Week 1 Videos#

list vs tuple vs set vs dict vs range#

mylist = [3,1,4,1,5,9]

type(mylist)

list

mytuple = (3,1,4,1,5,9)

type(mytuple)

tuple

tup2 = tuple(mylist)

tup2

(3, 1, 4, 1, 5, 9)

mytuple == tup2

True

mylist[2]

4

mytuple[2]

4

mylist.append(20.4)

mylist

[3, 1, 4, 1, 5, 9, 20.4]

mytuple.append(20.4)

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
Cell In [12], line 1
----> 1 mytuple.append(20.4)

AttributeError: 'tuple' object has no attribute 'append'

mytuple.append(3)

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
Cell In [13], line 1
----> 1 mytuple.append(3)

AttributeError: 'tuple' object has no attribute 'append'

myset = {3,1,4,1,5,9}

myset[2]

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In [15], line 1
----> 1 myset[2]

TypeError: 'set' object is not subscriptable

myset

{1, 3, 4, 5, 9}

myset2 = {3,1,[2,1,5]}

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In [17], line 1
----> 1 myset2 = {3,1,[2,1,5]}

TypeError: unhashable type: 'list'

myset2 = {3,1,(2,1,5)}

myset2

{(2, 1, 5), 1, 3}

len(myset2)

3

d = {3:0, 1:5, 4:10, 1:2}

d

{3: 0, 1: 2, 4: 10}

d[2]

---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
Cell In [23], line 1
----> 1 d[2]

KeyError: 2

d[4]

10

d[(2,10)] = "Chris"

d

{3: 0, 1: 2, 4: 10, (2, 10): 'Chris'}

d[[1,10]] = "Davis"

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In [27], line 1
----> 1 d[[1,10]] = "Davis"

TypeError: unhashable type: 'list'

d["4"] = [1,10]

d

{3: 0, 1: 2, 4: 10, (2, 10): 'Chris', '4': [1, 10]}

r = range(10)

r

range(0, 10)

list(r)

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

y = range(3,20,5)

tuple(y)

(3, 8, 13, 18)

list(range(3,23,5))

[3, 8, 13, 18]

range(0,10,0.1)

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In [36], line 1
----> 1 range(0,10,0.1)

TypeError: 'float' object cannot be interpreted as an integer

for loops#

  • Print the string "Hello, world" 8 times.

for i in range(8):
    print("Hello, world")

Hello, world
Hello, world
Hello, world
Hello, world
Hello, world
Hello, world
Hello, world
Hello, world

Let mylist = [3,1,4,1,-5,-9,2].

  • Print the squares of each element in mylist.

mylist = [3,1,4,1,-5,-9,2]

for i in range(7):
    print(mylist[i]**2)

9
1
16
1
25
81
4

for i in range(len(mylist)):
    print(mylist[i]**2)

9
1
16
1
25
81
4

for x in mylist:
    print(x**2)

9
1
16
1
25
81
4

  • Print the squares of the positive elements in mylist.

mylist

[3, 1, 4, 1, -5, -9, 2]

for x in mylist:
    if x > 0:
        print(x**2)

9
1
16
1
4

  • Make a new list containing x-2 for each element x in mylist.

newlist = []
for x in mylist:
    newlist.append(x-2)

newlist

[1, -1, 2, -1, -7, -11, 0]

Functions in Python#

def f(x):
    return x**2 - 5

f(7)

44

def g(x):
    print(x**2 - 5)

g(7)

44

y = f(7)

z = g(7)

44

y

44

z

z+2

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In [9], line 1
----> 1 z+2

TypeError: unsupported operand type(s) for +: 'NoneType' and 'int'

type(z)

NoneType

def check(x,y):
    z = x + 2*y
    if z > 10:
        return z
    elif z > 5:
        return 2*z
    else:
        return "Choose bigger numbers"

check(2,1)

'Choose bigger numbers'

check(2,2)

12

x

---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
Cell In [14], line 1
----> 1 x

NameError: name 'x' is not defined

y

44

f2 = lambda w: w**2 - 5

f2(10)

95
Created in deepnote.com Created in Deepnote