Code critique please

Jean-Michel Pichavant jeanmichel at sequans.com
Wed Apr 8 18:26:02 CEST 2015


----- Original Message -----
> From: "kai peters" <kai.peters at gmail.com>
> To: python-list at python.org
> Sent: Wednesday, 8 April, 2015 12:43:23 AM
> Subject: Code critique please
> 
> I just wrote this bit (coming from Pascal) and am wondering how
> seasoned Python programmers would have done the same? Anything
> terribly non-python?
> 
> As always, thanks for all input.
> 
> K
> 
> 
> 
> """
>  Creates a PNG image from EPD file
> """
> 
> import os, sys
> from PIL import Image, ImageFont, ImageDraw
> 
> #
> -----------------------------------------------------------------------------
> def RenderByte(draw, byte, x, y):
> 
>     blist = list(bin(byte).lstrip('0b')) # turn byte into list with 8
>     elements,
>     c = 0                                # each representing one bit
>     for bit in blist:
>         if bit:
>             draw.point((x + c, y), fcolor)
>             
>         c += 1
>     return
> 
> #

Apart from what has been already said, you could rewrite your function RenderByte this way (untested):

def render_byte(draw, byte, x, y):
  for point in [(x+c, y) for (c, bit) in enumerate(bin(byte)[2:]) if int(bit)]:
    draw.point(point, fcolor)


it involves important notions in the python language:
  - list comprehension, this is the  [...] part, where it combines filtering a list and applying a function to the values
  - slicing, bin(byte)[2:] returning the sequence stripped from its 2 first elements

Additional remarks : 
  - is fcolor defined ?
  - your test "if bit:" was probably wrong as it was testing either "0" or "1" which are both evaluated to True. In other words, bool("0") == True, bool(0) == False

Cheers,

JM


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