https://github.com/ajithvcoder/session_11_iterablesanditerators_1
https://github.com/ajithvcoder/session_11_iterablesanditerators_1
Last synced: 3 months ago
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- Host: GitHub
- URL: https://github.com/ajithvcoder/session_11_iterablesanditerators_1
- Owner: ajithvcoder
- Created: 2021-07-23T16:19:38.000Z (almost 4 years ago)
- Default Branch: master
- Last Pushed: 2021-07-23T16:28:51.000Z (almost 4 years ago)
- Last Synced: 2025-01-12T19:28:49.446Z (4 months ago)
- Language: Python
- Size: 3.91 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
### Session 11 - Iterables and Iterators - I
Google Colab - [here](https://colab.research.google.com/drive/1hEFlhwuSk2q4kCKAXqZdj83YMD3H3aEX?usp=sharing)
#### Iterator
iterator is a object that helps to iterate over iterable objects like list, tuples. it uses __iter__ for initalization and uses next() method for iteration
```
def __iter__(self):
print("Calling PolygonIterator instance __iter__")
return self
```
it is used when below function is done
```
polygons = Polygons(6, 10)
iter_poly = iter(polygons)
```
#### next()
```
def __next__(self):
print("Calling PolygonIterator __next__")
if self._index >= len(self._poly_obj):
raise StopIteration
else:
item = self._poly_obj._polygons[self._index]
self._index += 1
return item
```
next() is used to fetch the next item(iterable) in a iterator. When it has fetched all the objects it raises a exception StopIteration. once all the items are exhausted , exception is raised and it denotes end of iterator.
#### getitem()
```
def __getitem__(self, num) -> 'list':
"""
:param num: edges of a polygon
:type num: int
:return class:
"""
return self._polygons[num]
```
getitem() is used to fetch a particular item in a list and also it helps while forming a new list
#### Iterable
Even when we iterate over a object again and again with for loop it should not get exhausted i.e there should be no need for re-initalization
```
polygons = Polygons(4, 10)
polygons_list = []
for poly in polygons:
polygons_list.append(poly)
print(poly)
for poly in polygons:
polygons_list.append(poly)
print(poly)
```
#### list()
Even when we call the object with list(obj) it should apt number of outputs
```
polygons = Polygons(10, 10)
assert len(list(polygons)) == 8
```