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EX.10

練習10

This week’s exercise is going to be revisiting an old exercise (see Exercise 5), except require the solution in a different way.

Take two lists, say for example these two:

本週的練習將重溫舊的練習（請參閱練習5），只是需要以其他方式解決。

拿兩個列表，舉例來說，這兩個：

	a = [1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89]
	b = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13]

and write a program that returns a list that contains only the elements that are common between the lists (without duplicates). Make sure your program works on two lists of different sizes. Write this ~~in one line of Python~~ using at least one list comprehension. (Hint: Remember list comprehensions from Exercise 7).

並編寫一個程序，該程序返回一個列表，該列表僅包含列表之間的公共元素（無重複項）。確保您的程序可以在兩個不同大小的列表上運行。使用至少一個列表理解~~語句在一行Python中~~ 編寫。（提示：記住練習7中的列表理解）。

The original formulation of this exercise said to write the solution using one line of Python, but a few readers pointed out that this was impossible to do without using sets that I had not yet discussed on the blog, so you can either choose to use the original directive and read about the set command in Python 3.3, or try to implement this on your own and use at least one list comprehension in the solution.

並編寫一個程序，該程序返回一個列表，該列表僅包含列表之間的公共元素（無重複項）。確保您的程序可以在兩個不同大小的列表上運行。使用至少一個列表理解~~語句在一行Python中~~ 編寫。（提示：記住練習7中的列表理解）。

Extra:

額外：

Randomly generate two lists to test this
隨機生成兩個列表進行測試

Discussion

討論區

Concepts for this week:

本週的概念：

List comprehensions
清單理解
Random numbers, continued
隨機數，續

List comprehensions

清單理解

We already discussed list comprehensions in Exercise 7, but they can be made much more complicated.

我們已經在練習7中討論了列表理解，但是可以使它們複雜得多。

For example:

例如:

	x = [1, 2, 3]
	y = [5, 10, 15]
	allproducts = [a*b for a in x for b in y]

At the end of this piece of code, allproducts will contain the list [5, 10, 15, 10, 20, 30, 15, 30, 45]. So you can put multiple for loops inside the comprehension. But you can also add more complicated conditionals:

在這段代碼的最後，allproducts將包含list [5, 10, 15, 10, 20, 30, 15, 30, 45]。因此，您可以在理解中放入多個for循環。但是您還可以添加更複雜的條件：

	x = [1, 2, 3]
	y = [5, 10, 15]
	customlist = [a*b for a in x for b in y if a*b%2 != 0]

Now customlist contains [5, 15, 15, 45] because only the odd products are added to the list.

In general, the list comprehension takes the form:

現在customlist包含，[5, 15, 15, 45]因為僅將奇數產品添加到列表中。

通常，列表理解採用以下形式：

	[EXPRESSION FOR_LOOPS CONDITIONALS]

as shown in the examples above.

如以上示例所示。

Random numbers, continued

隨機數，續

Try to use the Python random documentation to figure out how to generate a random list. As a hint look below:

嘗試使用Python隨機文檔來弄清楚如何生成隨機列表。提示如下：

	a = random.sample(range(100), 5)

This line of code will leave a containing a list of 5 random numbers from 0 to 99.

這行代碼將a包含從0到99的5個隨機數的列表。

Check Primality Functions

檢查基本功能

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