 # Python Basics

1. print(‘Hello world!’)
2. print(‘Spam and eggs…’)
3. 5 + 4 – 3
4. 2 * (3 + 4)
5. (-7 + 2) * (-4)
6. 11 / 0
7. 9.8765000
9.8765
8. 6 * 7.0
42.0
9. 9 ** (1/2)
3.0
10. (-7 + 2) * (-4)
11. 20 // 6
12. 1.25 % 0.5
13. “Python is fun!”
14. \n
15. print(“Hello\nWorld!”)
17. print(“First ” + “, ” + “second “)
18. “2” + “2”
19. 1 + ‘2’ + 3 + ‘4’
20. print(“spam” * 3)
21. 4 * ‘2’
22. ’17’ * ’87’
23. ‘pythonisfun’ * 7.0
24. int(“2”) + int(“3”)
25. (input(“Enter a number: “)) + (input(“Enter another number: “))
26. x = “This is a
>>> print(x + “!”)
27. del foo
28. x += 3
>>> print(x)
29. Control Structures
30. my_boolean = True
31. 7 > 5
True
32. 9 >= 9.0
True
33. if 10 > 5:
print(“10 greater than 5”)
34. num = 12
if num > 5:
print(“Bigger than 5”)
if num <=47:
print(“Between 5 and 47”)
35. x = 4
if x == 5:
print(“Yes”)
else:
print(“No”)
36. num = 7
if num == 5:
print(“Number is 5”)
else:
if num == 11:
print(“Number is 11”)
else:
if num == 7:
print(“Number is 7”)
else:
print(“Number isn’t 5, 11 or 7”)
37. num = 7
if num == 5:
print(“Number is 5”)
num == 11:
print(“Number is 11”)
num == 7:
print(“Number is 7”)
else:
print(“Number isn’t 5, 11 or 7”)
38. 1 != 1 and 2 == 2
False
39. 1 != 1 or 2 == 2
True
40. not 1 == 1
False
41. False == (False or True)
False
42. i = 1
while i <=5:
print(i)
i = i + 1
43. i = 0
while 1==1:
print(i)
i = i + 1
if i >= 5:
print(“Breaking”)
44. i = 0
while True:
i = i +1
if i == 2:
print(“Skipping 2”)
continue
if i == 5:
print(“Breaking”)

print(i)
45. number = 3
things = [““, 0, [1, 2, number], 4.56]
print(things)
print(things)
print(things)
46. str = “Hello world!”
print(str)
47. nums = [1, 2, 3]
print(nums + [4, 5, 6])
print(nums * 3)
Try It Yourself

Result:>>>
[1, 2, 3, 4, 5, 6]
[1, 2, 3, 1, 2, 3, 1, 2, 3]

48. words = [“spam”, “egg”, “spam”, “sausage”]
print(“spam” in words)
print(“egg” in words)
print(“tomato” in words)
49. nums = [1, 2, 3]
print(not 4 in nums)
print(4 not in nums)
print(not 3 in nums)
print(3 not in nums)
50. nums = [1, 2, 3]
nums.append(4)
print(nums)
51. nums = [1, 3, 5, 2, 4]
print(len(nums))
52. words = [“Python”, “fun”]
index = 1
words.insert(index, “is”)
print(words)
53. letters = [‘p’, ‘q’, ‘r’, ‘s’, ‘p’, ‘u’]
print(letters.index(‘r’))
print(letters.index(‘p’))
print(letters.index(‘z’))
Try It Yourself

Result:>>>
2
0
ValueError: ‘z’ is not in list

54. numbers = list(range(10))
print(numbers)
55. numbers = list(range(3, 8))
print(numbers)
print(range(20) == range(0, 20))Try It Yourself

Result:>>>
[3, 4, 5, 6, 7]

True

56. numbers = list(range(5, 20, 2))
print(numbers)
Try It Yourself

Result:>>>
[5, 7, 9, 11, 13, 15, 17, 19]

57. words = [“hello”, “world”, “spam”, “eggs”]
counter = 0
max_index = len(words) – 1while counter <= max_index:
word = words[counter]
print(word + “!”)
counter = counter + 1
58. words = [“hello”, “world”, “spam”, “eggs”]
for word in words:
print(word + “!”)
59. for i in range(5):
print(“hello!”)
Try It Yourself

Result:>>>
hello!
hello!
hello!
hello!
hello!
>>>

60. DRY
61. my_func():
print(“spam”)
print(“spam”)
print(“spam”)my_func()
62. print_with_exclamation(word):
print(word + “!”)print_with_exclamation(“spam”)
print_with_exclamation(“eggs”)
print_with_exclamation(“python”)
63. print_sum_twice(x, y):
print(x + y)
print(x + y)print_sum_twice(5, 8)
64. ():
+= 1
print()(7)
print()
65. max(x, y):
if x >=y:
return x
else:
return yprint(max(4, 7))
z = max(8, 5)
print(z)
total = x + y
67. x = 365
y = 7
# this is a commentprint(x % y) # find the remainder
# print (x // y)
# another comment
68. shout(word):
“””
Print a word with an
exclamation mark following it.
“””

print(word + “!”)shout(“spam”)
69. multiply(x, y):
return x * ya = 4
b = 7
operation = multiply
print(operation(a, b))
return x + y
do_twice(func, x, y):
return func(func(x, y), func(x, y))a = 5
71. import randomfor i in range(5):
value = random.randint(1, 6)
print(value)
72. from math import piprint(pi)
73. from math import sqrt as square_root
print(square_root(100))
74. Common exceptions:
ImportError: an import fails;
IndexError: a list is indexed with an out-of-range number;
NameError: an unknown  is used;
SyntaxError: the code can’t be parsed properly;
TypeError: a  is called on a value of an inappropriate type;
ValueError: a  is called on a value of the correct type, but with an inappropriate value.
75. try:
num1 = 7
num2 = 0
print (num1 / num2)
print(“Done calculation”)
except ZeroDivisionError:
print(“An error occurred”)
print(“due to zero division”)
76. try:
= 10
print( + “hello”)
print( / 2)
except ZeroDivisionError:
print(“Divided by zero”)
except (ValueError, TypeError):
print(“Error occurred”)
77. try:
word = “spam”
print(word / 0)
except:
print(“An error occurred”)
78. try:
print(1)
print(10 / 0)
except ZeroDivisionError:
print(unknown_var)
finally:
print(“This is executed last”)
79. name = “123”
raise NameError(“Invalid name!”)
80. try:
num = 5 / 0
except:
print(“An error occurred”)
raise
81. print(1)
assert 2 + 2 == 4
print(2)
assert 1 + 1 == 3
print(3)
82. temp = -10
assert (temp >= 0), “Colder than absolute zero!”
83. myfile = open(“filename.txt”)
84. # write mode
open(“filename.txt”, “r”)
open(“filename.txt”)

# binary write mode
open(“filename.txt”, “wb”)

85. file = open(“filename.txt”, “w”)
# do stuff to the file
file.close()
86. file = open(“filename.txt”, “r”)
print(cont)
file.close()
87. file = open(“filename.txt”, “r”)
print(“Finished”)
file.close()
88. file = open(“filename.txt”, “r”)
file.close()
89. file = open(“newfile.txt”, “w”)
file.write(“This has been written to a file”)
file.close()file = open(“newfile.txt”, “r”)
file.close()
90. msg = “Hello world!”
file = open(“newfile.txt”, “w”)
amount_written = file.write(msg)
print(amount_written)
file.close()
91. try:
f = open(“filename.txt”)
finally:
f.close()
92. with open(“filename.txt”) as f:
93. some_func():
print(“Hi!”)var = some_func()
print(var)
94. ages = {“Dave”: 24, “Mary”: 42, “John”: 58}
print(ages[“Dave”])
print(ages[“Mary”])
95. primary = {
“red”: [255, 0, 0],
“green”: [0, 255, 0],
“blue”: [0, 0, 255],
}print(primary[“red”])
print(primary[“yellow”])
[1, 2, 3]: “one two three”,
}
97. nums = {
1: “one”,
2: “two”,
3: “three”,
}
print(1 in nums)
print(“three” in nums)
print(4 not in nums)
98. pairs = {1: “apple”,
“orange”: [2, 3, 4],
True: False,
: “True”,
}print(pairs.get(“orange”))
print(pairs.get(7))
print(pairs.get(12345, “not in “))
99. words = (“spam”, “eggs”, “sausages”,)
100. my_tuple = “one”, “two”, “three”
print(my_tuple)
101. squares = [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
print(squares[2:6])
print(squares[3:8])
print(squares[0:1])
102. squares = [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
print(squares[:7])
print(squares[7:])
103. squares = [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
print(squares[::2])
print(squares[2:8:3])
104. squares = [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
print(squares[1:-1])
105. cubes = [i**3 for i in range(5)]print(cubes)
106. evens=[i**2 for i in range(10) if i**2 % 2 == 0]print(evens)
107. even = [2*i for i in range(10**100)]
108. nums = [4, 5, 6]
msg = “Numbers: {0} {1} {2}”. format(nums, nums, nums)
print(msg)
109. a = “{x}, {y}”.format(x=5, y=12)
print(a)
110. print(“, “.join([“spam”, “eggs”, “ham”]))
#prints “spam, eggs, ham”print(“Hello ME”.replace(“ME”, “world”))
#prints “Hello world”

print(“This is a sentence.”.startswith(“This”))
# prints “True”

print(“This is a sentence.”.endswith(“sentence.”))
# prints “True”

print(“This is a sentence.”.upper())
# prints “THIS IS A SENTENCE.”

print(“AN ALL CAPS SENTENCE”.lower())
#prints “an all caps sentence”

print(“spam, eggs, ham”.split(“, “))
#prints “[‘spam’, ‘eggs’, ‘ham’]”

111. print(min(1, 2, 3, 4, 0, 2, 1))
print(max([1, 4, 9, 2, 5, 6, 8]))
print(abs(-99))
print(abs(42))
print(sum([1, 2, 3, 4, 5]))
112. nums = [55, 44, 33, 22, 11]if all([i > 5 for i in nums]):
print(“All larger than 5”)

if any([i % 2 == 0 for i in nums]):
print(“At least one is even”)

for v in enumerate(nums):
print(v)

113. for char in “abcdefghijklmnopqrstuvwxyz”:
perc = 100 * count_char(text, char) / len(text)
print(“{0} – {1}%”.format(char, round(perc, 2)))

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