM' ‑HashableImmutable
Close Your Eyes, think of the you favorite 'AD & HUM IT' and repeat again, write a SET of all such ads
'AD HUM IT' ‑ Add Delete Hashable Unordered Mutable Iterable
In [58]: #Only Hashable﴾immutable﴿ elements are allowed
s = {1,2,3}
print(s)
#print﴾s[0]﴿ #indexing, slicing not possible

{1, 2, 3}

In [59]: #unhashable type cannot be elements

s1={[1,2,3],[4,5,6]}
print(s1) #TypeError: unhashable type: 'list'

­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
TypeError Traceback (most recent call last)
<ipython­input­59­08dc1ffe917f> in <module>
1 #unhashable type cannot be elements
­­­­> 2 s1={[1,2,3],[4,5,6]}
3 print(s1) #TypeError: unhashable type: 'list'

TypeError: unhashable type: 'list'

In [12]: #unordered #mutable #add #delete elements

#if you can add/discard/update elements ==> mutable ﴾manipulation is possible﴿
s2 = {'a','b', 123}
print(s2)
s2.add(777)
print(s2)
s2.discard(777)
print(s2)
s2.update(['hello','mars'])
print(s2)

{'b', 123, 'a'}

{'b', 777, 123, 'a'}
{'b', 123, 'a'}
{'hello', 'b', 'a', 123, 'mars'}

In [ ]:

24. Dictionary ‑ #DOM

Ordered
Mutable
Hashable(immutable) Keys
Sorting Possible
In [61]: my_dict = dict([(1,'apple'), (2,'ball')]) # {1: 'apple', 2: 'ball'}
print(my_dict)

dict1 = {'a':1, 'b':2, 'c':3}

print(('a',1) in dict1.items())

# copying a dict
dict2 = dict(dict1)
dict3 = dict1.copy()

{1: 'apple', 2: 'ball'}

True

In [13]: #SORTING IS POSSIBLE

d = {1:10, 3:30, 5:50, 2:20}
print(sorted(d.keys()))
print(sorted(d.values()))
print(sorted(d.items())) #proof

[1, 2, 3, 5]
[10, 20, 30, 50]
[(1, 10), (2, 20), (3, 30), (5, 50)]

In [8]: #duplicate keys

d1 = {1:23, 2:24, 1:456}
d1

Out[8]: {1: 456, 2: 24}

In [6]: #All 5 types of possible keys

d = {11:123, 1.1:234, 'a':234, (1,2):567, True: 6789}
d

Out[6]: {11: 123, 1.1: 234, 'a': 234, (1, 2): 567, True: 6789}

In [7]: #1 and True as keys are same?

d = {1:123, 1.1:234, 'a':234, (1,2):567, True: 6789}
d

Out[7]: {1: 6789, 1.1: 234, 'a': 234, (1, 2): 567}

24.1 Comparision on a few methods

In [3]: a = [1,2,3,4,5]
b = (1,2,3,4,5)
c = {1,2,3,4,5}
d = {1:10, 2:20, 3:30, 4:40, 5:50}
print(len(a), min(a), max(a), sum(a))
print(len(b), min(b), max(b), sum(b))
print(len(c), min(c), max(c), sum(c))
print(len(d), min(d), max(d), sum(d)) #considers only keys

5 1 5 15
5 1 5 15
5 1 5 15
5 1 5 15

In [ ]:

25. Inline Statements

inline if‑else
inline while loop
inline for loop ( A { F In } ) alias LIST COMPREHENSION
In [62]: #inline if ­ else
a = 34
b = 45
small = a if a<b else b
print(small)

#inline while loop ﴾recommended only for small statements﴿

x = 3
while x>0: print(x); x­=1

34
3
2
1

In [23]: #inline for loop ­ LIST COMPREHENSION

#case1: ﴾ A { F In } ﴿ a﴿ Append For Loop If/Nested If
#case2: ﴾ A { IE F} ﴿ b﴿ Append If Else For Loop

#Model#1: AF ﴾append, for loop﴿

L = [1,2,3,4,5]

print([i for i in range(10)])

print([(i, i**2)for i in L])

print([(i,j)for i,j in enumerate(L)])

print([(i+1,j*j)for i,j in enumerate(L)])

d= {1:10, 4:20, 3:19, 6:29 }

print([(i, j[0], j[1]) for i, j in enumerate(d.items())])

#Model#2: AFI ﴾append, for in list, if statement﴿

fruits = ["apple", "banana", "cherry", "kiwi", "mango"]
newlist = [x for x in fruits if "a" in x]
print(newlist)

lst = [x for x in range(10) if (x<5) ]

print(lst)

#Model3: AIF ﴾append if­else, for loop﴿

newlist3 = [x if x != "banana" else "orange" for x in fruits]
print(newlist3)

#misq:
fruits = ["apple", "banana", "cherry", "kiwi", "mango"]
newlist2 = ['hello' for x in fruits]
print(newlist2)

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
[(1, 1), (2, 4), (3, 9), (4, 16), (5, 25)]
[(0, 1), (1, 2), (2, 3), (3, 4), (4, 5)]
[(1, 1), (2, 4), (3, 9), (4, 16), (5, 25)]
[(0, 1, 10), (1, 4, 20), (2, 3, 19), (3, 6, 29)]
['apple', 'banana', 'mango']
[0, 1, 2, 3, 4]
['apple', 'orange', 'cherry', 'kiwi', 'mango']
['hello', 'hello', 'hello', 'hello', 'hello']

26. Nested For Loop

In [66]: word = ''.join(sorted(input()))
for a in word:
for b in word:
for c in word:
print(a, b, c, sep = '')

xhy
hhh
hhx
hhy
hxh
hxx
hxy
hyh
hyx
hyy
xhh
xhx
xhy
xxh
xxx
xxy
xyh
xyx
xyy
yhh
yhx
yhy
yxh
yxx
yxy
yyh
yyx
yyy

In [43]: #row and column swap logic for a matrix

In [67]: # 1,2,3
# 4,5,6
# 7,8,9
#row
# 7,8,9
# 4,5,6
# 1,2,3
n = 3
for i in range(n):
for j in range(n):
print(i,j, '­' ,n­i­1,j)
#out[i][j] = mat[n ­ i ­ 1][j]

0 0 ­ 2 0
0 1 ­ 2 1
0 2 ­ 2 2
1 0 ­ 1 0
1 1 ­ 1 1
1 2 ­ 1 2
2 0 ­ 0 0
2 1 ­ 0 1
2 2 ­ 0 2

In [68]: # 1,2,3
# 4,5,6
# 7,8,9
# #column
# 3,2,1
# 6,5,4
# 9,8,7
n = 3
for i in range(n):
for j in range(n):
print(i,j, '­' ,n­j­1,i)
#out[i][j] = mat[n ­ i ­ 1][j]

0 0 ­ 2 0
0 1 ­ 1 0
0 2 ­ 0 0
1 0 ­ 2 1
1 1 ­ 1 1
1 2 ­ 0 1
2 0 ­ 2 2
2 1 ­ 1 2
2 2 ­ 0 2

27. lambda functions

writing functions without function name
also known as anonymous functions
using lambda function you are creating varaibles which are of type function
In [69]: x = 5
y = 10

add = lambda x,y: x+y

sub = lambda x,y: x­y
mul = lambda x,y: x*y
div = lambda x,y: x/y

print(add, sub, mul, div)

print(type(add))
result = add(10,20)
print(result)
print(sub(10,20))

<function <lambda> at 0x7fd35a470af0> <function <lambda> at 0x7fd35a545dc0> <function <lambda> at 0x7fd35a545f7

0> <function <lambda> at 0x7fd35a545e50>
<class 'function'>
30
­10

28. zip function

In [70]: msg = ['hello', 'mars', 'we', 'are', 'coming']
size = [5, 4, 2, 3, 6]

print(type(zip(msg, size)))

<class 'zip'>

In [72]: print((zip(msg, size)))

<zip object at 0x7fd35a55c280>

In [73]: print(list(zip(msg, size))) #list of tuples from corresponding elements from 2 lists

[('hello', 5), ('mars', 4), ('we', 2), ('are', 3), ('coming', 6)]

In [74]: print(dict(zip(msg, size))) #2 lists ­­­>into a dictionary

{'hello': 5, 'mars': 4, 'we': 2, 'are': 3, 'coming': 6}

In [75]: print(tuple(zip(msg, size)))

(('hello', 5), ('mars', 4), ('we', 2), ('are', 3), ('coming', 6))

In [76]: print(set(zip(msg, size))) #the out proves the set is in unordered entity

{('we', 2), ('are', 3), ('mars', 4), ('coming', 6), ('hello', 5)}

29. map()
map function takes 2 different types of parameters a) function name b) parameters of that function
b)parameters of that function in the below example is a list ‑‑> the value gets reflected as it interates over each element
In [83]: a = [10,20,30,40,50]
b = [1,2,3,4,5]

def sub(x,y):
return x ­ y
c = map(sub, a,b) #example ­ 1
print(c)
print(list(c))

def incr(x):
return x+1
d = map(incr, a) #example ­ 2
print(list(d))

<map object at 0x7fd35a4b7dc0>

[9, 18, 27, 36, 45]
[11, 21, 31, 41, 51]

In [26]: #example of map menthod in combination with lambda function

L = [1,2,3,4,5,6]
print(list(map(lambda i:i*i, L)))

[1, 4, 9, 16, 25, 36]

30. filter()
In [33]: L = [1,2,3,4,5,6]
print(list(filter(lambda i: i>3, L )))

[4, 5, 6]

In [ ]:

Some Cool Tricks: (ROUTINES)

1. print(*L, sep=", ")
The only downside of this is ‑ you can only print it cannot be saved to a variable
to save it to a variable use the join method as below:
In [90]: L=[1,2,3,4,5,6,5,4,3,2,1,0,­1,2.1,3.2,4.0001,­5.3]
M=["Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"]

print(*L, sep=", ")

print(*M, sep=", ")

1, 2, 3, 4, 5, 6, 5, 4, 3, 2, 1, 0, ­1, 2.1, 3.2, 4.0001, ­5.3

Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec

In [91]: ##Example1:
words = ['this', 'is', 'false'] # a list of words
s = ''
for word in words:
s += word + ' ' # appends words to string variable s
print(s) # a string with multiple words

#All the above in 1 line of code as below:

print(*words, sep=' ')

this is false
this is false

In [92]: ##Example2:
words = ['this', 'sentence', 'is', 'false']
s = ' '.join(words)
print(s)

#All the above in 1 line of code as below:

print(*words, sep=' ')

this sentence is false

this sentence is false

2. Create Matrix from user input

In [93]: dim = 3 #can also be made user input
mat = []
for i in range(dim):
mat.append([]) #initializing an empty matrix
for num in input().split(): #space seperated input
mat[­1].append(int(num))
print(mat)

1 2 3
4 5 6
7 8 9
[[1, 2, 3], [4, 5, 6], [7, 8, 9]]

3. Unpack the user input to variables

string
list
tuple
range
In [94]: eq1 = [int(word)for word in input().split()]
x,y,z = eq1
print(eq1)
print(x)
print(y)
print(z)

12 34 56
[12, 34, 56]
12
34
56

In [95]: # more unpacking of sequence type collections

l1, l2, l3, l4 = 'good' # string
num1, num2, num3 = [1, 2, 3] # list
b1, b2 = (True, False) # tuple
x, y, z = range(3) # range
print(l1,l2,l3,l4)
print(num1,num2,num3)
print(b1,b2)
print(x,y,z)

g o o d
1 2 3
True False
0 1 2

4. List/Tuple with str elements to String

In [96]: l = ['1','2','76']
x = ''.join(l)
print(x)
print(*l,sep='')

1276
1276

In [97]: t = ('1','2','76')
x = ''.join(t)
print(x)

1276

In [98]: d = {'1': 123,'2':456,'76':890}

x = ''.join(d)
print(x)

1276

In [99]: d = {'1': 123,'2':456,'76':890}

x = ''.join(d.keys()) #same as above code d.items﴾﴿, d.values﴾﴿ throws error
print(x)

1276

5. Sort a String
In [100… l = ['c','d','a']
x = ''.join(sorted(l))
print(x)

acd

In [101… x = ''.join(sorted(input()))
print(x)

hello
ehllo

6. Read Each Line from a File

row = [int(num) for num in line.strip().split(',')]
In [102… f = open('test.txt')
lines = f.readlines()
print(lines)

['1,2,3,4,45\n', '34,45,6,7,7,8,9,9,0']

In [103… f = open('test.txt')
lines = f.readlines()
lst = []
for line in lines:
row = [int(num) for num in line.strip().split(',')]
lst.append(row)
print(lst)

print(*lst[0], sep=',')

[[1, 2, 3, 4, 45], [34, 45, 6, 7, 7, 8, 9, 9, 0]]

1,2,3,4,45

In [ ]:

MiniPacks
1. OOPS
In [106… #Example of Hierarichal Inheritance
class Person: #Parent Class
def __init__(self, a, b):
self.name = a
self.age = b
def display(self):
print(self.name, self.age)
class Student(Person): #Child 1 Class
def __init__(self,a,b,c):
super().__init__(a,b)
self.marks = c
def display(self):
super().display()
print(self.marks)
class Employee(Person): #Child 2 Class
def __init__(self, a,b,c):
super().__init__(a,b)
self.salary = c
def display(self):
super().display()
print(self.salary)

s1 = Student('venu', 35, 160)

s1.display()
e1 = Employee('priyam', 56, 50_000)
e1.display()

venu 35
160
priyam 56
50000

In [105… class Foo:

def a_method(self):
print('calling from Foo')
class Bar(Foo):
def a_method(self):
print('calling from Bar')
class FooBar(Foo):
def a_method(self):
super().a_method()
print('calling from FooBar as well')

obj_1 = Foo()
obj_1.a_method()
obj_2 = Bar()
obj_2.a_method()
obj_3 = FooBar()
obj_3.a_method()

calling from Foo

calling from Bar
calling from Foo
calling from FooBar as well

1.1 On the Fly

Object attributes can be created ON THE FLY
In [107… class Foo:
def __init__(self):
print('Foo object created')
obj = Foo()
obj.x = 10
print(obj.x)

Foo object created

10

In [108… class Foo:

x=0
obj = Foo()
print(obj.x)
obj.x = obj.x + 10
print(obj.x, Foo.x)

0
10 0

Some important lessons from above 2 code blocks(1.1):

A class attribute's state can never be explicitly altered by an object. However, it can be changed by using methods.
A class attribute can be referenced by an object, provided there is no object attribute with the same name.
If the same variable name is shared by a class attribute and an object attribute, while trying to access attributes using an object,
Python gives precedence to the object attribute.
In [ ]:

2. Star Variable
In [109… def foo(a, b):
print(a, b)

def bar(*a):
print(a)

def foobar(a, b, *c):

print(a, b, c)

lst = [3, 4]
foo(1, 2)
foo(*lst)

bar(lst)
bar(*lst)
bar()

bar(1, 2)
bar(1, 2, 3, 4)

bar(1, 2, *lst)
bar(1, 2, lst)

foobar(1, 2, 3, 4, 5)
foobar(1, 2)

foobar(*lst)
foobar(1, 2, *lst)
foobar(1, 2, 3, *l)

1 2
3 4
([3, 4],)
(3, 4)
()
(1, 2)
(1, 2, 3, 4)
(1, 2, 3, 4)
(1, 2, [3, 4])
1 2 (3, 4, 5)
1 2 ()
3 4 ()
1 2 (3, 4)
1 2 (3, 'c', 'd', 'a')

In [ ]: ## 3. Writing to a File

In [ ]: f = open('file.txt', 'w')
while True:
line = input()
if line == '':
break
f.write(line+'\n')
f.close()

In [ ]:

Selected Problems from the Course

Recommended
code method: Read the Question and without looking solution just keep writing the
The main goal(s) of these selected problems from the course are the following:
1. Fixing time and practising in one go will act as warm up
2. Warm up before an exam
3. Warm up of Python after short or long gap of non‑use of Python
4. To increase confidence/morale
5. To develop programming intuition
Week 2
'''Problem 2: Find whether the given number ends with 0 or 5 or any other number'''
In [112… # num = int﴾input﴾'Enter a number: '﴿﴿
# if﴾num % 5 == 0﴿:
# if﴾num % 10 == 0﴿:
# print﴾'0'﴿
# else:
# print﴾'5'﴿
# else:
# print﴾'Other'﴿

#alternative method
num = input()
if num[len(num)­1] in '05':
print('end with either 0 or 5')
print(num[len(num)­1])
else:
print('any other number')

345678908
any other number

Week 3
'''Problem 1: Find the factorial of the given number'''
In [113… #n = int﴾input﴾﴿﴿
n = 5
# 5 * 4 * 3 * 2 * 1
# 1 * 2 * 3 * 4 * 5
mul = 1
for i in range(1,6): #using for loop
mul *= i
print(mul)

120

In [117… n = 5
mul = 1
while(n>0): #using while loop
mul = mul * n
n = n­1
print(mul)

120

'''Problem 2: Find the number of digits in the given number'''

In [118… #method1
num = abs(int(input('Enter a number: ')))
digits = 1
while(num > 10):
num = num // 10
digits = digits + 1
print(digits)

Enter a number: 12345

5

In [121… #method2:
num = abs(int(input('Enter a number: ')))
num_str = str(num)
print(len(num_str))

Enter a number: 12345

5

'''Problem 3: Reverse the digits in the given number'''

In [123… #method 1
num = int(input('Enter a number: '))
absNum = abs(num)
rev = absNum % 10
absNum = absNum // 10
while(absNum > 0):
r = absNum % 10
absNum = absNum // 10
rev = rev * 10 + r
if(num > 0):
print(rev)
else:
print(rev ­ 2 * rev)

Enter a number: 12345

54321

In [127… #method ­2
num = str(abs(int(input())))
print(int(num[::­1]))

12345
54321

'''Problem 4: Find whether the entered number is palindrome or not'''

In [128… #method ­ 1
num = int(input('Enter a number: '))
absNum = abs(num)
rev = absNum % 10
absNum = absNum // 10
while(absNum > 0):
r = absNum % 10
absNum = absNum // 10
rev = rev * 10 + r
if(num < 0):
rev = rev ­ 2 * rev
if(rev == num):
print('Palindrome')
else:
print('Not a palindrome')

Enter a number: 1234321

Palindrome

In [138… #method ­2
n = input()
if n.isdigit():
if n[::] == n[::­1]:
print('palindrome')
else:
print('not palindrome')

1234321
palindrome

'''Problem 1: Find all prime numbers less than the entered number'''
In [139… #method ­ 1
num = int(input('Enter a number: '))
if(num > 2):
print(2, end = ' ')
for i in range(3, num):
flag = False
for j in range(2, i):
if(i % j == 0):
flag = False
break
else:
flag = True
if(flag):
print(i, end = ' ')

Enter a number: 67
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61

In [151… #method ­ 2
def isPrime(n):
for i in range(2, n):
if n%i == 0:
return False
return True

def primeNums(n):
result = []
for i in range(2,n):
if isPrime(i):
result.append(i)
return result

n = int(input('Enter a number: '))

print(*primeNums(n))

Enter a number: 67
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61

'''Problem 4: Find the length of longest word from the set of words entered by the user'''
In [153… #method ­ 1
word = input('Enter a word: ')
maxLen = 0
while(word != '­1'):
count = 0
for letter in word:
count = count + 1
if(count > maxLen):
maxLen = count
word = input('Enter a word: ')
print('The length of longest word is %s' %maxLen)

Enter a word: hello

Enter a word: mars
Enter a word: we
Enter a word: are
Enter a word: coming
Enter a word: ­1
The length of longest word is 6

In [159… # my code
print('input a word and press enter to input second word')
print('input ­1 if you have finished entering words')
def wordLen(word):
return len(word)

word = input()
len_word = []
n = []
while(word != str(­1)):
len_word.append(word)
n.append(wordLen(word))
word = input()

print(max(n))

input a word and press enter to input second word

input ­1 if you have finished entering words
hello
mars
we
are
coming
­1
6

Week 4
In [172… #Birthday Paradox
from random import randint
n = 30
lst = []
for i in range(n):
lst.append(randint(1,365))
lst.sort()
print(lst)
i = 0
flag = False
while(i<(len(lst)­1)):
if lst[i] == lst[i+1]:
print('Repeats', lst[i])
flag = True
i = i+1
if not flag:
print('Doesnot Repeat')

[10, 34, 92, 100, 117, 135, 135, 152, 159, 175, 176, 201, 202, 227, 238, 251, 259, 261, 262, 293, 310, 315, 32
2, 323, 328, 345, 347, 356, 361, 361]
Repeats 135
Repeats 361

In [194… #obvious sort

from random import randint
lst = []
for i in range(25):
lst.append(randint(1,100))
#print﴾lst﴿
#Let us assume the FIRST ELEMENT is of least Value
#Loop over rest of the elements ­ compare with each element
#if any element is least, asign it as min value and append it to a new list
#after appending remove that element
#in the end your new least is an obvious sorted list
x = []
while len(lst)>0:
min = lst[0]
for i in range (len(lst)):
if lst[i] < min:
min = lst[i]

x.append(min)
lst.remove(min)
print(x)
print(lst)

[2, 6, 8, 28, 29, 34, 36, 36, 37, 42, 45, 57, 61, 64, 69, 78, 78, 79, 80, 81, 86, 86, 90, 91, 91]
[]

Week 5
'''Problem 3: Write
form a triangle a Python code using functions which checks whether the input coordinates
or not'''
In [162… '''Approach 1: Using distance between points'''
def distance(xi, yi, xj, yj):
return((((xj ­ xi) ** 2) + ((yj ­ yi) ** 2)) ** 0.5)

def isTriangle(max, a, b):

if((a + b) > max):
print('\nTriangle')
else:
print('\nNot a triangle')

x1 = float(input('Enter x coorinate of 1st point: '))

y1 = float(input('Enter y coorinate of 1st point: '))
x2 = float(input('\nEnter x coorinate of 2nd point: '))
y2 = float(input('Enter y coorinate of 2nd point: '))
x3 = float(input('\nEnter x coorinate of 3rd point: '))
y3 = float(input('Enter y coorinate of 3rd point: '))
d1 = distance(x1, y1, x2, y2)
print(f'\nDistance between points ({x1}, {y1}) and ({x2}, {y2}) = {d1}')
d2 = distance(x2, y2, x3, y3)
print(f'\nDistance between points ({x2}, {y2}) and ({x3}, {y3}) = {d2}')
d3 = distance(x3, y3, x1, y1)
print(f'\nDistance between points ({x3}, {y3}) and ({x1}, {y1}) = {d3}')

if(d1 > d2):

if(d1 > d3):
isTriangle(d1, d2, d3)
else:
isTriangle(d3, d1, d2)
elif(d2 > d3):
isTriangle(d2, d1, d3)
else:
isTriangle(d3, d1, d2)
Enter x coorinate of 1st point: 1
Enter y coorinate of 1st point: 2

Enter x coorinate of 2nd point: 3

Enter y coorinate of 2nd point: 4

Enter x coorinate of 3rd point: 5

Enter y coorinate of 3rd point: 6

Distance between points (1.0, 2.0) and (3.0, 4.0) = 2.8284271247461903

Distance between points (3.0, 4.0) and (5.0, 6.0) = 2.8284271247461903

Distance between points (5.0, 6.0) and (1.0, 2.0) = 5.656854249492381

Not a triangle

In [163… '''Approach 2: Using slope of lines connecting two points'''

import math

def slope(xi, yi, xj, yj):

if(xi == xj):
return(math.inf)
else:
return((yj ­ yi) / (xj ­ xi))

x1 = float(input('Enter x coorinate of 1st point: '))

y1 = float(input('Enter y coorinate of 1st point: '))
x2 = float(input('\nEnter x coorinate of 2nd point: '))
y2 = float(input('Enter y coorinate of 2nd point: '))
x3 = float(input('\nEnter x coorinate of 3rd point: '))
y3 = float(input('Enter y coorinate of 3rd point: '))
s1 = slope(x1, y1, x2, y2)
print(f'\nSlope of the line connecting points ({x1}, {y1}) and ({x2}, {y2}) = {s1}')
s2 = slope(x2, y2, x3, y3)
print(f'\nSlope of the line connecting points ({x2}, {y2}) and ({x3}, {y3}) = {s2}')
if(s1 != s2):
print('\nTriangle')
else:
print('\nNot a triangle')

Enter x coorinate of 1st point: 1

Enter y coorinate of 1st point: 2

Enter x coorinate of 2nd point: 3

Enter y coorinate of 2nd point: 4

Enter x coorinate of 3rd point: 5

Enter y coorinate of 3rd point: 6

Slope of the line connecting points (1.0, 2.0) and (3.0, 4.0) = 1.0

Slope of the line connecting points (3.0, 4.0) and (5.0, 6.0) = 1.0

Not a triangle

In [ ]:

In [ ]: