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Python根据URL地址下载文件并保存至对应目录

引言

在编程中经常会遇到图片等数据集将图片等数据以URL形式存储在txt文档中，为便于后续的分析，需要将其下载下来，并按照文件夹分类存储。本文以Github中Alexander Kim提供的图片分类数据集为例，下载其提供的图片样本并分类保存
Python 3.6.5，Anaconda， VSCode

1. 下载数据集文件

建立项目文件夹，下载上述Github项目中的raw_data文件夹，并保存至项目目录中用python3.4画满天星。
## 2. 获取样本文件位置
编写get_doc_path.py，根据根目录位置，获取目录及其子目录所有数据集文件

import os
 
 
def get_file(root_path, all_files={}):
    '''
    递归函数，遍历该文档目录和子目录下的所有文件，获取其path
    '''
    files = os.listdir(root_path)
    for file in files:
        if not os.path.isdir(root_path + '/' + file):   # not a dir
            all_files[file] = root_path + '/' + file
        else:  # is a dir
            get_file((root_path+'/'+file), all_files)
    return all_files
 
 
if __name__ == '__main__':
    path = './raw_data'
    print(get_file(path))

3. 下载文件

3.1 读取url列表并

for filename, path in paths.items():
        print('reading file: {}'.format(filename))
        with open(path, 'r') as f:
            lines = f.readlines()
            url_list = []
            for line in lines:
                url_list.append(line.strip('\n'))
            print(url_list)

3.2 创建文件夹

foldername = "./picture_get_by_url/pic_download/{}".format(filename.split('.')[0])
if not os.path.exists(folder_path):
        print("Selected folder not exist, try to create it.")
        os.makedirs(folder_path)

3.3 下载图片

def get_pic_by_url(folder_path, lists):
    if not os.path.exists(folder_path):
        print("Selected folder not exist, try to create it.")
        os.makedirs(folder_path)
    for url in lists:
        print("Try downloading file: {}".format(url))
        filename = url.split('/')[-1]
        filepath = folder_path + '/' + filename
        if os.path.exists(filepath):
            print("File have already exist. skip")
        else:
            try:
                urllib.request.urlretrieve(url, filename=filepath)
            except Exception as e:
                print("Error occurred when downloading file, error message:")
                print(e)

4. 完整源码

4.1 get_doc_path.py

import os
 
 
def get_file(root_path, all_files={}):
    '''
    递归函数，遍历该文档目录和子目录下的所有文件，获取其path
    '''
    files = os.listdir(root_path)
    for file in files:
        if not os.path.isdir(root_path + '/' + file):   # not a dir
            all_files[file] = root_path + '/' + file
        else:  # is a dir
            get_file((root_path+'/'+file), all_files)
    return all_files
 
 
if __name__ == '__main__':
    path = './raw_data'
    print(get_file(path))
 

4.2 get_pic.py

import get_doc_path
import os
import urllib.request
 
 
def get_pic_by_url(folder_path, lists):
    if not os.path.exists(folder_path):
        print("Selected folder not exist, try to create it.")
        os.makedirs(folder_path)
    for url in lists:
        print("Try downloading file: {}".format(url))
        filename = url.split('/')[-1]
        filepath = folder_path + '/' + filename
        if os.path.exists(filepath):
            print("File have already exist. skip")
        else:
            try:
                urllib.request.urlretrieve(url, filename=filepath)
            except Exception as e:
                print("Error occurred when downloading file, error message:")
                print(e)
 
 
if __name__ == "__main__":
    root_path = './picture_get_by_url/raw_data'
    paths = get_doc_path.get_file(root_path)
    print(paths)
    for filename, path in paths.items():
        print('reading file: {}'.format(filename))
        with open(path, 'r') as f:
            lines = f.readlines()
            url_list = []
            for line in lines:
                url_list.append(line.strip('\n'))
            foldername = "./picture_get_by_url/pic_download/{}".format(filename.split('.')[0])
            get_pic_by_url(foldername, url_list)

4.3 运行结果

执行get_pic.py
当程序意外停止或再次执行时，程序会自动跳过文件夹中已下载的文件，继续下载未下载的内容

{‘urls_drawings.txt’: ‘./picture_get_by_url/raw_data/drawings/urls_drawings.txt’, ‘urls_hentai.txt’: ‘./picture_get_by_url/raw_data/hentai/urls_hentai.txt’, ‘urls_neutral.txt’: ‘./picture_get_by_url/raw_data/neutral/urls_neutral.txt’, ‘urls_porn.txt’: ‘./picture_get_by_url/raw_data/porn/urls_porn.txt’, ‘urls_sexy.txt’: ‘./picture_get_by_url/raw_data/sexy/urls_sexy.txt’}
reading file: urls_drawings.txt
Try downloading file: http://41.media.tumblr.com/xxxxxx.jpg
Try downloading file: http://41.media.tumblr.com/xxxxxx.jpg
Try downloading file: http://ak1.polyvoreimg.com/cgi/img-thing/size/l/tid/xxxxxx.jpg
Error occurred when downloading file, error message:
HTTP Error 502: No data received from server or forwarder
Try downloading file: http://akicocotte.weblike.jp/gaugau/xxxxxx.jpg
Try downloading file: http://animewriter.files.wordpress.com/2009/01/nagisa-xxxxxx-xxxxxx.jpg
Try downloading file: http://cdn.awwni.me/xxxxxx.jpg
Try downloading file: http://cdn.awwni.me/xxxxxx.jpg
Try downloading file: http://cdn.awwni.me/xxxxxx.jpg
Try downloading file: http://cdn.awwni.me/xxxxxx.jpg
Try downloading file: http://cdn.awwni.me/xxxxxx.jpg
Try downloading file: http://cdn.awwni.me/xxxxxx.jpg
Try downloading file: http://cdn.awwni.me/xxxxxx.jpg
Try downloading file: http://cdn.awwni.me/xxxxxx.jpg
Try downloading file: http://cdn.awwni.me/xxxxxx.jpg
Try downloading file: http://cdn.awwni.me/xxxxxx.jpg
Try downloading file: http://cdn.awwni.me/xxxxxx.jpg
Try downloading file: http://cdn.awwni.me/xxxxxx.jpg
Try downloading file: http://cdn.awwni.me/xxxxxx.jpg
Try downloading file: http://cdn.awwni.me/xxxxxx.jpg
Try downloading file: http://cdn.awwni.me/xxxxxx.jpg
Try downloading file: http://cdn.awwni.me/xxxxxx.jpg
Try downloading file: http://cdn.awwni.me/xxxxxx.jpg

后注：由于样本数据集内容的问题，上述地址以xxxxx代替具体地址，案例项目也已经失效，但是方法仍然可以借鉴

20.9.23更新：数据集地址：https://github.com/ZQ-Qi/nsfw_data_scrapper，单纯为了学习和实践本文代码的可以下载该数据集进行尝试