如何解决这种类型的KeyError？
如何解决这种类型的KeyError？
提问于 2019-06-25 08:26:07
我正在尝试编写一个程序来抓取图像，以创建用于神经网络的数据集，但是我遇到了一些问题
代码如下：
from imutils import paths
import argparse
import requests
import cv2
import os
ap = argparse.ArgumentParser()
ap.add_argument("-u", "--C:/Users/artus/datasets/urls.txt",
required=False, help="path containing URLs")
ap.add_argument("-o", "--C:/Users/artus/datasets/ShoesImage",
required=False, help="folder for downloaded images")
args = vars(ap.parse_args())
# grab the list of URLs from the input file, then initialize the
# total number of images downloaded thus far
rows = open(args["urls"]).read().strip().split("\n")
total = 0在执行时，它应该从urls.txt文件中指定的urls下载所有图像，但是我得到了这个错误：
Traceback (most recent call last):
File "C:/Users/artus/untitled5/imagescraping.py", line 16, in <module>
rows = open(args["urls"]).read().strip().split("\n")
KeyError: 'urls'回答 2
Stack Overflow用户
发布于 2019-06-25 08:37:01
add_argument的第二个参数是参数的“长名称”。对于第一个参数，您将传递--urls，然后argparse将使用户传递的值作为args["urls"]可用
# ...
ap.add_argument("-u", "--urls", type=str,
required=False, help="path containing URLs")然后，在命令行中，传入参数：
python imagescraping.py --urls C:/Users/artus/datasets/urls.txt此外，我认为您不需要将其包装在vars中。
Stack Overflow用户
发布于 2019-06-25 08:48:04
当我将argparse代码复制-n-粘贴到脚本时：
import argparse
ap = argparse.ArgumentParser()
ap.add_argument("-u", "--C:/Users/artus/datasets/urls.txt",
required=False, help="path containing URLs")
ap.add_argument("-o", "--C:/Users/artus/datasets/ShoesImage",
required=False, help="folder for downloaded images")
args = ap.parse_args()
print(args)不带参数地调用它：
0923:~/mypy$ python3 stack56745387.py
Namespace(**{'C:/Users/artus/datasets/ShoesImage': None, 'C:/Users/artus/datasets/urls.txt': None})并寻求帮助：
1743:~/mypy$ python3 stack56745387.py -h
usage: stack56745387.py [-h] [-u C:/USERS/ARTUS/DATASETS/URLS.TXT]
[-o C:/USERS/ARTUS/DATASETS/SHOESIMAGE]
optional arguments:
-h, --help show this help message and exit
-u C:/USERS/ARTUS/DATASETS/URLS.TXT, --C:/Users/artus/datasets/urls.txt C:/USERS/ARTUS/DATASETS/URLS.TXT
path containing URLs
-o C:/USERS/ARTUS/DATASETS/SHOESIMAGE, --C:/Users/artus/datasets/ShoesImage C:/USERS/ARTUS/DATASETS/SHOESIMAGE
folder for downloaded images您可能希望"--C:/Users/artus/datasets/urls.txt“类似于默认值，但您将其定义为long标志和参数的dest。(设置中没有将urls指定为所需的dest或密钥。)
你必须使用它作为：
1750:~/mypy$ python3 stack56745387.py --C:/Users/artus/datasets/urls.txt foobar
Namespace(**{'C:/Users/artus/datasets/ShoesImage': None, 'C:/Users/artus/datasets/urls.txt': 'foobar'})将代码更改为：
import argparse
ap = argparse.ArgumentParser()
ap.add_argument("-u", "--urls", default="C:/Users/artus/datasets/urls.txt",
required=False, help="path containing URLs (default: %(default)s)")
ap.add_argument("-o", "--images",default="C:/Users/artus/datasets/ShoesImage",
required=False, help="folder for downloaded images (default: %(default)s)")
args = ap.parse_args()
print(args)
1802:~/mypy$ python3 stack56745387.py -h
usage: stack56745387.py [-h] [-u URLS] [-o IMAGES]
optional arguments:
-h, --help show this help message and exit
-u URLS, --urls URLS path containing URLs (default:
C:/Users/artus/datasets/urls.txt)
-o IMAGES, --images IMAGES
folder for downloaded images (default:
C:/Users/artus/datasets/ShoesImage)
1803:~/mypy$ python3 stack56745387.py --urls foobar
Namespace(images='C:/Users/artus/datasets/ShoesImage', urls='foobar')现在，您可以使用args.urls或vars(args)['urls']。
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原文链接：
https://stackoverflow.com/questions/56745387
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