For anyone interested, I've written a humble program with a GUI that compares based on file size and binary chunks: github. Add a comment.
Active Oldest Votes. Fastest algorithm - x performance increase compared to the accepted answer really : The approaches in the other solutions are very cool, but they forget about an important property of duplicate files - they have the same file size.
Iterating on the solid answers given by nosklo and borrowing the idea of Raffi to have a fast hash of just the beginning of each file, and calculating the full one only on collisions in the fast hash, here are the steps: Buildup a hash table of the files, where the filesize is the key. For files with the same size, create a hash table with the hash of their first bytes; non-colliding elements are unique For files with the same hash on the first 1k bytes, calculate the hash on the full contents - files with matching ones are NOT unique.
The code:! Baseline - a directory with files, 32 mp4, - jpg, total size - Negatives: More disk access than the other versions - every file is accessed once for size stats that's cheap, but still is disk IO , and every duplicate is opened twice for the small first 1k bytes hash, and for the full contents hash Will consume more memory due to storing the hash tables runtime.
Todor Minakov Todor Minakov I updated this script for python3 with some small code improvements: gist. You should use tuples size, hash as keys, not the hash alone. If there are millions of files, the risk is not negligible. Futal Good point! I updated gist. On the contrary, it does work : ; but - it doesn't delete the files, it was never the intent - check the code, it just prints their names.
I didn't add it on purpose - in my case, I want to see which of the duplicates to actually keep. If you want to do it automatically - just add os. Show 7 more comments. Recursive folders version: This version uses the file size and a hash of the contents to find duplicates. Jakob Bowyer: Sure, the implementation is iterative. By "Recursive folders" I mean that it recurses the entire folder tree.
Example: open a cmd prompt, navigate to the folder and type: python myscript. Resurrecting this old post. This is a great script, but it fails if it comes up against a file which it does not have permission to access for example pagefile. How can the "for chunk in Show 3 more comments. FloPinguin 1 1 gold badge 5 5 silver badges 16 16 bronze badges.
For performance, you should probably change unique to be a set though it probably won't be a big factor unless there are lots of small files. Log file, you can copy the information to the Sfcdetails. To do this, follow these steps:.
Note The Sfcdetails. The file includes information about files that were not repaired by the System File Checker tool.
Verify the date and time entries to determine the problem files that were found the last time that you ran the System File Checker tool. How to manually replace a corrupted system file with a known good copy of the file. After you determine which system file was corrupted and could not be repaired through the detail information in the Sfcdetails.
To do this, follow these steps: Note You may be able to get a known good copy of the system file from another computer that is running the same version of Windows with your computer. You may perform a System File Checker process on that computer to make sure the system file that you intend to copy is a good copy. Take administrative ownership of the corrupted system file. To do this, at an elevated command prompt, copy and then paste or type the following command, and then press ENTER:.
Grant administrators full access to the corrupted system file. Replace the corrupted system file with a known good copy of the file. If the steps above don't work, you may need to reinstall Windows. For more info, see Windows 10 recovery options. Windows 8. Need more help? Expand your skills. Get new features first. Now loop file 2 through or less However most images are a non match with the first pixel check. Check just the diagonal and thats eliminates like 90 percent. So, I am thinking it can be done in less than a lifetime.
More like a minute or two with files. May have to try it to get convinced. The exact criteria will come to play Make a report, delete the duplicates or what? I tried this. GetPixel bmpTarget. Width - 1, 0. Dim di As New IO. Add fi. FullName Next. You can speed that up somewhat by comparing the filesize before starting, If the filesizes are not the same the images cannot be identical.
It is just a quicky to prove the concept. It has to be debugged. It will only run once right now then you have to restart etc. I am sure other issues will come up with more testing. Try it with files and see how long it takes. If less than a lifetime then maybe worth improving the speed PS I think there will be more required if there are more than one duplicate but I cant think that far ahead right now I haven't run this to check, but I would suspect a useful change might be to adjust the looping to:.
As I mentioned its just a concept. Depends on exactly what one has in mind for how many files, how large the images etc. These are not a lot of large images.
PS Razerz and I have played with this and as I recall using lockbits is like 10 times faster or more especially with large files like when x and over. Most of the images I used above were less than He knows the lockbits I am just beginning to get it. I know that I can do many recursive searches on a disk to get all files with their size, type of image per type of image.
If I sort then that collection on size, I can go through it and find which of those who have an equal value are different or equal.
Of course I should make the computer only bound to that process, If there is one image added during that time it is wrong. My experience with that recursive way on a current Microsoft OS has lead to many disappointments because of the many strange ways they made folders read only. Although that image software is not my thing, can I do it easily for one folder even if that one has subfolders. Just for kicks I tested v3 with images, several hundred over x pixels it takes 13 minutes.
So optimizing can cut that x 10 and more I think. I have never bothered implementing a lockbits version, although I am sure it is much faster, mainly because if I need to compare several thousand images I would usually let it run in the background while I get on with something more important. But if I was to do a lockbits I think t would be interesting to implement the checking as an unamanged memory block compare in assembler.
That would include forcing it to run in multiple threads with each thread running in a single core to optimise the caching and branch prediction! You might get a a small additional improvement by fully implementing the early exit - currently it only applies to the inner loop.
It is a balance of an extra test for each iteration of the the outer loop which is additional processing when the images match against unneeded albeit, probably brief iterations of the outer loop when the images don't match.
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