如何大声阅读Python列表推导? [英] How to read aloud Python List Comprehensions?

问题描述

我的问题是关于Python 列表理解的可读性.当我遇到具有复杂/嵌套列表理解的代码时，我发现我不得不重新阅读它们几次才能理解其意图.

My question is about Python List Comprehension readability. When I come across code with complex/nested list comprehensions, I find that I have to re-read them several times in order to understand the intent.

是否有一种直观的方法来朗读列表理解?似乎我应该从中间开始阅读"，然后阅读 if 条件(如果有)，然后阅读 表达式 最后.

Is there an intuitive way to read aloud list comprehensions? Seems like I should start "reading" from the middle, then read the if conditions (if any), and read the expression last.

这是我如何大声阅读下面的代码行，以便理解它:

Here's how I would read the follow line of code aloud, in order to understand it:

[(x, y) for x in [1,2,3] for y in [3,1,4] if x != y]

对于列表x中的每个元素和列表y中的每个元素，如果两个元素不相同，则创建元组列表."

"For each element in List x, and each element in List y, if the two elements are not the same, create a list of tuples."

我正在苦苦挣扎的两个例子: 您将如何大声阅读以下列表理解?

Two examples that I am struggling with: How would you read the following List Comprehensions aloud?

1. 来自堆栈溢出的另一个问题:[x for b in a for x in b]

Python文档具有以下示例: [[row[i] for row in matrix] for i in range(4)]

Python docs has this example: [[row[i] for row in matrix] for i in range(4)]

任何对大声朗读列表理解方式的建议或指针，都可以使意图变得更加清晰.

Any suggestions or pointers for ways to read aloud list comprehensions such that the intention becomes clearer is much appreciated.

推荐答案

我通常在脑海中将其展开为一个生成循环，例如

I usually unfold it in my mind into a generating loop, so for example

[(x, y) for x in [1,2,3] for y in [3,1,4] if x != y]

是生成器的列表理解

for x in [1,2,3]:
    for y in [3,1,4]:
        if x != y:
            yield (x, y)

---

示例1

[x for b in a for x in b]是对

---

Example #1

[x for b in a for x in b] is the comprehension for

for b in a:
    for x in b:
        yield x

a = [[1,2,3],[4,5,6]]的示例结果:[1, 2, 3, 4, 5, 6]

[[row[i] for row in matrix] for i in range(4)](请注意，内部表达式是另一种理解！):

[[row[i] for row in matrix] for i in range(4)] (note the inner expression is another comprehension!):

for i in range(4):
    yield [row[i] for row in matrix]

已展开

for i in range(4):
    l = []

    for row in matrix:
        l.append(row[i])

    yield l

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