How can I detect if a file is binary (non-text) in Python?
How can I tell if a file is binary (non-text) in Python?
I am searching J.E.T OPTION（ジェットオプション）の評価 through a large set of files in Python, and keep getting matches in binary files. This makes the output look incredibly messy.
I know I could use grep -I , but I am doing more with the data than what grep allows for.
In the past, I would have just searched for characters greater than 0x7f , but utf8 and J.E.T OPTION（ジェットオプション）の評価 the like, make that impossible on modern systems. Ideally, the solution would be fast.
IF "in the past I would have just searched for characters greater than 0x7f" THEN J.E.T OPTION（ジェットオプション）の評価 you used to work with plain ASCII text THEN still no issue since ASCII text encoded as UTF-8 remains ASCII (i.e. no bytes > 127).
@ΤΖΩΤΖΙΟΥ: True, but I happen to know that the some of the files I am dealing with are utf8. I meant used to in the general sense, not in the specific J.E.T OPTION（ジェットオプション）の評価 sense of these files. :)
Only with probability. You can check if: 1) file contains \n 2) Amount of bytes between \n's is relatively small (this is NOT reliable)J.E.T OPTION（ジェットオプション）の評価 l 3) file doesn't bytes with value less than value of ASCCI "space" character (' ') - EXCEPT "\n" "\r" "\t" and zeroes.
The strategy that grep itself uses to J.E.T OPTION（ジェットオプション）の評価 J.E.T OPTION（ジェットオプション）の評価 identify binary files is similar to that posted by Jorge Orpinel below. Unless you set the -z option, it will just scan for a null character ( "\000" ) in the file. With -z , it scans for "\200" . Those interested and/or skeptical can check line 1126 of grep.c . Sorry, I couldn't find a webpage with the source code, but of course you can get it from gnu.org or via a distro.
P.S. As mentioned in the comments thread for Jorge's post, this strategy J.E.T OPTION（ジェットオプション）の評価 will give false positives for files containing, for example, UTF-16 text. Nonetheless, both git diff and GNU diff also use the same strategy. I'm not sure if it'J.E.T OPTION（ジェットオプション）の評価 s so prevalent because it's so much faster and easier than the alternative, or if it's just because of the relative rarity of UTF-16 files on J.E.T OPTION（ジェットオプション）の評価 systems which tend to have these utils installed.
21 Answers 21
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Interestingly enough, file(1) itself excludes 0x7f from consideration as well, so technically speaking you should be using bytearray([7,8,9,10,12,13,27]) + bytearray(range(0x20, 0x7f)) + bytearray(range(0x80, J.E.T OPTION（ジェットオプション）の評価 0x100)) instead. See Python, file(1) - Why are the numbers [7,8,9,10,12,13,27] and range(0x20, 0x100) used for determining text vs binary J.E.T OPTION（ジェットオプション）の評価 file and github.com/file/file/blob/…
@MarkRansom to make sure a file is closed, use the with -statement or call .close() method explicitly.
You can also use the mimetypes module:
It's fairly easy to compile a list of binary mime types. For example Apache distributes with a mime.types file that you could parse into a set of lists, binary and text and then check to see if the mime is in your text or binary list.
There is a similar question with some good answers here: stackoverflow.com/questions/1446549/… J.E.T OPTION（ジェットオプション）の評価 The answer based on an activestate recipe looks good to me, it allows a small proportion of non-printable characters (but no \0, for some reason).
This isn't a great answer only because the mimetypes module is not good for all files. I'm looking at a file now which system file reports as "UTF-8 Unicode text, with very long lines" but mimetypes.gest_type() will return (None, None). Also, Apache's mimetype list is a whitelist/subset. It is by no means a complete list of mimetypes. It cannot be used to classify all files as either text or non-text.
guess_types is based on the file name extension, not the real content as the Unix command "J.E.T OPTION（ジェットオプション）の評価 J.E.T OPTION（ジェットオプション）の評価 J.E.T OPTION（ジェットオプション）の評価 file" would do.
If you're using python3 with utf-8 it is straight forward, just open the file in text mode and stop processing if you get an UnicodeDecodeError . Python3 will use unicode when handling files in text mode (and bytearray in binary mode) - if your encoding can't decode arbitrary files it's quite likely that you will get UnicodeDecodeError .
@John Machin: Interestingly, git diff actually works this way, and sure enough, it detects UTF-16 files as binary.
Hunh.. GNU diff also works this way. It has similar issues with UTF-16 files. file does correctly detect the same files as UTF-16 text. I haven't checked out grep 's code, but it too detects UTF-16 files as binary.
+1 @John Machin: utf-16 is a character data according to file(1) that is not safe to print without conversion so this method is appropriate in this case.
-1 - I don't think 'contains a zero byte' is an adequate test for binary vs text, for example I can create a J.E.T OPTION（ジェットオプション）の評価 file containing all 0x01 bytes or repeat 0xDEADBEEF, but it is not a text file. The answer based on file(1) is better.
If it helps, many many binary J.E.T OPTION（ジェットオプション）の評価 types begin with a magic numbers. Here is a list of file signatures.
We can use python itself to check if a file is binary, because it fails if we try to open binary file in text mode
Aren't AVI video files binary? Or are you saying some AVI files get a return value of False from this is_binary()?
Here's a suggestion that uses the Unix file command:
It has the downsides of not being portable to Windows (unless you have something like the file J.E.T OPTION（ジェットオプション）の評価 command there), and having to spawn an external process for each file, which might not be palatable.
This broke my script :( Investigating, I found out that some conffiles are J.E.T OPTION（ジェットオプション）の評価 described by file as "Sendmail frozen configuration - version m"—notice the absence of the string "text". Perhaps use file -i ?
It is very simple and based on the J.E.T OPTION（ジェットオプション）の評価 code found in this stackoverflow question.
You can actually write this in 2 lines of code, however this package saves you from having to write and thoroughly test those 2 lines of code with all sorts of weird file types, cross-platform.
Usually you have to guess.
You can look at the extensions as one clue, if the J.E.T OPTION（ジェットオプション）の評価 files have them.
You can also recognise know binary formats, and ignore those.
Otherwise see what proportion of non-printable ASCII bytes you have and take a guess from that.
You can also try decoding from UTF-8 and see if that produces sensible output.
A shorter solution, with a UTF-16 warning:
Try using the currently maintained python-magic which is not the same module in @Kami Kisiel's answer. This does support all platforms including Windows however you will need the libmagic binary files. This is explained in the README.
Unlike the mimetypes module, it doesn't use the file's extension and instead inspects the contents of the file.
If you're not on Windows, you can use Python Magic to determine the filetype. Then you can check if it is a text/ mime type.
Here's a function that first checks if the file starts with a BOM and if not looks for a zero byte within the initial 8192 bytes:
Technically the check for the UTF-8 BOM is unnecessary because it should not contain zero bytes for all practical purpose. But as it is a very common encoding it's quicker to check for the BOM in the beginning instead of scanning all the 8192 bytes for 0.
Most of the programs consider the file to be binary (which is any file that is not "line-oriented") if it contains a NULL character.
Here is perl's version of pp_fttext() ( pp_sys.c ) implemented in Python:
Note also that this code was written to run on both Python 2 and Python 3 without changes.
I came here looking for exactly the same thing--a comprehensive solution provided by the standard library to detect binary or text. After reviewing the J.E.T OPTION（ジェットオプション）の評価 options people suggested, the nix file command looks to be the best choice (I'm only developing for linux boxen). Some others posted solutions using file but they are unnecessarily complicated in my opinion, so here's what I came up with:
It should go without saying, but your code that calls this function should make sure you J.E.T OPTION（ジェットオプション）の評価 J.E.T OPTION（ジェットオプション）の評価 J.E.T OPTION（ジェットオプション）の評価 J.E.T OPTION（ジェットオプション）の評価 J.E.T OPTION（ジェットオプション）の評価 J.E.T OPTION（ジェットオプション）の評価 can read a file before testing it, otherwise this will be mistakenly detect the file as binary.
I guess that the best solution is to use the guess_type J.E.T OPTION（ジェットオプション）の評価 function. It holds a list with several mimetypes and you can also include your own types. Here come the script that I did to solve my problem:
It is J.E.T OPTION（ジェットオプション）の評価 inside of a Class, as you can see based on the ustructure of the code. But you can pretty much change the things you want to implement it inside your application. It`s quite simple to use. The method getTextFiles returns a list object with all the text files that resides on the directory you pass in path variable.
If you have access to the file shell-command, shlex can help make the subprocess module more usable:
Or, you could also stick that in a for-loop to get output for all files in the current dir using:
or for all subdirs:
are you in unix? if so, then try:
The shell return values are inverted (0 is ok, so if it finds "text" then it will return a 0, and in Python that is a False expression).
For reference, the file command guesses a J.E.T OPTION（ジェットオプション）の評価 type based on the file's content. I'm not sure whether it pays any attention to the file extension.
This breaks if the path contains "text", tho. Make sure to rsplit at the last ':' (provided there's no colon in the file type description).
a slightly nicer version: is_binary_file = lambda filename: "text" in subprocess.check_output(["file", "-b", filename])
Simpler way is to check if the file consist NULL character ( \x00 ) by using in operator, for instance:
See below the complete example:
All of J.E.T OPTION（ジェットオプション）の評価 these basic methods were incorporated into a Python library: binaryornot. Install with pip.
From the documentation:
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