List index out of range in visualize_cv2.py

I want to launch mask-rcnn model from visualize_cv2.py. My goal is train only on 1 element from class_names – person. For this I create class_names1(added full code from this python file for better understanding):

import cv2
import numpy as np
import os
import sys
import coco
import utils
import model as modellib

ROOT_DIR = os.getcwd()
MODEL_DIR = os.path.join(ROOT_DIR, "logs")
COCO_MODEL_PATH = os.path.join(ROOT_DIR, "mask_rcnn_coco.h5")
if not os.path.exists(COCO_MODEL_PATH):
    utils.download_trained_weights(COCO_MODEL_PATH)


class InferenceConfig(coco.CocoConfig):
    GPU_COUNT = 1
    IMAGES_PER_GPU = 1


config = InferenceConfig()
config.display()

model = modellib.MaskRCNN(
    mode="inference", model_dir=MODEL_DIR, config=config
)
model.load_weights(COCO_MODEL_PATH, by_name=True)
class_names = [
        'BG', 'person', 'bicycle', 'car', 'motorcycle', 'airplane',
        'bus', 'train', 'truck', 'boat', 'traffic light',
        'fire hydrant', 'stop sign', 'parking meter', 'bench', 'bird',
        'cat', 'dog', 'horse', 'sheep', 'cow', 'elephant', 'bear',
        'zebra', 'giraffe', 'backpack', 'umbrella', 'handbag', 'tie',
        'suitcase', 'frisbee', 'skis', 'snowboard', 'sports ball',
        'kite', 'baseball bat', 'baseball glove', 'skateboard',
        'surfboard', 'tennis racket', 'bottle', 'wine glass', 'cup',
        'fork', 'knife', 'spoon', 'bowl', 'banana', 'apple',
        'sandwich', 'orange', 'broccoli', 'carrot', 'hot dog', 'pizza',
        'donut', 'cake', 'chair', 'couch', 'potted plant', 'bed',
        'dining table', 'toilet', 'tv', 'laptop', 'mouse', 'remote',
        'keyboard', 'cell phone', 'microwave', 'oven', 'toaster',
        'sink', 'refrigerator', 'book', 'clock', 'vase', 'scissors',
        'teddy bear', 'hair drier', 'toothbrush'
    ]
class_names1 = class_names[1]

def random_colors(N):
    np.random.seed(1)
    colors = [tuple(255 * np.random.rand(3)) for _ in range(N)]
    return colors


colors = random_colors(len(class_names))
class_dict = {
    name: color for name, color in zip(class_names, colors)
}


def apply_mask(image, mask, color, alpha=0.5):
    """apply mask to image"""
    for n, c in enumerate(color):
        image[:, :, n] = np.where(
            mask == 1,
            image[:, :, n] * (1 - alpha) + alpha * c,
            image[:, :, n]
        )
    return image


def display_instances(image, boxes, masks, ids, names, scores):
    """
        take the image and results and apply the mask, box, and Label
    """
    n_instances = boxes.shape[0]

if not n_instances:
    print('NO INSTANCES TO DISPLAY')
else:
    assert boxes.shape[0] == masks.shape[-1] == ids.shape[0]

for i in range(n_instances):
    if not np.any(boxes[i]):
        continue

    y1, x1, y2, x2 = boxes[i]
    label = names[ids[i]]
    color = class_dict[label]
    score = scores[i] if scores is not None else None
    caption = '{} {:.2f}'.format(label, score) if score else label
    mask = masks[:, :, i]

    image = apply_mask(image, mask, color)
    image = cv2.rectangle(image, (x1, y1), (x2, y2), color, 2)
    image = cv2.putText(
        image, caption, (x1, y1), cv2.FONT_HERSHEY_COMPLEX, 0.7, color, 2
    )

return image


 if __name__ == __main__:


capture = cv2.VideoCapture(0)


# these 2 lines can be removed if you dont have a 1080p camera.
#capture.set(cv2.CAP_PROP_FRAME_WIDTH, 1920)
#capture.set(cv2.CAP_PROP_FRAME_HEIGHT, 1080)

while True:
    ret, frame = capture.read()
    results = model.detect([frame], verbose=0)
    r = results[0]
    frame = display_instances(
        frame, r['rois'], r['masks'], r['class_ids'], class_names, r['scores']
    )
    cv2.imshow('frame', frame)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

capture.release()
cv2.destroyAllWindows()

But if I run it, I get an error:

Traceback (most recent call last):

File "visualize_cv2.py", line 86, in display_instances
label = names[ids[i]]
IndexError: string index out of range

As I thinking, I need to change this line(86) to something. But don’t understand how (I`m newbie in python).