How do you download multiple files in python?
Automating file downloads can save a lot of time. There are several ways for automating file downloads in Python. The easiest way to download files is using a simple Python loop to iterate through a list of URLs to download. This serial approach can work well with a few small files, but if you are downloading many files or large files, you’ll want to use a parallel approach to maximize your computational resources. Show
With a parallel file download routine, you can download multiple files simultaneously and save a considerable amount of time. The tutorial demonstrates how to develop a generic file download function in Python and apply it to download multiple files with serial and parallel approaches. The code in this tutorial uses only modules available from the Python standard library, so no installations are required. Import modulesFor this example, we only need the We’ll also import the
Define URLs and filenamesI’ll demonstrate parallel file downloads in Python using gridMET NetCDF files that contain daily precipitation data for the United States. Here, I specify the URLs to four files in a list. In other applications, you may programmatically generate a list of files to download.
Each URL must be associated with its download location. Here, I’m downloading the files to the Windows ‘Downloads’ directory. I’ve hardcoded the filenames in a list for simplicity and transparency. Given your application, you may want to write code that will parse the input URL and download it to a specific directory.
Multiprocessing requires parallel functions to have only one argument (there are some workarounds, but we won’t get into that here). To download a file we’ll need to pass two arguments, a URL and a filename. So we’ll zip the
Function to download a URLNow that we have specified the URLs to download and their associated filenames, we need a function to download the URLs ( We’ll pass one argument ( Now create a try statement in which the URL is retrieved and written to the file after it is created. When the file is written the URL and download time are returned. If an exception occurs a message is printed. The
Download multiple files with a Python loopTo download the list of URLs to the associated files, loop through the iterable ( The total time to download all URLs will print after all downloads have been completed.
Output:
It took between 11 and 16 seconds to download the individual files. The total download time was a little less than one minute. Your download times will vary based on your specific network connection. Let’s compare this serial (loop) approach to the parallel approach below. To start, create a function
( Next, get the number of CPUs available for processing. This will determine the number of threads to run in parallel. Now use the Thus, if we have four files and four threads all files can be downloaded at the same time instead of waiting for one download to finish before the next starts. This can save a considerable amount of processing time. In the final part of the
Once the
Output:
Notice that it took longer to download each individual file with the approach. This may be a result of changing network speed, or overhead required to map the downloads to their respective threads. Even though the individual files took longer to download, the parallel method resulted in a 50% decrease in total download time. You can see how parallel processing can greatly reduce processing time for multiple files. As the number of files increases, you will save much more time by using a parallel download approach. ConclusionAutomating file download in your development and analysis routines can save you a lot of time. As demonstrated by this tutorial implementing a parallel download routine can greatly decrease file acquisition time if you require many files or large files. Learn GIS From Industry ProfessionalsWhether you’re looking to take your GIS skills to the next level, or just getting started with GIS, we have a course for you! We’re constantly creating and curating more courses to help you improve your geospatial skills. All of our courses are taught by industry professionals and include step-by-step video instruction so you don’t get lost in YouTube videos and blog posts, downloadable data so you can reproduce everything the instructor does, and code you can copy so you can avoid repetitive typing How do I download multiple files in Python?Download multiple files in parallel with Python
To start, create a function ( download_parallel ) to handle the parallel download. The function ( download_parallel ) will take one argument, an iterable containing URLs and associated filenames (the inputs variable we created earlier).
How do I download multiple files at once?Hold CTRL and click on the files you want to download. Once you have selected the files you want, right click on the last file you selected and select download.
How do I download a file using Python?To download a file from a URL using Python follow these three steps:. Install requests module and import it to your project.. Use requests. get() to download the data behind that URL.. Write the file to a file in your system by calling open().. How do you download multiple images in Python?Method Two: How To Download Multiple Images From Many HTML Web Pages. Download the HTML content of every web page.. Extract all of the image URLs for every page.. Create the file names.. Check to see if the image status code is 200.. Write all of images to your local computer.. |