11.3. Loop For Unpacking¶
11.3.1. Recap¶
>>> a, b = 1, 2
>>> a, b = (1, 2)
>>> k, v = (1, 2)
>>> key, value = (1, 2)
>>> role, name = ('commander', 'Melissa Lewis')
11.3.2. List of Pairs¶
>>> DATA = [
... ('commander', 'Melissa Lewis'),
... ('botanist', 'Mark Watney'),
... ('chemist', 'Alex Vogel'),
... ]
>>>
>>> for role, name in DATA:
... print(f'{role} -> {name}')
commander -> Melissa Lewis
botanist -> Mark Watney
chemist -> Alex Vogel
11.3.3. List of Tuples¶
>>> DATA = [
... (5.1, 3.5, 1.4, 0.2, 'setosa'),
... (5.7, 2.8, 4.1, 1.3, 'versicolor'),
... (6.3, 2.9, 5.6, 1.8, 'virginica'),
... ]
>>>
>>> for sepal_length, sepal_width, petal_length, petal_width, species in DATA:
... print(f'{species} -> {sepal_length}')
setosa -> 5.1
versicolor -> 5.7
virginica -> 6.3
>>> DATA = [
... (5.1, 3.5, 1.4, 0.2, 'setosa'),
... (5.7, 2.8, 4.1, 1.3, 'versicolor'),
... (6.3, 2.9, 5.6, 1.8, 'virginica'),
... ]
>>>
>>> for sl, sw, pl, pw, s in DATA:
... print(f'{s} -> {sl}')
setosa -> 5.1
versicolor -> 5.7
virginica -> 6.3
11.3.4. Unused Values¶
>>> DATA = [
... (5.1, 3.5, 1.4, 0.2, 'setosa'),
... (5.7, 2.8, 4.1, 1.3, 'versicolor'),
... (6.3, 2.9, 5.6, 1.8, 'virginica'),
... ]
>>>
>>> for sepal_length, _, _, _, species in DATA:
... print(f'{species} -> {sepal_length}')
setosa -> 5.1
versicolor -> 5.7
virginica -> 6.3
>>> DATA = [
... (5.8, 2.7, 5.1, 1.9, 'virginica'),
... (5.1, 3.5, 1.4, 0.2, 'setosa'),
... (5.7, 2.8, 4.1, 1.3, 'versicolor'),
... ]
>>>
>>> for sepal_length, *_, species in DATA:
... print(f'{species} -> {sepal_length}')
virginica -> 5.8
setosa -> 5.1
versicolor -> 5.7
11.3.5. Mixed¶
>>> DATA = [
... (1, 2),
... ('name', 'Mark Watney'),
... ('agency', ['NASA', 'ESA', 'POLSA']),
... ((1, 2), ['botanist', 'commander', 'pilot']),
... (['Ares1', 'Are2', 'Ares3'], 1),
... ]
>>>
>>> for first, second in DATA:
... print(f'{first} -> {second}')
1 -> 2
name -> Mark Watney
agency -> ['NASA', 'ESA', 'POLSA']
(1, 2) -> ['botanist', 'commander', 'pilot']
['Ares1', 'Are2', 'Ares3'] -> 1
11.3.6. Assignments¶
"""
* Assignment: Loop Unpacking Months
* Type: class assignment
* Complexity: easy
* Lines of code: 2 lines
* Time: 5 min
English:
1. Use `enumerate()` to convert `MONTH` into `result: dict[int,str]`:
a. Keys: month number
b. Values: month name
2. Use unpacking in the loop
3. Run doctests - all must succeed
Polish:
1. Użyj `enumerate()` do konwersji `MONTH` w `result: dict[int,str]`:
a. klucz: numer miesiąca
b. wartość: nazwa miesiąca
2. Użyj rozpakowywania w pętli
3. Uruchom doctesty - wszystkie muszą się powieść
Tests:
>>> import sys; sys.tracebacklimit = 0
>>> from pprint import pprint
>>> assert result is not Ellipsis, \
'Assign your result to variable `result`'
>>> assert type(result) is dict, \
'Variable `result` has invalid type, should be dict'
>>> assert all(type(x) is int for x in result.keys())
>>> assert all(type(x) is str for x in result.values())
>>> assert all(x in result.keys() for x in range(1, 13))
>>> assert all(x in result.values() for x in MONTHS)
>>> 13 not in result
True
>>> 0 not in result
True
>>> pprint(result)
{1: 'January',
2: 'February',
3: 'March',
4: 'April',
5: 'May',
6: 'June',
7: 'July',
8: 'August',
9: 'September',
10: 'October',
11: 'November',
12: 'December'}
"""
MONTHS = ['January', 'February', 'March', 'April',
'May', 'June', 'July', 'August', 'September',
'October', 'November', 'December']
# Dict with month number and name. Start with 1
# type: dict[int,str]
result = ...
"""
* Assignment: Loop Unpacking Endswith
* Type: class assignment
* Complexity: medium
* Lines of code: 4 lines
* Time: 8 min
English:
1. Define `result: set[str]`
2. Iterating over `DATA` unpack row to:
a. `sl,sw,pl,pw` - all beside last
b. `species` - last in the row
3. Append to `result` species names with suffix in `SUFFIXES`
4. Run doctests - all must succeed
Polish:
1. Zdefiniuj `result: set[str]`
2. Iterując po `DATA` rozpakuj wiersz do:
a. `sl,sw,pl,pw` - wszystkie poza ostatnim
b. `species` - ostatni w wierszu
3. Dodaj do `result` nazwy gatunków (species) z końcówką w `SUFFIXES`
4. Uruchom doctesty - wszystkie muszą się powieść
Hints:
* `str.endswith()`
Tests:
>>> import sys; sys.tracebacklimit = 0
>>> assert result is not Ellipsis, \
'Assign your result to variable `result`'
>>> assert type(result) is set, \
'Result must be a set'
>>> assert len(result) > 0, \
'Result cannot be empty'
>>> assert all(type(element) is str for element in result), \
'All elements in result must be a str'
>>> 'virginica' in result
True
>>> 'setosa' in result
True
>>> 'versicolor' in result
False
"""
DATA = [
('sepal_length', 'sepal_width', 'petal_length', 'petal_width', 'species'),
(5.8, 2.7, 5.1, 1.9, 'virginica'),
(5.1, 3.5, 1.4, 0.2, 'setosa'),
(5.7, 2.8, 4.1, 1.3, 'versicolor'),
(6.3, 2.9, 5.6, 1.8, 'virginica'),
(6.4, 3.2, 4.5, 1.5, 'versicolor'),
(4.7, 3.2, 1.3, 0.2, 'setosa'),
(7.0, 3.2, 4.7, 1.4, 'versicolor'),
(7.6, 3.0, 6.6, 2.1, 'virginica'),
(4.6, 3.1, 1.5, 0.2, 'setosa'),
]
SUFFIXES = ('ca', 'osa')
# species names with suffix in `SUFFIXES`
# type: set[str]
result = ...