Lesson Notes
Fstrings in Python allow you to easily use variables in a string
Without fstrings
num = 5
t = range(10)
mystr = "This is a string with a " + str(num) + " and " + str(t)
print(mystr)
with fstrings
num = 5
t = range(10)
mystr = f"This is a string with a {num} and {t}"
print(mystr)
print(f"This is another fstring: {1 > 0}")
{``}f at the beginning of the stringHow is Python converting binary data to a string?
var = 2
print(var)
2 = binary value ...0010
Python uses __dunders__ to manipulate object data. Any method surrounded by __ is referered to as a dunder in python.
Dunders are used by Python, not by the programmers. In the same way someone wrote print() for you to use, you can write dunders for Python to use.
Most dunder methods have a default implementaion that you can override. For example, __init__ is optional because it has already been implemented for you as an empty method:
class Num:
def __init__(self):
pass
class Num:
def __init__(self):
self.num = 5
n = Num()
print(n)
print(n.num)
The __str__ dunder allows you to overwrite what prints when you print your object
__str__ must return a string objectselfDON'T:
__str__ method__str__ explicitly,
str(var)f'{var}'__str__class Num:
def __init__(self, x = 0):
self.num = x
def __str__(self):
return str(self.num)
n = Num(9)
print(n)
__str__class Point:
def __init__(self, x=0, y=0, color="red"):
self.x = x
self.y = y
if color == "green":
print("You are a bad person")
color = "blue"
self.color = color
def set_to_complimentary_color(self):
red_comp = 255- self.color[0]
blue_comp = 255- self.color[1]
green_comp = 255- self.color[2]
self.color = [red_comp, blue_comp, green_comp]
class Graph:
def __init__(self, title="My Graph"):
self.points = []
self.title = title
def add_point(self, p):
self.points.append(p)
def __str__(self):
graph_str = ""
#...
return graph_str
def main():
g = Graph()
print(g)
p = Point(5, 2)
p2 = Point(3,4)
g.add_point(p)
g.add_point(p2)
print(g)
main()
Try writing the
__str__method for theGraphclass...
def __str__(self):
points_list = []
for p in self.points:
points_list.append(f’({p.x}, {p.y})')
return ", ".join(points)