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To: python-list@python.org
From: Dennis Lee Bieber <wlfraed@ix.netcom.com>
Subject: Re: How does .rjust() work and why it places characters relative to previous one, not to first character - placed most to left - or to left side of screen?
Date: Sun, 19 Aug 2012 14:56:39 -0400
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On Sun, 19 Aug 2012 09:25:03 -0700 (PDT), crispy <ryniek90@gmail.com>
declaimed the following in gmane.comp.python.general:

	<snip>

> So I have guessed, that characters processed by .rjust() function, are placed in output, relative to previous ones - NOT to first, most to left placed, character.
> Why it works like that? What builtn-in function can format output, to make every character be placed as i need - relative to the first character, placed most to left side of screen.
>

	str.rjust(x) will right justify "str" in a field of "x" width. This
is done by adding enough spaces to the left to make the length of the
result string (spaces + "str") equal to the specified width. The method
works on strings, not on output lines.

	Make sure your display is using fixed width fonts, not variable.

>>> strs = ["1", "to", "two", "long term", "short"]
>>> for s in strs:
... 	print s.rjust(8), s.rjust(10), s.ljust(8), s.ljust(10),
s.center(10)
... 	
       1          1 1        1              1     
      to         to to       to             to    
     two        two two      two           two    
long term  long term long term long term  long term 
   short      short short    short        short   

(Note that xjust doesn't trim a long string, which is why the line of
"long term" does not align)

>>> for s in strs:
... 	print s[:8].rjust(8), s.rjust(10), s[:8].ljust(8), s.ljust(10),
s.center(10)
... 	
       1          1 1        1              1     
      to         to to       to             to    
     two        two two      two           two    
long ter  long term long ter long term  long term 
   short      short short    short        short  

	In the above samples, I have specified an output line containing 5
"fields" of sizes 8, 10, 8, 10, 10, and using right, right, left, left,
centered justification. 


	If you need to layout a whole line, where some positions are being
set based on indexes, you need to do that as one array, not a collection
of substrings.

>>> match = [2, 7, 9, 13, 14, 24, 4]
	dummy data, note that order doesn't matter

>>> buffer = [" "] * max(match)
	build empty array sized to needed output

>>> print repr(buffer)
[' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', '
', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ']
>>> for m in match:
... 	buffer[m - 1] = "|"
... 	
	replace space with pipe for each position in match (match is
presumed to count from 1, but Python indexes from 0)

>>> print repr(buffer)
[' ', '|', ' ', '|', ' ', ' ', '|', ' ', '|', ' ', ' ', ' ', '|', '|', '
', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', '|']
>>> output = "".join(buffer)
	join the position contents together to make the final output line

>>> print repr(output)
' | |  | |   ||         |'
-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
        wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/