Update README.md
Signed-off-by: David Rotermund <54365609+davrot@users.noreply.github.com>
This commit is contained in:
parent
620d538b39
commit
656bfba7a5
1 changed files with 202 additions and 5 deletions
|
@ -64,10 +64,6 @@ for_stmt ::= "for" target_list "in" starred_list ":" suite
|
|||
["else" ":" suite]
|
||||
```
|
||||
|
||||
## for loop (enumerate)
|
||||
|
||||
XXXXXXXXX
|
||||
|
||||
## for loop (the truth)
|
||||
|
||||
{: .topic-optional}
|
||||
|
@ -75,6 +71,207 @@ This is an optional topic!
|
|||
|
||||
The for loop is not counting up itself. It uses the \_\_iter\_\_ & \_\_next\_\_ combo of a instance of a class or a generator via [yield](https://docs.python.org/3/reference/simple_stmts.html#the-yield-statement).
|
||||
|
||||
XXXXXXXXX
|
||||
### Class
|
||||
|
||||
```python
|
||||
class ClassIterExample:
|
||||
counter: int
|
||||
counter_max: int
|
||||
|
||||
def __init__(self):
|
||||
self.counter = 8
|
||||
self.counter_max = 12
|
||||
|
||||
def __iter__(self):
|
||||
return self
|
||||
|
||||
def __next__(self):
|
||||
if self.counter < self.counter_max:
|
||||
self.counter += 1
|
||||
else:
|
||||
raise StopIteration
|
||||
|
||||
important_result: int = self.counter**2
|
||||
|
||||
return f"Element: {self.counter}", important_result
|
||||
|
||||
|
||||
test_instance = ClassIterExample()
|
||||
|
||||
for i in test_instance:
|
||||
print(i)
|
||||
```
|
||||
|
||||
Output:
|
||||
|
||||
```python
|
||||
('Element: 9', 81)
|
||||
('Element: 10', 100)
|
||||
('Element: 11', 121)
|
||||
('Element: 12', 144)
|
||||
```
|
||||
|
||||
### Generator yield
|
||||
|
||||
```python
|
||||
from typing import Generator
|
||||
|
||||
|
||||
def do_more(min_value: int, max_value: int) -> Generator:
|
||||
for index in range(min_value, max_value):
|
||||
yield index**2
|
||||
|
||||
|
||||
for i in do_more(min_value=3, max_value=8):
|
||||
print(i)
|
||||
```
|
||||
|
||||
Output:
|
||||
|
||||
```python
|
||||
9
|
||||
16
|
||||
25
|
||||
36
|
||||
49
|
||||
```
|
||||
|
||||
|
||||
## for loop -- [enumerate](https://docs.python.org/3/library/functions.html#enumerate)
|
||||
|
||||
```python
|
||||
enumerate(iterable, start=0)
|
||||
```
|
||||
|
||||
If you need the index of the element then you can use enumerate:
|
||||
|
||||
```python
|
||||
for i in enumerate(range(10, 13)):
|
||||
print(i)
|
||||
```
|
||||
|
||||
Output:
|
||||
|
||||
```python
|
||||
(0, 10)
|
||||
(1, 11)
|
||||
(2, 12)
|
||||
```
|
||||
|
||||
{: .topic-optional}
|
||||
This is an optional topic!
|
||||
|
||||
```python
|
||||
for i in enumerate(range(10, 13)):
|
||||
print(i)
|
||||
else:
|
||||
print("*")
|
||||
print(i)
|
||||
```
|
||||
|
||||
Output:
|
||||
|
||||
```python
|
||||
(0, 10)
|
||||
(1, 11)
|
||||
(2, 12)
|
||||
*
|
||||
(2, 12)
|
||||
```
|
||||
|
||||
{: .topic-optional}
|
||||
This is an optional topic!
|
||||
|
||||
```python
|
||||
class ClassIterExample:
|
||||
counter: int
|
||||
counter_max: int
|
||||
|
||||
def __init__(self):
|
||||
self.counter = 8
|
||||
self.counter_max = 12
|
||||
|
||||
def __iter__(self):
|
||||
return self
|
||||
|
||||
def __next__(self):
|
||||
if self.counter < self.counter_max:
|
||||
self.counter += 1
|
||||
else:
|
||||
raise StopIteration
|
||||
|
||||
important_result: int = self.counter**2
|
||||
|
||||
return f"Element: {self.counter}", important_result
|
||||
|
||||
|
||||
test_instance = ClassIterExample()
|
||||
|
||||
for i in enumerate(test_instance):
|
||||
print(i)
|
||||
```
|
||||
|
||||
Output:
|
||||
|
||||
```python
|
||||
(0, ('Element: 9', 81))
|
||||
(1, ('Element: 10', 100))
|
||||
(2, ('Element: 11', 121))
|
||||
(3, ('Element: 12', 144))
|
||||
```
|
||||
|
||||
You see a tuple with the enumerate id as a first component and a second tuple as result from the iterator.
|
||||
|
||||
|
||||
## [break](https://docs.python.org/3/reference/simple_stmts.html#the-break-statement)
|
||||
|
||||
> break may only occur syntactically nested in a for or while loop, but not nested in a function or class definition within that loop.
|
||||
|
||||
> It terminates the nearest enclosing loop, skipping the optional else clause if the loop has one.
|
||||
|
||||
> If a for loop is terminated by break, the loop control target keeps its current value.
|
||||
|
||||
```python
|
||||
break_stmt ::= "break"
|
||||
```
|
||||
|
||||
```python
|
||||
for i in range(0, 5):
|
||||
if i == 2:
|
||||
break
|
||||
print(i)
|
||||
```
|
||||
|
||||
Output:
|
||||
|
||||
```python
|
||||
0
|
||||
1
|
||||
```
|
||||
|
||||
|
||||
## [continue](https://docs.python.org/3/reference/simple_stmts.html#the-continue-statement)
|
||||
|
||||
> continue may only occur syntactically nested in a for or while loop, but not nested in a function or class definition within that loop. It continues with the next cycle of the nearest enclosing loop.
|
||||
|
||||
```python
|
||||
continue_stmt ::= "continue"
|
||||
```
|
||||
|
||||
```python
|
||||
for i in range(0, 5):
|
||||
if i == 2:
|
||||
continue
|
||||
print(i)
|
||||
```
|
||||
|
||||
Output:
|
||||
|
||||
```python
|
||||
0
|
||||
1
|
||||
3
|
||||
4
|
||||
```
|
||||
|
||||
|
||||
|
|
Loading…
Reference in a new issue