咨询flatten方法使用是否正确：列表扁平化未得预期字符数组

Hey there! Let's break down why your flatten approach isn't outputting the ['t','h','i','s','i','s'] result you're expecting, and how to fix it.

First, let's clarify a common gotcha: most standard flatten implementations don't split strings into individual characters. Here's why:

Flatten functions (whether you wrote your own, or use tools like itertools or NumPy) are designed to unpack nested container types (like lists, tuples, etc.). Strings are technically iterable, but nearly all flatten logic treats them as "atomic" elements—meaning they'll stay intact instead of getting split into characters. This is intentional, because otherwise you'd end up accidentally breaking strings apart when you don't want to (e.g., flattening ['hello', [1,2]] would turn into ['h','e','l','l','o',1,2], which is rarely desired).

Let's assume your input looks like this (super common scenario): #

Suppose your original list is something like ['this', 'is'], and you tried flattening it directly. A basic flatten function would return ['this', 'is'] instead of splitting the strings. That's exactly why your result doesn't match your expectation.

How to get the character array you want: #

If your goal is to turn a list of strings into a flat list of individual characters, you don't need a traditional flatten method—you can use a nested list comprehension instead:

original_list = ['this', 'is']
target_result = [char for string in original_list for char in string]
# Output: ['t','h','i','s','i','s']

If your input has deeper nesting (like [['this'], ['is']]), you can combine flattening the nested lists first, then splitting the strings:

nested_list = [['this'], ['is']]
# First flatten the nested lists to get ['this', 'is']
flattened_strings = [item for sublist in nested_list for item in sublist]
# Then split into characters
target_result = [char for s in flattened_strings for char in s]

So, was your flatten usage "correct"? #

It depends on what you passed to it and what the flatten function does. If you fed it a list of strings and expected it to split them into characters—then no, that's not how most flatten methods work. But if you had nested lists and your flatten function was only unpacking those (not touching strings), then the function worked as intended—you just needed an extra step to split the strings.

内容的提问来源于stack exchange，提问作者blue-sky