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Two questions here. I have a set of files which are usually UTF-8 with BOM. I’d like to convert them (ideally in place) to UTF-8 with no BOM. It seems like
codecs.StreamRecoder(stream, encode, decode, Reader, Writer, errors) would handle this. But I don’t really see any good examples on usage. Would this be the best way to handle this?
source files: Tue Jan 17$ file brh-m-157.json brh-m-157.json: UTF-8 Unicode (with BOM) text
Also, it would be ideal if we could handle different input encoding wihtout explicitly knowing (seen ASCII and UTF-16). It seems like this should all be feasible. Is there a solution that can take any known Python encoding and output as UTF-8 without BOM?
edit 1 proposed sol’n from below (thanks!)
fp = open('brh-m-157.json','rw') s = fp.read() u = s.decode('utf-8-sig') s = u.encode('utf-8') print fp.encoding fp.write(s)
This gives me the following error:
IOError: [Errno 9] Bad file descriptor
I’m being told in comments that the mistake is I open the file with mode ‘rw’ instead of ‘r+”https://stackoverflow.com/”r+b’, so I should eventually re-edit my question and remove the solved part.
Simply use the “utf-8-sig” codec:
fp = open("file.txt") s = fp.read() u = s.decode("utf-8-sig")
That gives you a
unicode string without the BOM. You can then use
s = u.encode("utf-8")
to get a normal UTF-8 encoded string back in
s. If your files are big, then you should avoid reading them all into memory. The BOM is simply three bytes at the beginning of the file, so you can use this code to strip them out of the file:
import os, sys, codecs BUFSIZE = 4096 BOMLEN = len(codecs.BOM_UTF8) path = sys.argv with open(path, "r+b") as fp: chunk = fp.read(BUFSIZE) if chunk.startswith(codecs.BOM_UTF8): i = 0 chunk = chunk[BOMLEN:] while chunk: fp.seek(i) fp.write(chunk) i += len(chunk) fp.seek(BOMLEN, os.SEEK_CUR) chunk = fp.read(BUFSIZE) fp.seek(-BOMLEN, os.SEEK_CUR) fp.truncate()
It opens the file, reads a chunk, and writes it out to the file 3 bytes earlier than where it read it. The file is rewritten in-place. As easier solution is to write the shorter file to a new file like newtover’s answer. That would be simpler, but use twice the disk space for a short period.
As for guessing the encoding, then you can just loop through the encoding from most to least specific:
def decode(s): for encoding in "utf-8-sig", "utf-16": try: return s.decode(encoding) except UnicodeDecodeError: continue return s.decode("latin-1") # will always work
An UTF-16 encoded file wont decode as UTF-8, so we try with UTF-8 first. If that fails, then we try with UTF-16. Finally, we use Latin-1 — this will always work since all 256 bytes are legal values in Latin-1. You may want to return
None instead in this case since it’s really a fallback and your code might want to handle this more carefully (if it can).
In Python 3 it’s quite easy: read the file and rewrite it with
s = open(bom_file, mode="r", encoding='utf-8-sig').read() open(bom_file, mode="w", encoding='utf-8').write(s)
import codecs import shutil import sys s = sys.stdin.read(3) if s != codecs.BOM_UTF8: sys.stdout.write(s) shutil.copyfileobj(sys.stdin, sys.stdout)
This is my implementation to convert any kind of encoding to UTF-8 without BOM and replacing windows enlines by universal format:
def utf8_converter(file_path, universal_endline=True): ''' Convert any type of file to UTF-8 without BOM and using universal endline by default. Parameters ---------- file_path : string, file path. universal_endline : boolean (True), by default convert endlines to universal format. ''' # Fix file path file_path = os.path.realpath(os.path.expanduser(file_path)) # Read from file file_open = open(file_path) raw = file_open.read() file_open.close() # Decode raw = raw.decode(chardet.detect(raw)['encoding']) # Remove windows end line if universal_endline: raw = raw.replace('\r\n', '\n') # Encode to UTF-8 raw = raw.encode('utf8') # Remove BOM if raw.startswith(codecs.BOM_UTF8): raw = raw.replace(codecs.BOM_UTF8, '', 1) # Write to file file_open = open(file_path, 'w') file_open.write(raw) file_open.close() return 0
I found this question because having trouble with
configparser.ConfigParser().read(fp) when opening files with UTF8 BOM header.
For those who are looking for a solution to remove the header so that ConfigPhaser could open the config file instead of reporting an error of:
File contains no section headers, please open the file like the following:
This could save you tons of effort by making the remove of the BOM header of the file unnecessary.
(I know this sounds unrelated, but hopefully this could help people struggling like me.)
You can use codecs.
import codecs with open("test.txt",'r') as filehandle: content = filehandle.read() if content[:3] == codecs.BOM_UTF8: content = content[3:] print content.decode("utf-8")