9 Python-Programmierkenntnisse, die Anfänger von erfahrenen unterscheiden

Anfänger oder erfahren?

• Problemlösung und die Kunst, Fragen zu stellen
• Verstehen, warum Code funktioniert (oder nicht)
• Arbeite mit Strings
• Mit Listen arbeiten
• Schleifen verwenden
• Verwenden von Funktionen (und korrekter Terminologie)
• Objekt orientierte Programmierung
• Respekt für PEP

Problemlösung und die Kunst, Fragen zu stellen

Problem xy

"Ich muss die letzten drei Zeichen in einer Zeichenfolge erhalten."
"Nein, das braucht es nicht! Sie müssen die Dateierweiterung erhalten. “

def extract_ext(filename):
    return filename[-3:]
print (extract_ext('photo_of_sasquatch.png'))
>>> png

def extract_ext(filename):
    return filename.split('.')[-1]
print (extract_ext('photo_of_sasquatch.png'))
print (extract_ext('photo_of_lochness.jpeg'))
>>> png
>>> jpeg

Verstehen, warum Code funktioniert (oder nicht)

Arbeite mit Strings

word = 'supergreat'
print (f'{word[0]}') 
>>> s
print (f'{word[0:5]}')
>>> super

Mit Listen arbeiten

my_list = ['a' , 'b' , 'n' , 'x' , 1 , 2 , 3, 'a' , 'n' , 'b']
for item in my_list:
    print (f'current item: {item}, Type: {type(item)}')

print (my_list.sort())

my_list = ['a' , 'b' , 'n' , 'x' , 1 , 2 , 3 , 'a' , 33.3 , 'n' , 'b']
number_list = []
string_list = []
for item in my_list:
    print (f'current item: {item}, Type: {type(item)}')
    if not isinstance(item,str):
        number_list.append(item)
    else:
        string_list.append(item)
my_list = string_list

my_list = [letter for letter in my_list if isinstance(letter,str)]

def get_numbers(input_char):
    if not isinstance(input_char,str):
        return True
    return False

my_list = [1,2,3,'a','b','c']
check_list = filter(get_numbers, my_list)
for items in check_list:
    print(items)

• Liste (oder Zeile) umdrehen:

names = ['First' , 'Middle' , 'Last']
print(names[::-1])
>>> ['Last', 'Middle', 'First']

• Listenelemente kombinieren:

names = ['First' , 'Middle' , 'Last']
full_name = ' '.join(names)
print(f'Full Name:\n{full_name}')
>>> First Middle Last

Schleifen verwenden

greek_gods = ['Zeus' , 'Hera' , 'Poseidon' , 'Apollo' , 'Bob']
for index in range(0,len(greek_gods)):
    print (f'at index {index} , we have : {greek_gods[index]}')

for name in greek_gods:
    print (f'Greek God: {name}')

for index, name in enumerate(greek_gods):
    print (f'at index {index} , we have : {name}')

Verwenden von Funktionen (und korrekter Terminologie)

def print_list(input_list):
    for each in input_list:
        print(f'{each}')
    print() #just to separate output
greek_gods = ['Zeus' , 'Hera' , 'Poseidon' , 'Apollo' , 'Bob']
grocery_list = ['Apples' , 'Milk' , 'Bread']
print_list(greek_gods)
print_list(grocery_list)
print_list(['a' , 'b' , 'c'])

def reverse_list(list_input):
    return list_input[::-1]
my_list = ['a', 'b' , 'c']
print (reverse_list(my_list))
>>> ['c', 'b', 'a']

Objekt orientierte Programmierung

class Student():
    def __init__(self,name):
        self._name = name
        self._subject_list = []

student1 = Student('Martin Aaberge')

student2 = Student('Ninja Henderson')

class Student():
    def __init__(self,name):
        self._name = name
        self._subject_list = []
    def add_subject(self, subject_name):
        self._subject_list.append(subject_name)
    def get_student_data(self):
        print (f'Student: {self._name} is assigned to:')
        for subject in self._subject_list:
            print (f'{subject}')
        print()

#create students:
student1 = Student('Martin Aaberge')
student2 = Student('Heidi Hummelvold')
#add subjects to student1
student1.add_subject('psychology_101')
student1.add_subject('it_security_101')
#add subject to student2
student2.add_subject('leadership_101')
#print current data on students
student1.get_student_data()
student2.get_student_data()

from student import Student
student1 = Student('Martin')
student1.add_subject('biomechanics_2020')
student1.get_student_data()

Respektiere Pep

chocolate_cake = 'yummy'

chocolateCake = 'Yummy'

Fazit