3.2. Sequence Tuple¶
3.2.1. Rationale¶
Immutable - cannot add, modify or remove items
3.2.2. Definition¶
Defining empty tuple with () is used more often, but tuple() is more explicit:
>>> data = ()
>>> data = tuple()
Can store elements of any type:
>>> data = (1, 2, 3)
>>> data = (1.1, 2.2, 3.3)
>>> data = (True, False)
>>> data = ('a', 'b', 'c')
>>> data = ('a', 1, 2.2, True, None)
Brackets are optional, but it's a good practice to always write them:
>>> data = (1, 2, 3)
>>> data = 1, 2, 3
Single element tuple require comma at the end (important!):
>>> data = (1,)
>>> type(data)
<class 'tuple'>
>>> data = (1)
>>> type(data)
<class 'int'>
Comma after last element of multi value tuple is optional:
>>> data = (1, 2)
>>> type(data)
<class 'tuple'>
>>> data = (1, 2,)
>>> type(data)
<class 'tuple'>
3.2.3. Type Casting¶
Builtin function tuple() converts argument to tuple
>>> data = 'abcd'
>>> tuple(data)
('a', 'b', 'c', 'd')
>>> data = ['a', 'b', 'c', 'd']
>>> tuple(data)
('a', 'b', 'c', 'd')
>>> data = ('a', 'b', 'c', 'd')
>>> tuple(data)
('a', 'b', 'c', 'd')
>>> tuple('a', 'b', 'c', 'd')
Traceback (most recent call last):
TypeError: tuple expected at most 1 argument, got 4
3.2.4. GetItem¶
More information in Sequence GetItem
More information in Sequence Slice
>>> data = ('a', 'b', 'c', 'd')
>>> data[0]
'a'
>>> data[1]
'b'
>>> data[2]
'c'
>>> data[3]
'd'
3.2.5. Tuple or Int, Float, Str¶
>>> x = 1 # int
>>> x = 1. # float
>>> x = 1, # tuple
>>> x = (1) # int
>>> x = (1.) # float
>>> x = (1,) # tuple
>>> x = 'one' # str
>>> x = 'one', # tuple
>>> x = 'one'.
Traceback (most recent call last):
SyntaxError: invalid syntax
>>> x = (12) # int
>>> x = (1.2) # float
>>> x = (1,2) # tuple
>>> x = 1.,1. # tuple
>>> x = 1.,.1 # tuple
>>> x = .1,1. # tuple
3.2.6. Tuple or List¶
Both:
ordered
possible to getitem and slice
elements can be duplicated
elements of any types
Tuple:
immutable
one contingent block of data in memory
List:
mutable
implemented in memory as list of pointers to objects
objects are scattered in memory
Memory Footprint:
>>> from sys import getsizeof
>>>
>>> a = [1, 2, 3]
>>> b = (1, 2, 3)
>>>
>>> getsizeof(a)
120
>>>
>>> getsizeof(b)
64
Figure 3.1. Define tuple¶
Figure 3.2. Define list¶
Figure 3.3. Define str, tuple and list¶
3.2.7. Assignments¶
"""
* Assignment: Sequence Tuple Create
* Complexity: easy
* Lines of code: 1 lines
* Time: 2 min
English:
1. Create tuple `result` with elements:
a. `'a'`
b. `1`
c. `2.2`
2. Compare result with "Tests" section (see below)
Polish:
1. Stwórz tuple `result` z elementami:
a. `'a'`
b. `1`
c. `2.2`
2. Porównaj wyniki z sekcją "Tests" (patrz poniżej)
Tests:
>>> type(result)
<class 'tuple'>
>>> len(result)
3
>>> 'a' in result
True
>>> 1 in result
True
>>> 2.2 in result
True
"""
# Given
result = ... # with 'a' and 1 and 2.2
"""
* Assignment: Sequence Tuple Select
* Complexity: easy
* Lines of code: 1 lines
* Time: 5 min
English:
1. Use data from "Given" section (see below)
2. Create a `tuple` representing all species
3. To convert table use multiline select with `alt` key in your IDE
4. Do not use `slice`, `getitem`, `for`, `while` or any other control-flow statement
5. Compare result with "Tests" section (see below)
Polish:
1. Użyj danych z sekcji "Given" (patrz poniżej)
2. Stwórz `tuple` z nazwami gatunków
3. Do konwersji tabelki wykorzystaj zaznaczanie wielu linijek za pomocą klawisza `alt` w Twoim IDE
4. Nie używaj `slice`, `getitem`, `for`, `while` lub jakiejkolwiek innej instrukcji sterującej
5. Porównaj wyniki z sekcją "Tests" (patrz poniżej)
Hints:
* `ALT` + `left mouse button` = multiple select
* `ALT` + `SHIFT` + `left mouse button drag` = vertical selection
Tests:
>>> type(result)
<class 'tuple'>
>>> all(type(x) is str for x in result)
True
>>> ('sepal_length' not in result
... and 'sepal_width' not in result
... and 'petal_length' not in result
... and 'petal_width' not in result
... and 'species' not in result)
True
>>> len(result)
5
>>> result.count('virginica')
2
>>> result.count('setosa')
1
>>> result.count('versicolor')
2
"""
# Given
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']
"""
* Assignment: Sequence Tuple Mean
* Complexity: medium
* Lines of code: 8 lines
* Time: 8 min
English:
1. Use data from "Given" section (see below)
2. Calculate mean for each numerical values column
3. To convert table use multiline select with `alt` key in your IDE
7. Do not use `str.split()`, `slice`, `getitem`, `for`, `while` or any other control-flow statement
5. Compare result with "Tests" section (see below)
Polish:
1. Użyj danych z sekcji "Given" (patrz poniżej)
2. Wylicz średnią arytmetyczną dla każdej z kolumn numerycznych
3. Do konwersji tabelki wykorzystaj zaznaczanie wielu linijek za pomocą klawisza `alt` w Twoim IDE
4. Nie używaj `str.split()`, `slice`, `getitem`, `for`, `while` lub jakiejkolwiek innej instrukcji sterującej
5. Porównaj wyniki z sekcją "Tests" (patrz poniżej)
Hints:
* `mean = sum(...) / len(...)`
* `ALT` + `left mouse button` = multiple select
* `ALT` + `SHIFT` + `left mouse button drag` = vertical selection
* `ALT` + `SHIFT` + `right` = select word to the right (macOS)
* `ALT` + `SHIFT` + `left` = select word to the left (macOS)
* `CTRL` + `SHIFT` + `right` = select word to the right (Windows)
* `CTRL` + `SHIFT` + `left` = select word to the left (Windows)
* `CTRL` + `right` = jump over the word to the right
* `CTRL` + `left` = jump over the word to the left
* `CTRL` + `ALT` + L = Reformat Code on Windows
* `CMD` + `ALT` + L = Reformat Code on macOS
Tests:
>>> type(sepal_length)
<class 'float'>
>>> type(sepal_width)
<class 'float'>
>>> type(petal_length)
<class 'float'>
>>> type(petal_width)
<class 'float'>
>>> sepal_length
5.859999999999999
>>> sepal_width
3.0200000000000005
>>> petal_length
4.14
>>> petal_width
1.34
"""
# Given
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']