I have a list of bytes as integers, which is something like
[120, 3, 255, 0, 100]
How can I write this list to a file as binary?
Would this work?
newFileBytes = [123, 3, 255, 0, 100]
# make file
newFile = open("filename.txt", "wb")
# write to file
newFile.write(newFileBytes)
This question is related to
python
As of Python 3.2+, you can also accomplish this using the to_bytes
native int method:
newFileBytes = [123, 3, 255, 0, 100]
# make file
newFile = open("filename.txt", "wb")
# write to file
for byte in newFileBytes:
newFile.write(byte.to_bytes(1, byteorder='big'))
I.e., each single call to to_bytes
in this case creates a string of length 1, with its characters arranged in big-endian order (which is trivial for length-1 strings), which represents the integer value byte
. You can also shorten the last two lines into a single one:
newFile.write(''.join([byte.to_bytes(1, byteorder='big') for byte in newFileBytes]))
You can use the following code example using Python 3 syntax:
from struct import pack
with open("foo.bin", "wb") as file:
file.write(pack("<IIIII", *bytearray([120, 3, 255, 0, 100])))
Here is shell one-liner:
python -c $'from struct import pack\nwith open("foo.bin", "wb") as file: file.write(pack("<IIIII", *bytearray([120, 3, 255, 0, 100])))'
To convert from integers < 256 to binary, use the chr
function. So you're looking at doing the following.
newFileBytes=[123,3,255,0,100]
newfile=open(path,'wb')
newfile.write((''.join(chr(i) for i in newFileBytes)).encode('charmap'))
Use pickle, like this: import pickle
Your code would look like this:
import pickle
mybytes = [120, 3, 255, 0, 100]
with open("bytesfile", "wb") as mypicklefile:
pickle.dump(mybytes, mypicklefile)
To read the data back, use the pickle.load method
Use struct.pack
to convert the integer values into binary bytes, then write the bytes. E.g.
newFile.write(struct.pack('5B', *newFileBytes))
However I would never give a binary file a .txt
extension.
The benefit of this method is that it works for other types as well, for example if any of the values were greater than 255 you could use '5i'
for the format instead to get full 32-bit integers.
Source: Stackoverflow.com