In [ ]:
import typing

def leibnizPi(cb: typing.Callable) -> float:
    """
    Return an approximation of pi. Returns the approximation for which cb returns True.
    """
    # 4/1 - 4/3 + 4/5 ...
    pi = 0.0
    den = 1
    sign = 1
    while True: # while not cb(pi):
        pi = pi + sign*4/den
        den = den + 2
        sign = sign * -1
        if cb(pi):
            return pi
        
def closeEnoughPi(pi: float) -> bool:
    return pi > 3.141 and pi < 3.142

def notCloseEnoughPi(pi: float) -> bool:
    return pi > 3 and pi < 4

print(leibnizPi(notCloseEnoughPi))

3.466666666666667
In [ ]:
for c in "Hello, world!":
    print(c)

H
e
l
l
o
,
 
w
o
r
l
d
!
In [ ]:
print("hello, world!"[1])
print(range(1, 10)[2])

e
3
In [ ]:
print(len("hello"))
print("hello"[4])

s = "Hello, world!"
for i in range(len(s)):
    print(s[i])

5
o
H
e
l
l
o
,
 
w
o
r
l
d
!
In [ ]:
x = "Hello, world!"
print(x[1])
x[1] = "u"

<cell>3: error: Unsupported target for indexed assignment ("str")  [index]

e

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Input In [19], in <cell line: 3>()
      1 x = "Hello, world!"
      2 print(x[1])
----> 3 x[1] = "u"

TypeError: 'str' object does not support item assignment
In [ ]:
x = [2, 4, 6, 0, 1]
y = [2]
#z = []
print(x[2])

6
In [ ]:
def averageOf(l: list[float]) -> float:
    """
    Returns the average (arithmetic mean) of the values in the list l.
    """
    sum = 0.0
    for val in l:
        sum = sum + val
    return sum / len(l)

print(averageOf([2, 4, 6, 0, 1]))

2.6
In [ ]:
x[False]
Out[ ]:
2
In [ ]:
import typing

def contains(
    haystack: typing.Sequence,
    needle: typing.Any
) -> bool:
    """
    Returns True if the value needle is in the sequence haystack, False otherwise.
    """
    for val in haystack:
        if val == needle:
            return True
    return False

x = [2, 4, 6, 0, 1]
print(contains(x, 3))
print(3 in x)
print("e" in "hello")

False
False
True
In [ ]:
x = [2, 4, 6, 0, 1]
print(x)
x[1] = 8
print(x)
x.append(42)
print(x)

[2, 4, 6, 0, 1]
[2, 8, 6, 0, 1]
[2, 8, 6, 0, 1, 42]
In [ ]:
def runningAverage(l: list[float]) -> float:
    """
    Returns the average (arithmetic mean) of the values in the list l,
    while also replacing the values in the list with their running average.
    """
    sum = 0.0
    for idx in range(len(l)):
        sum = sum + l[idx]
        l[idx] = sum / (idx+1)
    return sum / len(l)

x = [2.0, 4.0, 6.0, 0.0, 1.0]
print(x)
print(runningAverage(x))
print(x)

[2.0, 4.0, 6.0, 0.0, 1.0]
2.6
[2.0, 3.0, 4.0, 3.0, 2.6]