#0116

Take Selected Columns

EasyNumPy15 min10 XP

Problem

Given a 2D NumPy array and list of column indexes, return only those columns in that order.

Why This Matters

Feature selection in NumPy often means selecting columns by index.

Function Signature

def take_columns(matrix, columns):

Examples

Example 1

Input[[1,2,3],[4,5,6]], columns=[2,0]

Output[[3,1],[6,4]]

Columns are returned in the requested order.

Constraints

Return the requested value exactly.
Handle the stated edge cases.
Keep the solution readable.

CodePython

import numpy as np

def take_columns(matrix, columns):
    """
    Input example: [[1,2,3],[4,5,6]], columns=[2,0]
    Return: [[3,1],[6,4]]
    Return the value from the function so the tests can compare it. Do not print unless the prompt asks.
    """
    # write your code here
    return matrix

import numpy as np

def take_columns(matrix, columns):
    """
    Input example: [[1,2,3],[4,5,6]], columns=[2,0]
    Return: [[3,1],[6,4]]
    Return the value from the function so the tests can compare it. Do not print unless the prompt asks.
    """
    # write your code here
    return matrix

Visible browser tests run here when available.

Testcases1 visible / 3 hidden categories

Core example

Input[[1,2,3],[4,5,6]], columns=[2,0]

Expected[[3,1],[6,4]]

Columns are returned in the requested order.

Hidden Test Categories

single columnall columns reversedempty column list