Python : chaînes et listes

word = "Python"
print(word[0])
print(word[5])
print(len(word))
print(word[len(word) - 1])
print(word[-2])

P
n
6
n
o

s = "hello world"
print(s[0:5])
print(s[6:])
print("wor" in s)
print(s.upper())
print(s.count("o"))
print(s)

hello
world
True
HELLO WORLD
2
hello world

def count_vowels(s):
    count = 0
    for ch in s:
        if ch in "aeiou":
            count = count + 1
    return count

>>> count_vowels("banana")
>>> count_vowels("sky")
>>> count_vowels("Ada Lovelace")

>>> count_vowels("banana")
3
>>> count_vowels("sky")
0
>>> count_vowels("Ada Lovelace")
5

def reverse(s):
    result = ""
    for ch in s:
        result = ch + result
    return result

def is_palindrome(s):
    return s == reverse(s)

>>> reverse("abc")
>>> is_palindrome("kayak")
>>> is_palindrome("Kayak")

>>> reverse("abc")
'cba'
>>> is_palindrome("kayak")
True
>>> is_palindrome("Kayak")
False

def shift_letter(c, k):
    position = ord(c) - ord("a")
    new_position = (position + k) % 26
    return chr(ord("a") + new_position)

def caesar(s, k):
    result = ""
    for ch in s:
        result = result + shift_letter(ch, k)
    return result

>>> shift_letter("a", 3)
>>> shift_letter("z", 1)
>>> caesar("hello", 3)
>>> caesar("khoor", 23)

>>> shift_letter("a", 3)
'd'
>>> shift_letter("z", 1)
'a'
>>> caesar("hello", 3)
'khoor'
>>> caesar("khoor", 23)
'hello'

items = []
items.append("bread")
items.append("milk")
items.append("eggs")
print(len(items))
print(items)
print(items[1])
for item in items:
    print("-", item)
print("milk" in items)

3
['bread', 'milk', 'eggs']
milk
- bread
- milk
- eggs
True

grades = [12, 15, 9, 14]
total = 0
for g in grades:
    total = total + g
print(total / len(grades))
print(sum(grades) / len(grades))
print(max(grades), min(grades))
print(sorted(grades))
print(grades)

12.5
12.5
15 9
[9, 12, 14, 15]
[12, 15, 9, 14]

def position_of_largest(lst):
    best = 0
    for i in range(1, len(lst)):
        if lst[i] > lst[best]:
            best = i
    return best

def evens(lst):
    result = []
    for x in lst:
        if x % 2 == 0:
            result.append(x)
    return result

>>> position_of_largest([4, 9, 2, 9])
>>> position_of_largest([7])
>>> evens([3, 8, 5, 2, 6])
>>> evens([1, 3])

>>> position_of_largest([4, 9, 2, 9])
1
>>> position_of_largest([7])
0
>>> evens([3, 8, 5, 2, 6])
[8, 2, 6]
>>> evens([1, 3])
[]

a = [1, 2]
b = a
b.append(3)
print(a)
c = a[:]
c.append(4)
print(a)
print(c)

[1, 2, 3]
[1, 2, 3]
[1, 2, 3, 4]

def find(lst, v):
    for i in range(len(lst)):
        if lst[i] == v:
            return i
    return -1

def has_duplicate(lst):
    for i in range(len(lst)):
        for j in range(i + 1, len(lst)):
            if lst[i] == lst[j]:
                return True
    return False

>>> find([5, 3, 8, 3], 3)
>>> find([5, 3, 8, 3], 7)
>>> find([], 1)
>>> has_duplicate([4, 1, 7, 1])
>>> has_duplicate([4, 1, 7])

>>> find([5, 3, 8, 3], 3)
1
>>> find([5, 3, 8, 3], 7)
-1
>>> find([], 1)
-1
>>> has_duplicate([4, 1, 7, 1])
True
>>> has_duplicate([4, 1, 7])
False

names = ["Ada", "Leo", "Zoe"]
scores = [15, 12, 17]
best = 0
for i in range(1, len(names)):
    if scores[i] > scores[best]:
        best = i
print(names[best], scores[best])
for i in range(len(names)):
    if scores[i] >= 15:
        print(names[i])

Zoe 17
Ada
Zoe

text = "les lettres les plus frequentes"
counts = [0] * 26
total = 0
for c in text:
    if c in "abcdefghijklmnopqrstuvwxyz":
        position = ord(c) - ord("a")
        counts[position] = counts[position] + 1
        total = total + 1
best = 0
for i in range(26):
    if counts[i] > counts[best]:
        best = i
print(chr(best + ord("a")), counts[best], total)

e 7 27

grid = [["X", "O", "X"], [" ", "X", "O"], ["O", " ", "X"]]
for row in grid:
    print(row[0] + "|" + row[1] + "|" + row[2])
count = 0
for r in range(3):
    for c in range(3):
        if grid[r][c] == "X":
            count = count + 1
print("X:", count)
print(grid[1][2])

X|O|X
 |X|O
O| |X
X: 4
O

def longest_word(sentence):
    words = sentence.split()
    best = words[0]
    for w in words:
        if len(w) > len(best):
            best = w
    return best

def word_count(sentence):
    return len(sentence.split())

>>> "a red fox".split()
>>> longest_word("the quick brown fox")
>>> word_count("the quick brown fox")
>>> "-".join(["a", "b", "c"])

>>> "a red fox".split()
['a', 'red', 'fox']
>>> longest_word("the quick brown fox")
'quick'
>>> word_count("the quick brown fox")
4
>>> "-".join(["a", "b", "c"])
'a-b-c'

u = [3 * n + 2 for n in range(5)]
print(u)

def f(x):
    return x * x - 4

xs = [-3, -1, 0, 2, 5]
ys = [f(x) for x in xs]
print(ys)
print([y for y in ys if y > 0])
print([n for n in range(1, 31) if n % 7 == 0])

[2, 5, 8, 11, 14]
[5, -3, -4, 0, 21]
[5, 21]
[7, 14, 21, 28]

ys = []
for x in xs:
    ys.append(f(x))

import random

def masked(word, letters):
    result = ""
    for ch in word:
        if ch in letters:
            result = result + ch
        else:
            result = result + "-"
    return result

def is_won(word, letters):
    return masked(word, letters) == word

words = ["python", "loop", "list"]
secret = words[random.randint(0, len(words) - 1)]
letters = []
errors = 0
while errors < 6 and not is_won(secret, letters):
    print(masked(secret, letters))
    guess = input("Letter? ")
    letters.append(guess)
    if guess not in secret:
        errors = errors + 1
        print("Wrong! Errors:", errors)
if is_won(secret, letters):
    print("You won:", secret)
else:
    print("You lost! The word was", secret)

----
Letter? o
-oo-
Letter? l
loo-
Letter? x
Wrong! Errors: 1
loo-
Letter? p
You won: loop