如何从obj文件中删除除一种颜色之外的所有颜色

def filter_colors(obj_file_path, target_color):
    filtered_vertices = []
    
    with open(obj_file_path, 'r') as obj_file:
        for line in obj_file:
            if line.startswith('v '):
                vertex = line.strip().split(' ')
                color = vertex[3:]  # Assuming color is specified as RGB values
                if color == target_color:
                    filtered_vertices.append(line)
                else:
                    # Set color to target_color
                    vertex[3:] = target_color
                    filtered_vertices.append(' '.join(vertex))
            else:
                filtered_vertices.append(line)
    
    # Write filtered vertices to a new obj file
    filtered_obj_file_path = obj_file_path.replace('.obj', '_filtered.obj')
    with open(filtered_obj_file_path, 'w') as filtered_obj_file:
        filtered_obj_file.writelines(filtered_vertices)
    
    return filtered_obj_file_path