ch03

Author: adii1823

ch03/any.py

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+items = [0, None, 0.0, True, 0, 7]  # True and 7 evaluate to True
+
+found = False  # this is called "flag"
+for item in items:
+    print('scanning item', item)
+    if item:
+        found = True  # we update the flag
+        break
+
+if found:  # we inspect the flag
+    print('At least one item evaluates to True')
+else:
+    print('All items evaluate to False')

ch03/binary.2.py

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+n = 39
+remainders = []
+while n > 0:
+    n, remainder = divmod(n, 2)
+    remainders.append(remainder)
+
+remainders.reverse()
+print(remainders)

ch03/binary.py

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+"""
+6 / 2 = 3 (remainder: 0)
+3 / 2 = 1 (remainder: 1)
+1 / 2 = 0 (remainder: 1)
+List of remainders: 0, 1, 1.
+Reversed is 1, 1, 0, which is also the binary repres. of 6: 110
+"""
+
+n = 39
+remainders = []
+while n > 0:
+    remainder = n % 2  # remainder of division by 2
+    remainders.append(remainder)  # we keep track of remainders
+    n //= 2  # we divide n by 2
+
+remainders.reverse()
+print(remainders)

ch03/compress.py

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+from itertools import compress
+data = range(10)
+even_selector = [1, 0] * 10
+odd_selector = [0, 1] * 10
+
+even_numbers = list(compress(data, even_selector))
+odd_numbers = list(compress(data, odd_selector))
+
+print(odd_selector)
+print(list(data))
+print(even_numbers)
+print(odd_numbers)

ch03/conditional.1.py

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+late = True
+if late:
+    print('I need to call my manager!')

ch03/conditional.2.py

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+late = False
+if late:
+    print('I need to call my manager!')  #1
+else:
+    print('no need to call my manager...')  #2

ch03/coupons.dict.py

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+customers = [
+    dict(id=1, total=200, coupon_code='F20'),  # F20: fixed, £20
+    dict(id=2, total=150, coupon_code='P30'),  # P30: percent, 30%
+    dict(id=3, total=100, coupon_code='P50'),  # P50: percent, 50%
+    dict(id=4, total=110, coupon_code='F15'),  # F15: fixed, £15
+]
+discounts = {
+    'F20': (0.0, 20.0),  # each value is (percent, fixed)
+    'P30': (0.3, 0.0),
+    'P50': (0.5, 0.0),
+    'F15': (0.0, 15.0),
+}
+for customer in customers:
+    code = customer['coupon_code']
+    percent, fixed = discounts.get(code, (0.0, 0.0))
+    customer['discount'] = percent * customer['total'] + fixed
+
+for customer in customers:
+    print(customer['id'], customer['total'], customer['discount'])

ch03/coupons.py

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+customers = [
+    dict(id=1, total=200, coupon_code='F20'),  # F20: fixed, £20
+    dict(id=2, total=150, coupon_code='P30'),  # P30: percent, 30%
+    dict(id=3, total=100, coupon_code='P50'),  # P50: percent, 50%
+    dict(id=4, total=110, coupon_code='F15'),  # F15: fixed, £15
+]
+for customer in customers:
+    code = customer['coupon_code']
+    if code == 'F20':
+        customer['discount'] = 20.0
+    elif code == 'F15':
+        customer['discount'] = 15.0
+    elif code == 'P30':
+        customer['discount'] = customer['total'] * 0.3
+    elif code == 'P50':
+        customer['discount'] = customer['total'] * 0.5
+    else:
+        customer['discount'] = 0.0
+
+for customer in customers:
+    print(customer['id'], customer['total'], customer['discount'])

ch03/discount.py

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+from datetime import date, timedelta
+
+today = date.today()
+tomorrow = today + timedelta(days=1)  # today + 1 day is tomorrow
+products = [
+    {'sku': '1', 'expiration_date': today, 'price': 100.0},
+    {'sku': '2', 'expiration_date': tomorrow, 'price': 50},
+    {'sku': '3', 'expiration_date': today, 'price': 20},
+]
+
+for product in products:
+    if product['expiration_date'] != today:
+        continue
+    product['price'] *= 0.8  # equivalent to applying 20% discount
+    print(
+        'Price for sku', product['sku'],
+        'is now', product['price'])

ch03/errorsalert.py

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+# The send_email function is defined here to enable you to play with
+# code, but of course it doesn't send an actual email.
+def send_email(*a):
+    print (*a)
+
+alert_system = 'console'  # other value can be 'email'
+error_severity = 'critical'  # other values: 'medium' or 'low'
+error_message = 'OMG! Something terrible happened!'
+
+if alert_system == 'console':
+    print(error_message)  #1
+elif alert_system == 'email':
+    if error_severity == 'critical':
+        send_email('[email protected]', error_message)  #2
+    elif error_severity == 'medium':
+        send_email('[email protected]', error_message)  #3
+    else:
+        send_email('[email protected]', error_message)  #4