Module 4.ipynb

Kernel: Python 3

Datastructures

• mutable (elements can change over time)

• immutable (elements cannot change)

Category:

• FIFO (First in First out)

• LIFO (Last in First out)

Type:

• list is mutable

• tuple is immutable

• dictionary is mutable

• set is mutable

a = list((1,2,3,4,5))
dir(a)

['__add__',
 '__class__',
 '__contains__',
 '__delattr__',
 '__delitem__',
 '__dir__',
 '__doc__',
 '__eq__',
 '__format__',
 '__ge__',
 '__getattribute__',
 '__getitem__',
 '__gt__',
 '__hash__',
 '__iadd__',
 '__imul__',
 '__init__',
 '__init_subclass__',
 '__iter__',
 '__le__',
 '__len__',
 '__lt__',
 '__mul__',
 '__ne__',
 '__new__',
 '__reduce__',
 '__reduce_ex__',
 '__repr__',
 '__reversed__',
 '__rmul__',
 '__setattr__',
 '__setitem__',
 '__sizeof__',
 '__str__',
 '__subclasshook__',
 'append',
 'clear',
 'copy',
 'count',
 'extend',
 'index',
 'insert',
 'pop',
 'remove',
 'reverse',
 'sort']

Appending

a.append(6)
a

[2, 3, 4, 5, 6, 6]

Tuples

b = tuple((1,2,3,4,5))
print(b)

(1, 2, 3, 4, 5)

b.count(8)

0

b.index(3)

2

c = {'a':1,'b':2,'c':3}
print (c)

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

c.get('b')

2

c.values()

dict_values([1, 2, 3])

c.keys()

dict_keys(['a', 'b', 'c'])

For Loop

for key in c:
    print(key, c[key])

a 1
b 2
c 3

d = {'a':[1,2,3],'b':[4,5,6],'c':[7,8,9]}
print (d)

{'a': [1, 2, 3], 'b': [4, 5, 6], 'c': [7, 8, 9]}

e = [{'a':1},{'b':2},{'c':3}]
print (e)

[{'a': 1}, {'b': 2}, {'c': 3}]

f = set((1,1,2,2,3,4,4,5,5))
print (f)

{1, 2, 3, 4, 5}

f.add(6)
print(f)

{1, 2, 3, 4, 5, 6}

popped = f.pop()
popped, f

(5, {6})

String functions

-upper()
-lower()
-capitalize()
-split()
-join()
-len()

Character functions

-chr()
-ord()

Upper case conversion

a_string = "pcEp exAm is Cool tO haVe"
a_string.upper()

'PCEP EXAM IS COOL TO HAVE'

a_string

'pcEp exAm is Cool tO haVe'

Lower case conversion

a_string.lower()

'pcep exam is cool to have'

Capitalize first letter conversion

a_string.capitalize()

'Pcep exam is cool to have'

Splitting with a 'character/symbol'

a_string.split(' ')

['pcEp', 'exAm', 'is', 'Cool', 'tO', 'haVe']

a_string.split('p')

['', 'cE', ' exAm is Cool tO haVe']

b_string = "This is another string"

'-'.join([a_string, b_string])

'pcEp exAm is Cool tO haVe-This is another string'

len(a_string)

25

u = 'a'

ord(u)

97

ord('a') + 2

99

i = 112
chr(i)

'p'

chr(ord('p') + 4)

't'

Function and Generators

• Function -> serious memory impact

• Generators -> they minimize memory impact

Results:

• return -> give back the processes results

• yield -> give back one value at a time

• Par and arg:

• arg -> position and order matters

• par -> like keyword arguments

def generate(number):
    a = list()
    for i in range(number):
        a.append(i)
        
    return a

print(generate(59))

[0, 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, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58]

def generate(number):
    a = list()
    for i in range(number):
        yield i
        
print(generate(10000000))

<generator object generate at 0x7ff97003fa50>

print(None)

None

def return_none(whatever):
    print(whatever)
    
a = return_none("This is whatever")
a is None

This is whatever

True

def sum(a, b):
    return a + b

sum(1,5)

6

def general(*args, **kwargs):
    pass

general(1,b = 10)

def general(*args, **kwargs):
    print(args)
    print(kwargs)

general(1,c=11)

(1,)
{'c': 11}

def general(a=10,b=11):
    print(a)
    print(b)

general(1,2)

1
2

list(generate(10))

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

a = 10
def a_function(a=11):
    print(a)
    
a_function()

11

Fibonacci Series

def fibonacci(n):
    if n <= 1:
        return n
    else:
        return fibonacci(n-1) + fibonacci(n - 2)
    
fibonacci(10)

55

Exceptions

try:
    raise SystemExit
except Exception as e:
    print("This was the problem:  {}".format(e))

An exception has occurred, use %tb to see the full traceback.
SystemExit

/Users/smhuda/opt/anaconda3/lib/python3.8/site-packages/IPython/core/interactiveshell.py:3445: UserWarning: To exit: use 'exit', 'quit', or Ctrl-D.
  warn("To exit: use 'exit', 'quit', or Ctrl-D.", stacklevel=1)

try:
    raise ValueError("Value wrong")
except ValueError as e:
    print("This was a value error")
except:
    print("This never ecxecutes")

This was a value error

try:
    raise TypeError("Value wrong")
except ValueError as e:
    print("This was a value error")
except:
    print("This never ecxecutes")

This never ecxecutes