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import os |
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import re |
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import sys |
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from contextlib import contextmanager |
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import requests |
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from progressbar import (ProgressBar, Percentage, Bar, ETA, FileTransferSpeed, |
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Timer, UnknownLength) |
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from six.moves import zip, urllib |
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from ..exceptions import NeedURLPrefix |
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@contextmanager |
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def progress_bar(name, maxval): |
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"""Manages a progress bar for a download. |
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Parameters |
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---------- |
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name : str |
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Name of the downloaded file. |
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maxval : int |
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Total size of the download, in bytes. |
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""" |
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if maxval is not UnknownLength: |
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widgets = ['{}: '.format(name), Percentage(), ' ', |
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Bar(marker='=', left='[', right=']'), ' ', ETA(), ' ', |
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FileTransferSpeed()] |
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else: |
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widgets = ['{}: '.format(name), ' ', Timer(), ' ', FileTransferSpeed()] |
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bar = ProgressBar(widgets=widgets, max_value=maxval, fd=sys.stdout).start() |
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try: |
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yield bar |
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finally: |
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bar.update(maxval) |
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bar.finish() |
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def filename_from_url(url, path=None): |
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"""Parses a URL to determine a file name. |
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Parameters |
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---------- |
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url : str |
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URL to parse. |
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""" |
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r = requests.get(url, stream=True) |
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if 'Content-Disposition' in r.headers: |
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filename = re.findall(r'filename=([^;]+)', |
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r.headers['Content-Disposition'])[0].strip('"\"') |
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else: |
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filename = os.path.basename(urllib.parse.urlparse(url).path) |
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return filename |
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def download(url, file_handle, chunk_size=1024): |
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"""Downloads a given URL to a specific file. |
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Parameters |
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---------- |
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url : str |
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URL to download. |
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file_handle : file |
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Where to save the downloaded URL. |
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""" |
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r = requests.get(url, stream=True) |
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total_length = r.headers.get('content-length') |
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if total_length is None: |
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maxval = UnknownLength |
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else: |
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maxval = int(total_length) |
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name = file_handle.name |
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with progress_bar(name=name, maxval=maxval) as bar: |
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for i, chunk in enumerate(r.iter_content(chunk_size)): |
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if total_length: |
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bar.update(i * chunk_size) |
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file_handle.write(chunk) |
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def ensure_directory_exists(directory): |
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"""Create directory (with parents) if does not exist, raise on failure. |
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Parameters |
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---------- |
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directory : str |
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The directory to create |
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""" |
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if os.path.isdir(directory): |
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return |
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os.makedirs(directory) |
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def default_downloader(directory, urls, filenames, url_prefix=None, |
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clear=False): |
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"""Downloads or clears files from URLs and filenames. |
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Parameters |
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---------- |
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directory : str |
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The directory in which downloaded files are saved. |
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urls : list |
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A list of URLs to download. |
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filenames : list |
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A list of file names for the corresponding URLs. |
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url_prefix : str, optional |
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If provided, this is prepended to filenames that |
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lack a corresponding URL. |
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clear : bool, optional |
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If `True`, delete the given filenames from the given |
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directory rather than download them. |
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""" |
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# Parse file names from URL if not provided |
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for i, url in enumerate(urls): |
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filename = filenames[i] |
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if not filename: |
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filename = filename_from_url(url) |
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if not filename: |
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raise ValueError("no filename available for URL '{}'".format(url)) |
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filenames[i] = filename |
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files = [os.path.join(directory, f) for f in filenames] |
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if clear: |
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for f in files: |
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if os.path.isfile(f): |
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os.remove(f) |
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else: |
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print('Downloading ' + ', '.join(filenames) + '\n') |
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ensure_directory_exists(directory) |
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for url, f, n in zip(urls, files, filenames): |
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if not url: |
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if url_prefix is None: |
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raise NeedURLPrefix |
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url = url_prefix + n |
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with open(f, 'wb') as file_handle: |
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download(url, file_handle) |
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It is generally discouraged to redefine built-ins as this makes code very hard to read.