Python中如何基于数组索引截取列表？实操问题求助

It looks like you're trying to pull specific elements from your list using indices stored in a numpy array, but your current code has a couple of issues that are preventing it from working as expected. Let's break down what's going wrong and fix it.

What's Wrong With Your Current Code #

1. Undefined Variable: You reference X but haven't defined it—this is likely a typo for your vars list.
2. Incorrect Index Check: Your new_L is a tuple containing a numpy array (like (array([1,5,7]),)), so checking if i in new_L is looking for the index in the tuple itself, not the array inside it.
3. No Collection of Results: You're just printing indices instead of gathering the corresponding elements from your list.
   Side note: It's best to avoid using vars as a variable name since it's a built-in Python function. I've renamed it to vars_list in the examples below to prevent any conflicts.

Simple Solutions to Get Your Desired Output #

First, let's set up your original variables properly and extract the actual indices array from the tuple:

import numpy as np

# Your original list of column names
vars_list = ['age','balance','day','duration','campaign','pdays','previous','job_admin.','job_blue-collar']
# Your indices wrapped in a tuple
new_L = (np.array([1, 5, 7], dtype=int64),)

# Extract the indices array from the tuple
indices = new_L[0]

Solution 1: List Comprehension (Most Pythonic)

This is the cleanest and most readable way to get your desired list:

result = [vars_list[i] for i in indices]
print(result)  # Output: ['balance','pdays','job_admin.']

Solution 2: Using Numpy Array Indexing

If you prefer working with numpy, convert your list to a numpy array and index directly:

vars_array = np.array(vars_list)
result = vars_array[indices].tolist()
print(result)  # Same output as above

Solution 3: Fixed Loop Approach

If you want to stick with a loop, here's how to adjust your code to collect the correct elements:

result = []
for i in indices:
    result.append(vars_list[i])
print(result)

All three methods will give you the exact output you're looking for. The list comprehension is generally the most efficient and idiomatic choice for this kind of task.

内容的提问来源于stack exchange，提问作者Neil