Is there a simple way to, in Python, read a file's hexadecimal data into a list, say hex?
So hex would be this:
hex = ['AA','CD','FF','0F']
I don't want to have to read into a string, then split. This is memory intensive for large files.
Is there a simple way to, in Python, read a file's hexadecimal data into a list, say hex?
So hex would be this:
hex = ['AA','CD','FF','0F']
I don't want to have to read into a string, then split. This is memory intensive for large files.
s = "Hello"
hex_list = ["{:02x}".format(ord(c)) for c in s]
Output
['48', '65', '6c', '6c', '6f']
Just change s to open(filename).read() and you should be good.
with open('/path/to/some/file', 'r') as fp:
hex_list = ["{:02x}".format(ord(c)) for c in fp.read()]
Or, if you do not want to keep the whole list in memory at once for large files.
hex_list = ("{:02x}".format(ord(c)) for c in fp.read())
and to get the values, keep calling
next(hex_list)
to get all the remaining values from the generator
list(hex_list)
hex_list a generator if you are that concerned about it[ ] to ( ). It is currently called list-comprehension. Change to parenthesis and you have a generator-comprehension.next calls inside a try..except StopIteration.fp.read() reading the whole input file in memory anyway? Also: if the file is a pure sequence of binary data (I've just tried with the given numbers), you might get the error UnicodeDecodeError: 'utf-8' codec can't decode byte 0xaa in position 0: invalid start byte, since you open the file in text mode. I am using python 3Using Python 3, let's assume the input file contains the sample bytes you show. For example, we can create it like this
>>> inp = bytes((170,12*16+13,255,15)) # i.e. b'\xaa\xcd\xff\x0f'
>>> with open(filename,'wb') as f:
... f.write(inp)
Now, given we want the hex representation of each byte in the input file, it would be nice to open the file in binary mode, without trying to interpret its contents as characters/strings (or we might trip on the error UnicodeDecodeError: 'utf-8' codec can't decode byte 0xaa in position 0: invalid start byte)
>>> with open(filename,'rb') as f:
... buff = f.read() # it reads the whole file into memory
...
>>> buff
b'\xaa\xcd\xff\x0f'
>>> out_hex = ['{:02X}'.format(b) for b in buff]
>>> out_hex
['AA', 'CD', 'FF', '0F']
If the file is large, we might want to read one byte at a time or in chunks. For that purpose I recommend to read this Q&A
Be aware that for viewing hexadecimal dumps of files, there are utilities available on most operating systems. If all you want to do is hex dump the file, consider one of these programs:
od (octal dump, which has a -x or -t x option)hexdumpxd utility available under windows