Python2019/labs03/Podstawy, cz. 3.ipynb

Python: podstawy, cz. 3 (ostatnia)

 

9 lutego 2019

Kilka uwag do zadania domowego:

def even_elements(list):
    output = []
    for element in range(len(list)):
        if element % 2 == 0:
            output.append(list[element])
    return output

def even_elements(elems):
    output = []
    for element in range(len(elems)):
        if element % 2 == 0:
            output.append(elems[element])
    return output

def leet_speak(text):
    text2 = ""
    i = 0
    suma = 0
    for e in text:
        if text[i] == "e":
            text2 = text2 + "3"
            i = i + 1
        else:
            if text[i] == "l":
                text2 = text2 + "1"
                i = i + 1
            else:
                if text[i] == "o":
                    text2 = text2 + "0"
                    i = i + 1
                else:
                    if text[i] == "t":
                        text2 = text2 + "7"
                        i = i + 1
                    else:
                        text2 = text2 + text[i]
                        i = i + 1
    return (text2)

def leet_speak(text):
    text2 = ""
    i = 0
    suma = 0
    for e in text:
        if text[i] == "e":
            text2 = text2 + "3"
        elif text[i] == "l":
            text2 = text2 + "1"
        elif text[i] == "o":
            text2 = text2 + "0"
        elif text[i] == "t":
            text2 = text2 + "7"
        else:
            text2 = text2 + text[i]
        i = i + 1
    return (text2)

Do tej pory:

• podstawowe typy danych
• pętla for i wyrażenie warunkowe if
• listy, słowniki
• funkcje

Wbudowane funkcje w Pythona

elems = [1, 5, 10, 18, 2]
print(min(elems), max(elems), sum(elems))

1 18 36

elems = [1, 5, 10, 18, 2]
for idx, elem in enumerate(elems):
    print("Index:", idx, "wartość:", elem)

for idx in range(len(elems)):
    elem = elems[idx]
    print("Index:", idx, "wartość:", elem)

Index: 0 wartość: 1
Index: 1 wartość: 5
Index: 2 wartość: 10
Index: 3 wartość: 18
Index: 4 wartość: 2
Index: 0 wartość: 1
Index: 1 wartość: 5
Index: 2 wartość: 10
Index: 3 wartość: 18
Index: 4 wartość: 2

ages = [1, 5, 10, 18, 2, 1]
names = ["Alicja", "Beata", "Cecylia", "Danuta", "Eryka"]
for age, name in zip(ages, names):
    print(name, "lat", age, ".")

Alicja lat 1 .
Beata lat 5 .
Cecylia lat 10 .
Danuta lat 18 .
Eryka lat 2 .

def circle_length(radius):
    return 2 * 3.14 * radius
radii = [3, 4, 5, 6]

results = []
for r in radii:
    results.append(circle_length(r))

results = list(map(circle_length, radii))
print(results)

[18.84, 25.12, 31.400000000000002, 37.68]

radii = [3, 4, 5, 6]

f = lambda radius: 2 * 3.14 * radius
print(f(2))
results = map(f, radii)
print(list(results))

12.56
[18.84, 25.12, 31.400000000000002, 37.68]

Funkcje lambda

• składnia: lambda nazwa_zmiennej: zwracana_wartość

code = input("Co mam zrobić?\n")
eval(code)

Co mam zrobić?
print("ala ma kota.")
ala ma kota.

Listy składane

elems = [10, 50, 40, 30, 100, 19990]
lens = []
for elem in elems:
    lens.append(len(str(elem)))
print(lens)

[2, 2, 2, 2, 3, 5]

elems = [10, 50, 40, 30, 100, 19990]
lens = [len(str(elem)) for elem in elems]
print(lens)

[2, 2, 2, 2, 3, 5]

elems = [10, 50, 40, 30, 100, 19990]
lens = [len(str(elem)) for elem in elems 
        if str(elem)[0] == '1']
print(lens)

[2, 3, 5]

elems = [10, 50, 40, 30, 100, 19990]
lens = [len(str(elem)) 
        if str(elem)[0] == '1' else 0
        for elem in elems]
print(lens)

[2, 0, 0, 0, 3, 5]

def times(elem, n=2):
    if isinstance(elem, list):
        return [times(item, n) for item in elem]
    elif isinstance(elem, float) or isinstance(elem, int):
        return elem * n
    else:
        raise ValueError("błąd")

print(times([5, 7, [8, 9.0]]), 2)

[10, 14, [16, 18.0]] 2

Formatowanie napisów

• procentowe formatowanie z Pythona 2
• metoda format
• f-stringi (Python 3.6)

imie = "Jan"
nazwisko = "Kowalski"
wiek = 34

full_name = imie + " " + nazwisko + ", lat " + str(wiek)
full_name = "%s %s, lat %d" % (imie, nazwisko, wiek)
print(full_name)

Jan Kowalski, lat 34

imie = "Jan"
nazwisko = "Kowalski"
wiek = 34

full_name = "{0} {0}, lat {2}".format(imie, nazwisko, wiek)
print(full_name)
full_name = f"{imie} {nazwisko}, lat {wiek}"
print(full_name)

Jan Kowalski, lat 34
Jan Kowalski, lat 34

OOP: Programowanie obiektowe

class Sentence:
    pass
sentence = Sentence()

class Sentence:
    def __init__(self, text):
        self.text = text
sentence = Sentence("This is a little test.")

sent_1 = Sentence("This is a little test.")
sent_2 = Sentence("This is a little test.")
print(sent_1 == sent_2)
print("text: {}".format(sent_1.text))

False
text: This is a little test.

class Sentence:
    def __init__(self, text):
        self.text = text
    def word_number(self):
        return len(self.text.split(' '))
    
    def is_question(self):
        return self.text[-1] == "?"
    
sent = Sentence("To jest test .")
print("Liczba słów: {}".format(sent.word_number()))

Liczba słów: 4

class Employee:
    def __init__(self, name, salary):
        self.name = name
        self.salary = salary
    def raise_salary(self, amount):
        self.salary += amount
        
employee = Employee("Franek", 6000)
employee.raise_salary(500)
print(employee.salary)

6500

class Manager(Employee):
    def __init__(self, name, salary, team):
        super().__init__(name, salary)
        self.team = team

man = Manager("Joanna", 6000, "super-team")