Jupyter Notebook: Python Advanced

Jupyter Notebook Explanation

blah blah

print('hello world')

hello world

answer = 42

print(answer)

42

Python Basics Recap

i = 42

type(i)

int

i = '42'

type(i)

str

def foo():
    print('hello')

type(foo)

function

foo = i

print(foo)

42

class Foo:
    def foo(self):
        print('foo hier')

f = Foo()

f.foo()

foo hier

type(f)

__main__.Foo

type(Foo)

type

dir(Foo)

['__class__',
 '__delattr__',
 '__dict__',
 '__dir__',
 '__doc__',
 '__eq__',
 '__format__',
 '__ge__',
 '__getattribute__',
 '__gt__',
 '__hash__',
 '__init__',
 '__init_subclass__',
 '__le__',
 '__lt__',
 '__module__',
 '__ne__',
 '__new__',
 '__reduce__',
 '__reduce_ex__',
 '__repr__',
 '__setattr__',
 '__sizeof__',
 '__str__',
 '__subclasshook__',
 '__weakref__',
 'foo']

Data Types

Integers and Floats

i = 42

type(i)

int

i = 2**64 - 1

i

18446744073709551615

i += 1

i

18446744073709551616

type(i)

int

if i == 2**64-1:
    print('jessas!')

i = 2

f = 42.666

type(f)

float

i + f

44.666

type(i)

int

i.__add__(f)

NotImplemented

f.__add__(i)

44.666

i - f

-40.666

i.__sub__(f)

NotImplemented

f.__rsub__(i)

-40.666

10**1000

10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

Datatype Conversions

class Foo:
    def foo(self):
        print('foo hier')

f = Foo()

type(f)

__main__.Foo

s = '42'

type(s)

str

i = int(s)

i

42

str(i)

'42'

type(i)

int

float('42.666')

42.666

try:
    int('abc')
except ValueError as e:
    print(type(e), e)

<class 'ValueError'> invalid literal for int() with base 10: 'abc'

int('abc', 16)

2748

int(42.666)

42

try:
    int('42.666')
except ValueError as e:
    print(type(e), e)

<class 'ValueError'> invalid literal for int() with base 10: '42.666'

s = 'hello'

s += ' world'

s

'hello world'

i

42

print(i)

42

type(f)

__main__.Foo

print_s = str(i)

print_s

'42'

print(print_s)

42

str(i)

'42'

i.__str__()

'42'

class Person:
    def __init__(self, firstname, lastname):
        self.firstname = firstname
        self.lastname = lastname

joerg = Person('Joerg', 'Faschingbauer')

type(joerg)

__main__.Person

print(joerg)

<__main__.Person object at 0x7f0b165fdf00>

class Person:
    def __init__(self, firstname, lastname):
        self.firstname = firstname
        self.lastname = lastname
    def __str__(self):
        return f'{self.firstname} {self.lastname}'

joerg = Person('Joerg', 'Faschingbauer')

print(joerg)

Joerg Faschingbauer

Strings: String Methods, Docstrings, …

s = 'hello'

s

'hello'

s = "hello"

s

'hello'

s = "hello \"world\""

s

'hello "world"'

s = 'hello "world"'

s

'hello "world"'

dos_path = "C:\Dokumente\neues zeug"

print(dos_path)

C:\Dokumente
eues zeug

dos_path = "C:\\Dokumente\\neues zeug"

print(dos_path)

C:\Dokumente\neues zeug

dos_path = r"C:\Dokumente\neues zeug"

print(dos_path)

C:\Dokumente\neues zeug

Docstrings, Multiline Strings

s = '''erste zeile
zweite zeile
'''

print(s)

erste zeile
zweite zeile

def foo():
    '''
    Das ist eine Funktion, von der
    keiner weiss, was sie tut, weil sie keinen
    vernuenftigen Namen hat.
    '''
    return 666

foo

<function __main__.foo()>

foo.__doc__

'\n    Das ist eine Funktion, von der\n    keiner weiss, was sie tut, weil sie keinen\n    vernuenftigen Namen hat.\n    '

help(foo)

Help on function foo in module __main__:

foo()
    Das ist eine Funktion, von der
    keiner weiss, was sie tut, weil sie keinen
    vernuenftigen Namen hat.

class Foo:
    '''
    Das ist eine Klasse, von der
    keiner weiss, was sie tut, weil sie keinen
    vernuenftigen Namen hat.'''

    def foo(self):
        '''
        Das ist eine Funktion, von der
        keiner weiss, was sie tut, weil sie keinen
        vernuenftigen Namen hat.'''
        return 666

help(Foo)

Help on class Foo in module __main__:

class Foo(builtins.object)
 |  Das ist eine Klasse, von der
 |  keiner weiss, was sie tut, weil sie keinen
 |  vernuenftigen Namen hat.
 |
 |  Methods defined here:
 |
 |  foo(self)
 |      Das ist eine Funktion, von der
 |      keiner weiss, was sie tut, weil sie keinen
 |      vernuenftigen Namen hat.
 |
 |  ----------------------------------------------------------------------
 |  Data descriptors defined here:
 |
 |  __dict__
 |      dictionary for instance variables (if defined)
 |
 |  __weakref__
 |      list of weak references to the object (if defined)

s = 'hello'
s1 = 'world'

s + ' ' + s1

'hello world'

try:
    42 < s
except Exception as e:
    print(type(e), e)

<class 'TypeError'> '<' not supported between instances of 'int' and 'str'

s = 'mississippi'

s.count('ss')

2

s.find('ss')

2

s.find('ss', 3)

5

s.find('xxx')

-1

s.index('ss')

2

try:
    s.index('xxx')
except Exception as e:
    print(type(e), e)

<class 'ValueError'> substring not found

s.center(50)

'                   mississippi                    '

Python Documentation Overview: https://docs.python.org/3/

class str(object='')

str()

''

str('')

''

class str(object=b'', encoding='utf-8', errors='strict')

str(b'J\xf6rg', encoding='iso-8859-1')

'Jörg'

Compound Datatypes

List

l = [1,2,3]

l.append(4)

l

[1, 2, 3, 4]

l.append('five')

l

[1, 2, 3, 4, 'five']

del l[0]

l

[2, 3, 4, 'five']

try:
    del l[100]
except Exception as e:
    print(type(e), e)

<class 'IndexError'> list assignment index out of range

l

[2, 3, 4, 'five']

l.pop(1)

3

l

[2, 4, 'five']

l

[2, 4, 'five']

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

l[1:4]

[2, 3, 4]

l[1:4] = []

l

[1, 5]

l[1:1]

[]

l[1:1] = [2,3,4]

l

[1, 2, 3, 4, 5]

l[1:4] = ['zwei', 'drei']

l

[1, 'zwei', 'drei', 5]

l[0:0] = [-2, -1, 0]

l

[-2, -1, 0, 1, 'zwei', 'drei', 5]

l.insert(0, -3)

l

[-3, -2, -1, 0, 1, 'zwei', 'drei', 5]

'zwei' in l

True

5 in l

True

666 in l

False

Set

s = {1,2,3,4}

3 in s

True

s.add(666)

s

{1, 2, 3, 4, 666}

s.remove(2)

s

{1, 3, 4, 666}

s1 = {1, 2, 3, 4}

s2 = {3, 4, 5, 6}

s1 | s2

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

s1 - s2

{1, 2}

s1 ^ s2

{1, 2, 5, 6}

s1 & s2

{3, 4}

dir(s1)

['__and__',
 '__class__',
 '__class_getitem__',
 '__contains__',
 '__delattr__',
 '__dir__',
 '__doc__',
 '__eq__',
 '__format__',
 '__ge__',
 '__getattribute__',
 '__gt__',
 '__hash__',
 '__iand__',
 '__init__',
 '__init_subclass__',
 '__ior__',
 '__isub__',
 '__iter__',
 '__ixor__',
 '__le__',
 '__len__',
 '__lt__',
 '__ne__',
 '__new__',
 '__or__',
 '__rand__',
 '__reduce__',
 '__reduce_ex__',
 '__repr__',
 '__ror__',
 '__rsub__',
 '__rxor__',
 '__setattr__',
 '__sizeof__',
 '__str__',
 '__sub__',
 '__subclasshook__',
 '__xor__',
 'add',
 'clear',
 'copy',
 'difference',
 'difference_update',
 'discard',
 'intersection',
 'intersection_update',
 'isdisjoint',
 'issubset',
 'issuperset',
 'pop',
 'remove',
 'symmetric_difference',
 'symmetric_difference_update',
 'union',
 'update']

Dictionary

d = {1: 'eins', 2: 'zwei'}

type(d)

dict

d[1]

'eins'

try:
    d[3]
except Exception as e:
    print(type(e), e)

<class 'KeyError'> 3

3 in d

False

2 in d

True

d.get(2)

'zwei'

v = d.get(2)

v

'zwei'

v = d.get(3)

print(v)

None

type(v)

NoneType

if d.get(3) is None:
    v = 'drei'
else:
    v = d.get(3)

print(v)

drei

v = d.get(3, 'drei')
print(v)

drei

d[3] = 'drei'

d[3]

'drei'

if 4 in d:
    v = d[4]
else:
    d[4] = 'vier'
    v = d[4]

v = d.setdefault(5, 'fuenf')
print(v)

fuenf

Iteration

l = [1, 2, 3, 4]

for element in l:
    print(element)

1
2
3
4

s = {1,2,3,4}

for element in s:
    print(element)

1
2
3
4

d = {1:'eins', 2:'zwei', 3: 'drei'}

for element in d:
    print(element)

1
2
3

for element in d.keys():
    print(element)

1
2
3

for element in d.values():
    print(element)

eins
zwei
drei

for element in d.items():
    print(element)

(1, 'eins')
(2, 'zwei')
(3, 'drei')

for element in d.items():
    k = element[0]
    v = element[1]
    print(k, v)

1 eins
2 zwei
3 drei

for k, v in d.items():
    print(k, v)

1 eins
2 zwei
3 drei

Tuple unpacking

l = [3, 4, 5]
a, b, c = l

print(a, b, c)

3 4 5

l = [1, 2, 3, 4]

try:
    a, b, c = l
except Exception as e:
    print(type(e), e)

<class 'ValueError'> too many values to unpack (expected 3)

a, b, *rest = l

print(a, b)

1 2

rest

[3, 4]

assert

def foo(bar):
    'Compute a foo from a bar string'
    assert type(bar) is str
    return bar*5

foo('hallo')

'hallohallohallohallohallo'

try:
    foo([1, 2, 3])
except AssertionError:   # <--- DON'T DO THIS! NEVER EVER!!
    pass

References, (Im)mutability

a = 42

id(a)

139685905188368

b = a

id(b)

139685905188368

a += 1

a

43

b

42

id(b)

139685905188368

id(a)

139685905188400

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

a is b

True

id(a) == id(b)

True

c = a[:]

c is a

False

l1 = [1, [2, 3, 4], 5]

len(l1)

3

l2 = l1[:]

l2 is l1

False

l1

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

l2

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

l1.append(6)

l1

[1, [2, 3, 4], 5, 6]

l2

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

l1[1].append(666)

l1

[1, [2, 3, 4, 666], 5, 6]

l2

[1, [2, 3, 4, 666], 5]

Deep copy

import copy

l1 = [1, [2,3,4], 5]

l2 = copy.deepcopy(l1)

l1 is l2

False

l1[1] is l2[1]

False

class Person:
    def __init__(self, firstname, lastname):
        self.firstname = firstname
        self.lastname = lastname

joerg = Person('Joerg', 'Faschingbauer')

joerg

<__main__.Person at 0x7f0b14487be0>

joerg.__dict__

{'firstname': 'Joerg', 'lastname': 'Fasschingbauer'}

Strings are immutable

s1 = 'hello'

id(s1)

139685602274352

s1 += ' '

id(s1)

139685561461616

Lists are mutable

l = [1,2,3]

id(l)

139685561690240

l.append(4)

id(l)

139685561690240

And tuples?

t = (1, 2, 3)

id(t)

139685561316032

t += (4, 5)

id(t)

139685595970464

try:
    t.append(6)
except Exception as e:
    print(type(e), e)

<class 'AttributeError'> 'tuple' object has no attribute 'append'

And dictionary? -> frozendict

d = {1:'eins', 2:'zwei'}

id(d)

139685561151488

d.setdefault(3, 'three')

'three'

id(d)

139685561151488

Iteration, Generators, Iterator Protocol

l = [0, 1, 2]

print(l)

[0, 1, 2]

for element in l:
    print(element)

0
1
2

for element in range(3):
    print(element)

0
1
2

r = range(3)

for element in r:
    print(element)

0
1
2

print(r)

range(0, 3)

range(3*10**7)

range(0, 30000000)

for element in l:
    print(element)

0
1
2

Iterator Protocol

l

[0, 1, 2]

it = iter(l)

type(it)

list_iterator

next(it)

0

next(it)

1

next(it)

2

try:
    next(it)
except Exception as e:
    print(type(e), e)

<class 'StopIteration'>

r = range(3)

it = iter(r)

next(it)

0

next(it)

1

next(it)

2

try:
    next(it)
except Exception as e:
    print(type(e), e)

<class 'StopIteration'>

Enter yield

def my_iterable():
    print('before 0')
    yield 0
    print('before 1')
    yield 1
    print('before 2')
    yield 2
    print('done')

m = my_iterable()

type(m)

generator

it = iter(m)

next(it)

before 0

0

next(it)

before 1

1

next(it)

before 2

2

try:
    next(it)
except Exception as e:
    print(type(e), e)

done
<class 'StopIteration'>

m = my_iterable()

for element in m:
    print(element)

0
1
2

def even_numbers(start, end):
    run = start
    while run < end:
        if run % 2 == 0:
            yield run
        run += 1

for element in even_numbers(5, 20):
    print(element)

6
8
10
12
14
16
18

AAARGHHH

def f(a, b):
    print(a, b)

f(1, 2)

1 2

l = [1,2]

f(l[0], l[1])

1 2

f(*l)

1 2

def f(*args):
    print(args)

f(1, 2)

(1, 2)

f(1, 2, 3)

(1, 2, 3)

t = (1,2,3)

len(t)

3

t.__len__()

3

def my_print(*args):
    my_args = ('hallo, ',) + args
    print(*my_args)

my_print(1, 2)

hallo,  1 2

Comprehensions

List Comprehension

r = range(5)

squares = []
for i in r:
    squares.append(i**2)

squares

[0, 1, 4, 9, 16]

squares = [i**2 for i in range(5)]

squares

[0, 1, 4, 9, 16]

even_squares = [i**2 for i in range(10) if i%2 == 0]

even_squares

[0, 2, 4, 6, 8]

Generator Expresssions

def squares_fun():
    sqs = []
    for i in range(5):
        sqs.append(i**2)
    return sqs
squares = squares_fun()

squares

[0, 1, 4, 9, 16]

squares = [i**2 for i in range(5)]

squares

[0, 1, 4, 9, 16]

def squares_gen():
    for i in range(5):
        yield i**2
squares = squares_gen()

squares

<generator object squares_gen at 0x7f0aefb94f20>

for i in squares:
    print(i)

squares = (i**2 for i in range(5))

squares

<generator object <genexpr> at 0x7f0aefb955b0>

for i in squares:
    print(i)

0
1
4
9
16

for i in squares:
    print(i)

squares = (i**2 for i in range(5))

try:
    squares[3]
except Exception as e:
    print(type(e), e)

<class 'TypeError'> 'generator' object is not subscriptable

squares_list = list(squares)

squares_list

[0, 1, 4, 9, 16]

list('abc')

['a', 'b', 'c']

for c in 'abc':
    print(c)

a
b
c

Dictionary Comprehension

d = {
    1: 1,
    2: 4,
    3: 9,
    # ...
}

d = {i: i**2 for i in range(10)}

d

{0: 0, 1: 1, 2: 4, 3: 9, 4: 16, 5: 25, 6: 36, 7: 49, 8: 64, 9: 81}

type(d)

dict

Set Comprehension

s = {1, 4, 9, 16,} # ...

s = {i**2 for i in range(10)}

s

{0, 1, 4, 9, 16, 25, 36, 49, 64, 81}

set('foobar')

{'a', 'b', 'f', 'o', 'r'}

set(['foo', 'bar'])

{'bar', 'foo'}

Trailing comma? …

t = (1, 2, 3)

type(t)

tuple

t = (666)

type(t)

int

t = (42,)

type(t)

tuple

t

(42,)

len(t)

1

t.__len__()

1

eval()

expr_str = '[1,2,3]'

type(expr_str)

str

expr = eval(expr_str)

type(expr)

list

expr

[1, 2, 3]

Functional Tools

enumerate()

l = ['Joerg', 'Caro', 'Johanna', 'Philipp']
i = 0
for element in l:
    print(i, element)
    i += 1

0 Joerg
1 Caro
2 Johanna
3 Philipp

for i, element in enumerate(l):
    print(i, element)

0 Joerg
1 Caro
2 Johanna
3 Philipp

map(), filter()

[i**2 for i in range(5)]

[0, 1, 4, 9, 16]

def sq(i): return i**2
for num in map(sq, range(5)):
    print(num)

0
1
4
9
16

for num in map(lambda i: i**2, range(5)):
    print(num)

0
1
4
9
16

Same with a custom generator expression

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

0
1
4
9
16

filter()

def even(i):
    return i%2 == 0

for num in filter(even, range(5)):
    print(num)

0
2
4

for num in filter(lambda i: i%2 == 0, range(5)):
    print(num)

0
2
4

for num in (i for i in range(5) if i%2 == 0):
    print(num)

0
2
4

Data Science

import pandas as pd

import numpy as np

df = pd.read_csv('data.csv', skiprows=1, sep=';')

df

	timestamp	hz2	hz3_5
0	2023-10-26:14:46:04	0.000566	0.000729
1	2023-10-26:14:46:04	0.132363	0.229977
2	2023-10-26:14:46:04	0.260597	0.444942
3	2023-10-26:14:46:04	0.385433	0.638212
4	2023-10-26:14:46:04	0.502710	0.796519
...	...	...	...
507	2023-10-26:14:46:09	-0.936250	-0.972326
508	2023-10-26:14:46:09	-0.974442	-0.999992
509	2023-10-26:14:46:09	-0.995683	-0.973719
510	2023-10-26:14:46:09	-0.999245	-0.895850
511	2023-10-26:14:46:09	-0.985202	-0.768778

512 rows × 3 columns

points = np.arange(stop=512*0.001, step=0.001)

df['timestamp'] = points

df

	timestamp	hz2	hz3_5
0	0.000	0.000566	0.000729
1	0.001	0.132363	0.229977
2	0.002	0.260597	0.444942
3	0.003	0.385433	0.638212
4	0.004	0.502710	0.796519
...	...	...	...
507	0.507	-0.936250	-0.972326
508	0.508	-0.974442	-0.999992
509	0.509	-0.995683	-0.973719
510	0.510	-0.999245	-0.895850
511	0.511	-0.985202	-0.768778

512 rows × 3 columns

import matplotlib.pyplot as plt

%matplotlib inline

plt.plot(df['timestamp'], df['hz2'])

[<matplotlib.lines.Line2D at 0x7f0ad44b8f70>]

plt.plot(df['timestamp'], df['hz3_5'])

[<matplotlib.lines.Line2D at 0x7f0ad23371f0>]