chore: clean repository history

kb/python-course-kb-practical-python/wiki/exercises/6-13-generator-expressions.md

@@ -0,0 +1,50 @@
+---
+id: practical-python-6.13
+source_exercise_id: "6.13"
+title: "Generator Expressions"
+section: "6.4 More Generators"
+source_path: "06_Generators/04_More_generators.md"
+source_repo: "https://github.com/dabeaz-course/practical-python"
+source_commit: "93dca856b41c61a0a0f85ae334116e4c125629ea"
+student_visible_solution: false
+has_private_solution: false
+skip: false
+---
+
+# Exercise 6.13: Generator Expressions
+
+> Source: Practical Python Programming, `06_Generators/04_More_generators.md`.
+
+### Exercise 6.13: Generator Expressions
+
+Generator expressions are a generator version of a list comprehension.
+For example:
+
+```python
+>>> nums = [1, 2, 3, 4, 5]
+>>> squares = (x*x for x in nums)
+>>> squares
+<generator object <genexpr> at 0x109207e60>
+>>> for n in squares:
+...     print(n)
+...
+1
+4
+9
+16
+25
+```
+
+Unlike a list a comprehension, a generator expression can only be used once.
+Thus, if you try another for-loop, you get nothing:
+
+```python
+>>> for n in squares:
+...     print(n)
+...
+>>>
+```
+
+## 关联来源
+
+- [[summaries/04_More_generators]]