5.4. Conditional Expressions¶

5.4.1. Conjunction¶

Listing 5.38. Inside joke (see José Jiménez)¶

firstname = 'Mark'
lastname = 'Watney'

if firstname == 'Mark' and lastname == 'Watney':
    print('Hello Space Pirate')
else:
    print('Sorry, astronauts only')
# Hello Space Pirate

5.4.2. Disjunction¶

name = 'Watney'

if name == 'Watney' or name == 'Twardowski':
    print('Hello astronaut')
else:
    print('Sorry, astronauts only')
# Hello astronaut

5.4.3. Boolean Algebra¶

Use parenthesis for explicit order

firstname = 'José'
lastname = 'Jiménez'

if (firstname == 'Mark' and lastname == 'Watney') \
        or (firstname == 'Jan' and lastname == 'Twardowski') \
        or (firstname == 'Melissa' and lastname == 'Lewis'):

    print('Hello astronaut')
else:
    print('Sorry, astronauts only')

# Sorry, astronauts only

Listing 5.39. Complex conditions¶

for line in file:
    if line and (not line.startswith('#') or not line.isspace()):
        ...


for line in file:
    if len(line) == 0:
        continue

    if line.startswith('#'):
        continue

    if line.isspace():
        continue

    ...

5.4.4. Contains¶

text = 'Monty Python'

if 'Python' in text:
    print('Yes')
else:
    print('No')
# Yes

crew = ['Lewis', 'Watney', 'Twardowski']

if 'Jiménez' in crew:
    print('Yes')
else:
    print('No')
# No

crew = {'Lewis', 'Watney', 'Twardowski'}

if 'Jiménez' in crew:
    print('Yes')
else:
    print('No')
# No

5.4.5. Identity¶

name = None

if name is None:
    print('Name is empty')

5.4.6. Negation¶

not negates (logically inverts) condition

name = None

if not name:
    print('Name is empty')

crew = {'Lewis', 'Watney', 'Twardowski'}

if 'Ivanovich' not in crew:
    print('You are not assigned to the crew')
# You are not assigned to the crew

name = None

if name is not None:
    print(name)

5.4.7. Assignments¶

5.4.7.1. Conditional Expression¶

Assignment name: Conditional Expression
Last update: 2020-10-01
Complexity level: medium
Lines of code to write: 25 lines
Estimated time of completion: 21 min
Solution: solution/conditional_expression.py

English

Use data from "Input" section (see below)
Table contains Blood Pressure classification according to American Heart Association [Weal18]
User inputs blood pressure in XXX/YY or XXX/YYY format
User will not try to input invalid data
Data format:
- XXX: int systolic pressure
- YY: int or YYY: int diastolic pressure
Print status of given blood pressure
If systolic and diastolic values are in different categories, assume worst case

Polish

Użyj danych z sekcji "Input" (patrz poniżej)
Tabela zawiera klasyfikację ciśnienia krwi wg American Heart Association [Weal18]
Użytkownik wprowadza ciśnienie krwi w formacie XXX/YY lub XXX/YYY
Użytkownik nie będzie próbował wprowadzać danych niepoprawnych
Format danych:
- XXX: int to wartość ciśnienia skurczowego (ang. systolic)
- YY: int lub YYY: int to wartość ciśnienia rozkurczowego (ang. diastolic)
Wypisz status wprowadzonego ciśnienia krwi
Gdy wartości ciśnienia skurczowego i rozkurczowego należą do różnych kategorii, przyjmij gorszy przypadek

Table 5.2. Classification of blood pressure in adults [Weal18]¶
Blood Pressure Category	Systolic [mm Hg]	Operator	Diastolic [mm Hg]
Normal	Less than 120	and	Less than 80
Elevated	120-129	and	Less than 80
Hypertension stage 1	130-139	or	80-89
Hypertension stage 2	140 or higher	or	90 or higher
Hypertensive Crisis	Higher than 180	and/or	Higher than 120

Input

'119/79': 'Normal',
'120/80': 'Hypertension stage 1',
'121/79': 'Elevated',
'120/81': 'Hypertension stage 1',
'130/80': 'Hypertension stage 1',
'130/89': 'Hypertension stage 1',
'140/85': 'Hypertension stage 2',
'140/89': 'Hypertension stage 2',
'141/90': 'Hypertension stage 2',
'141/91': 'Hypertension stage 2',
'180/120': ('Hypertension stage 2', 'Hypertensive Crisis')

The whys and wherefores

Reading user input
Type casting
Conditional statements
Composite conditional statements
Checking for corner cases
Defining constants and variables