11.3. Function Parameters¶
Parameter - Receiving variable used within the function
Required parameter - necessary to call that function
Required parameter - specified at leftmost side
Default parameter - optional to call that function
Default parameter - Has default value
Default parameter - Could be overridden
Default parameter - Specified at rightmost side
- parameter¶
Receiving variable used within the function/block
- required parameter¶
Parameter which is necessary to call function
- default parameter¶
Parameter which is optional and has default value (if not specified at call time)
- signature¶
Function name and its parameters
11.3.1. Syntax¶
Function definition with parameters:
def myfunction(<parameters>):
<do something>
>>> def add(a, b):
... return a + b
You can also write this way, but this is not to be advised.
>>> def add(a, b): ...
11.3.2. Required Parameters¶
Parameters without default values are required
>>> def add(a, b):
... return a + b
>>>
>>>
>>> add()
Traceback (most recent call last):
TypeError: add() missing 2 required positional arguments: 'a' and 'b'
>>>
>>> add(1)
Traceback (most recent call last):
TypeError: add() missing 1 required positional argument: 'b'
>>>
>>> add(1, 2)
3
>>>
>>> add(1, 2, 3)
Traceback (most recent call last):
TypeError: add() takes 2 positional arguments but 3 were given
11.3.3. Default Parameters¶
Default parameters has default value
Function will use default value if not overwritten by user
Parameters with default values can be omitted while executing
>>> def add(a=10, b=20):
... return a + b
>>>
>>>
>>> add()
30
>>>
>>> add(1)
21
>>>
>>> add(1, 2)
3
>>>
>>> add(1, 2, 3)
Traceback (most recent call last):
TypeError: add() takes from 0 to 2 positional arguments but 3 were given
11.3.4. Required and Default Parameters¶
Required parameters must be at the left side
Default parameters must be at the right side
There cannot be required parameter after optional
>>> def add(a, b=20):
... return a + b
>>>
>>>
>>> add()
Traceback (most recent call last):
TypeError: add() missing 1 required positional argument: 'a'
>>>
>>> add(1)
21
>>>
>>> add(1, 2)
3
>>>
>>> add(1, 2, 3)
Traceback (most recent call last):
TypeError: add() takes from 1 to 2 positional arguments but 3 were given
11.3.5. Errors¶
>>> def add(a=1, b):
... return a + b
Traceback (most recent call last):
SyntaxError: non-default argument follows default argument
>>> def add(a, b=1, c):
... return a + b + c
Traceback (most recent call last):
SyntaxError: non-default argument follows default argument
>>> def add(a, b=1, c, d, e, f=8, g=9):
... return a + b
Traceback (most recent call last):
SyntaxError: non-default argument follows default argument
>>> def add(a, c, d, e, b=1, f=8, g=9):
... return a + b
11.3.6. Signature¶
>>> from inspect import signature
>>>
>>>
>>> def add(a, b=2):
... return a + b
>>>
>>>
>>> signature(add)
<Signature (a, b=2)>
11.3.7. Use Case - 0x01¶
>>> def echo(text):
... return text
11.3.8. Use Case - 0x03¶
>>> def login(username, password): ...
11.3.9. Use Case - 0x02¶
>>> def connect(username, password, host='127.0.0.1', port=22,
... ssl=True, keep_alive=1, persistent=False): ...
11.3.10. Use Case - 0x03¶
Definition of pandas.read_csv() function:
>>> def read_csv(filepath_or_buffer, sep=', ', delimiter=None, header='infer',
... names=None, index_col=None, usecols=None, squeeze=False,
... prefix=None, mangle_dupe_cols=True, dtype=None, engine=None,
... converters=None, true_values=None, false_values=None,
... skipinitialspace=False, skiprows=None, nrows=None,
... na_values=None, keep_default_na=True, na_filter=True,
... verbose=False, skip_blank_lines=True, parse_dates=False,
... infer_datetime_format=False, keep_date_col=False,
... date_parser=None, dayfirst=False, iterator=False,
... chunksize=None, compression='infer', thousands=None,
... decimal=b'.', lineterminator=None, quotechar='"',
... quoting=0, escapechar=None, comment=None, encoding=None,
... dialect=None, tupleize_cols=None, error_bad_lines=True,
... warn_bad_lines=True, skipfooter=0, doublequote=True,
... delim_whitespace=False, low_memory=True, memory_map=False,
... float_precision=None): ...
11.3.11. Assignments¶
"""
* Assignment: Function Parameters Square
* Type: class assignment
* Complexity: easy
* Lines of code: 2 lines
* Time: 2 min
English:
1. Define function `square`:
a. takes `x: int`
b. returns square of `x`
2. Run doctests - all must succeed
Polish:
1. Zdefiniuj funkcję `square`:
a. przyjmuje `x: int`
b. zwraca kwadrat `x`
2. Uruchom doctesty - wszystkie muszą się powieść
Tests:
>>> import sys; sys.tracebacklimit = 0
>>> from inspect import isfunction
>>> assert square is not Ellipsis, \
'Write solution inside `square` function'
>>> assert isfunction(square), \
'Object `square` must be a function'
>>> square(2)
4
>>> square(8)
64
>>> square(32)
1024
"""
# Returns square of `x`
# type: Callable[[int], int]
...
"""
* Assignment: Function Parameters IsEven
* Type: class assignment
* Complexity: easy
* Lines of code: 2 lines
* Time: 2 min
English:
1. Define function `is_even`:
a. takes `x: int`
b. returns True/False if `x` is even
2. Run doctests - all must succeed
Polish:
1. Zdefiniuj funkcję `is_even`:
a. przyjmuje `x: int`
b. zwraca True/False czy `x` jest parzysty
2. Uruchom doctesty - wszystkie muszą się powieść
Tests:
>>> import sys; sys.tracebacklimit = 0
>>> from inspect import isfunction
>>> assert is_even is not Ellipsis, \
'Write solution inside `is_even` function'
>>> assert isfunction(is_even), \
'Object `is_even` must be a function'
>>> is_even(2)
True
>>> is_even(3)
False
>>> is_even(4)
True
>>> is_even(5)
False
>>> is_even(6)
True
>>> is_even(7)
False
"""
# Returns True/False if `x` is even
# type: Callable[[int], bool]
...
"""
* Assignment: Function Parameters Sum
* Type: class assignment
* Complexity: easy
* Lines of code: 2 lines
* Time: 2 min
English:
1. Define function `total`:
a. takes `data: tuple|list|set` of objects `int | float`
b. returns sum of all values in a sequence
2. Run doctests - all must succeed
Polish:
1. Zdefiniuj funkcję `total`:
a. przyjmuje `data: tuple|list|set` obiektów `int | float`
b. zwraca sumę wszystkich wartości z sekwencji
2. Uruchom doctesty - wszystkie muszą się powieść
Hints:
* `sum()`
Tests:
>>> import sys; sys.tracebacklimit = 0
>>> from inspect import isfunction
>>> assert total is not Ellipsis, \
'Write solution inside `total` function'
>>> assert isfunction(total), \
'Object `total` must be a function'
>>> total([1,2,3])
6
>>> total([1,2,3,4,5,6])
21
>>> total(range(0,101))
5050
"""
# Returns sum of all values in a sequence
# type: Callable[[tuple|list|set], int]
...
"""
* Assignment: Function Parameters Echo
* Type: class assignment
* Complexity: easy
* Lines of code: 2 lines
* Time: 3 min
English:
1. Define function `echo` with two parameters
2. Parameter `a` is required
3. Parameter `b` is required
4. Return `a` and `b` as a `tuple`
5. Run doctests - all must succeed
Polish:
1. Zdefiniuj funkcję `echo` z dwoma parametrami
2. Parametr `a` jest wymagany
3. Parametr `b` jest wymagany
4. zwróć `a` i `b` jako `tuple`
5. Uruchom doctesty - wszystkie muszą się powieść
Tests:
>>> import sys; sys.tracebacklimit = 0
>>> from inspect import isfunction
>>> assert echo is not Ellipsis, \
'Write solution inside `echo` function'
>>> assert isfunction(echo), \
'Object `echo` must be a function'
>>> echo(1, 2)
(1, 2)
>>> echo(3, 4)
(3, 4)
"""
"""
* Assignment: Function Parameters Default
* Type: class assignment
* Complexity: easy
* Lines of code: 4 lines
* Time: 3 min
English:
1. Define function `default` with two parameters
2. Parameter `a` is required
3. Parameter `b` is optional and has default value `None`
4. If only one argument was passed, consider second equal to the first one
5. Return `a` and `b` as a `dict`, i.e. {'a': 1, 'b': 1}
6. Run doctests - all must succeed
Polish:
1. Zdefiniuj funkcję `default` z dwoma parametrami
2. Parametr `a` jest wymagany
3. Parametr `b` jest opcjonalny i ma domyślną wartość `None`
4. Jeżeli tylko jeden argument był podany, przyjmij drugi równy pierwszemu
5. Zwróć `a` i `b` jako `dict`, np. {'a': 1, 'b': 1}
6. Uruchom doctesty - wszystkie muszą się powieść
Tests:
>>> import sys; sys.tracebacklimit = 0
>>> from inspect import isfunction
>>> assert default is not Ellipsis, \
'Write solution inside `default` function'
>>> assert isfunction(default), \
'Object `default` must be a function'
>>> default(1)
{'a': 1, 'b': 1}
>>> default(2, 3)
{'a': 2, 'b': 3}
"""
"""
* Assignment: Function Parameters BloodPressure
* Type: class assignment
* Complexity: medium
* Lines of code: 10 lines
* Time: 13 min
English:
1. Table contains Blood Pressure classification according to American Heart Association [1]
2. User inputs blood pressure in `XXX/YY` or `XXX/YYY` format
3. User will not try to input invalid data
4. Data format:
a. `XXX: int` systolic pressure
b. `YY: int` or `YYY: int` diastolic pressure
5. Print status of given blood pressure
6. If systolic and diastolic values are in different categories, assume worst case
7. Run doctests - all must succeed
Polish:
1. Tabela zawiera klasyfikację ciśnienia krwi wg American Heart Association [1]
2. Użytkownik wprowadza ciśnienie krwi w formacie `XXX/YY` lub `XXX/YYY`
3. Użytkownik nie będzie próbował wprowadzać danych niepoprawnych
4. Format danych:
a. `XXX: int` to wartość ciśnienia skurczowego (ang. systolic)
b. `YY: int` lub `YYY: int` to wartość ciśnienia rozkurczowego (ang. diastolic)
5. Wypisz status wprowadzonego ciśnienia krwi
6. Gdy wartości ciśnienia skurczowego i rozkurczowego należą do różnych kategorii, przyjmij gorszy przypadek
7. Uruchom doctesty - wszystkie muszą się powieść
Hints:
* `and`
* `or`
References:
[1] Whelton, Paul K. and et al.
2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the
Prevention, Detection, Evaluation, and Management of High Blood Pressure
in Adults: Executive Summary: A Report of the American College of
Cardiology/American Heart Association Task Force on Clinical Practice Guidelines.
Journal of Hypertension. vol 71. pages 1269–1324. 2018. doi: 10.1161/HYP.0000000000000066
Tests:
TODO: Better Tests
>>> import sys; sys.tracebacklimit = 0
>>> result = blood_pressure(0,0)
>>> assert result is not Ellipsis, \
'Assign your result to variable `result`'
>>> assert type(result) is str, \
'Variable `result` has invalid type, should be str'
>>> result in (STATUS_NORMAL, STATUS_ELEVATED, STATUS_HYPERTENSION_STAGE_1,
... STATUS_HYPERTENSION_STAGE_2, STATUS_HYPERTENSIVE_CRISIS)
True
>>> blood_pressure(115, 75)
'Normal'
>>> blood_pressure(125, 75)
'Elevated'
>>> blood_pressure(135, 85)
'Hypertension stage 1'
>>> blood_pressure(145, 95)
'Hypertension stage 2'
>>> blood_pressure(195, 135)
'Hypertensive Crisis'
>>> blood_pressure(119, 0)
'Normal'
>>> blood_pressure(120, 0)
'Elevated'
>>> blood_pressure(0, 79)
'Normal'
>>> blood_pressure(0, 80)
'Hypertension stage 1'
>>> blood_pressure(120, 80)
'Hypertension stage 1'
>>> blood_pressure(129, 0)
'Elevated'
>>> blood_pressure(130, 0)
'Hypertension stage 1'
>>> blood_pressure(0, 79)
'Normal'
>>> blood_pressure(0, 80)
'Hypertension stage 1'
>>> blood_pressure(130, 80)
'Hypertension stage 1'
>>> blood_pressure(139, 0)
'Hypertension stage 1'
>>> blood_pressure(140, 0)
'Hypertension stage 2'
>>> blood_pressure(0, 89)
'Hypertension stage 1'
>>> blood_pressure(0, 90)
'Hypertension stage 2'
>>> blood_pressure(140, 90)
'Hypertension stage 2'
>>> blood_pressure(180, 0)
'Hypertension stage 2'
>>> blood_pressure(181, 0)
'Hypertensive Crisis'
>>> blood_pressure(0, 120)
'Hypertension stage 2'
>>> blood_pressure(0, 121)
'Hypertensive Crisis'
>>> blood_pressure(181, 121)
'Hypertensive Crisis'
"""
STATUS_NORMAL = 'Normal'
STATUS_ELEVATED = 'Elevated'
STATUS_HYPERTENSION_STAGE_1 = 'Hypertension stage 1'
STATUS_HYPERTENSION_STAGE_2 = 'Hypertension stage 2'
STATUS_HYPERTENSIVE_CRISIS = 'Hypertensive Crisis'
# | 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 |
# One of the STATUS_*
# type: Callable[[int,int], str]
def blood_pressure(systolic, diastolic):
return ...