Python write to file

Question

I've got a little problem here. I'm converting binary to ascii, in order to compress data. All seems to work fine, but when I convert '11011011' to ascii and try to write it into file, I keep getting error

UnicodeEncodeError: 'charmap' codec can't encode character '\xdb' in position 0: character maps to

Here's my code:

 byte = ""
 handleR = open(self.getInput())
 handleW = open(self.getOutput(), 'w')
 file = handleR.readlines()
 for line in file:
 for a in range(0, len(line)):
 chunk = result[ord(line[a])]
 for b in chunk:
 if (len(byte) < 8):
 byte+=str(chunk[b])
 else:
 char = chr(eval('0b'+byte))
 print(byte, char)
 handleW.write(char)
 byte = ""
 handleR.close()
 handleW.close()

Any help appreciated,

Thank You

• David Z: When I read "binary to ASCII" I thought you were going the other way around, i.e. '\xdb' to '11011011' :-)

Answer 1

I think you want:

handleR = open(self.getInput(), 'rb')
handleW = open(self.getOutput(), 'wb')

That will ensure you're reading and writing byte streams. Also, you can parse binary strings without eval:

char = chr(int(byte, 2))

And of course, it would be faster to use bit manipulation. Instead of appending to a string, you can use << (left shift) and | (bitwise or).

EDIT: For the actual writing, you can use:

handleW.write(bytes([char]))

This creates and writes a bytes from a list consisting of a single number.

EDIT 2: Correction, it should be:

handleW.write(bytes([int(byte, 2)]))

There is no need to use chr.

• Mikk: Thank you for your answer, but how can I directly (with wb mode) write (str)"11011011" into file? No I get "TypeError: can't write str to binary stream"
• Mikk: Thank you so much. Final working and version is handleW.write(bytes(chr(int(byte, 2)), "utf-8"))
• Matthew Flaschen: @Mikk, my previous answer was partly wrong. It can just be handleW.write(bytes([int(byte, 2)])).