如何用列表推导式替代for循环实现列表创建与元素分组？

Absolutely—list comprehensions are ideal for replacing loops that exist solely to build a list. They’re more concise, readable (once you’re familiar with them), and often perform better than equivalent for loops with append() calls.

General Example #

If you have a loop like this:

my_list = []
for x in range(10):
    my_list.append(x * 2)

You can rewrite it in one line with a list comprehension:

my_list = [x * 2 for x in range(10)]

Your Specific Grouping Problem #

First, let’s fix a small bug in your original loop: right now, you’re using values[i:i+9], which creates overlapping slices once i is greater than 0 (e.g., i=1 gives elements 1-10 instead of the second full row of 9 elements). You should use n dynamically and calculate slice bounds as i*n to (i+1)*n instead.

Here’s the corrected for loop:

def group(values, n):
    grouped_values = []
    for i in range(len(values) // n):
        grouped_values.append(values[i*n : (i+1)*n])
    return grouped_values

And here’s the equivalent list comprehension version—cleaner and more compact:

def group(values, n):
    return [values[i*n : (i+1)*n] for i in range(len(values) // n)]

This works because:

• len(values) // n gives the exact number of rows (since you confirmed len(values) is divisible by n)
• For each i in that range, we take a slice of values starting at i*n (the start of the row) and ending at (i+1)*n (the end of the row)
• The list comprehension collects all these slices into the final grouped list, which matches your expected output perfectly.

Testing this with your values and n=9 will produce exactly the grouped_values you provided.

内容的提问来源于stack exchange，提问作者Michael