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Full Discussion: Help with Alternative for NR==FNR
Top Forums Shell Programming and Scripting Help with Alternative for NR==FNR Post 302913374 by Corona688 on Friday 15th of August 2014 05:17:21 PM
Old 08-15-2014
NR==FNR doesn't look like the slow part, really. You could put a 'next' in that code block instead of the NR>FNR before the next code block, which may help by skipping that extra check. This doesn't actually look that slow though, honestly.

How large are your input files? How large are your lines? What do they look like? Are they sorted in any fashion?

The code NF?$0:a[x]"\n"; may be creating lots and lots of blank array indexes, a new one for each x not found. If your files are HUGE this may be a significant memory drain. Usually you'd do 'for X in a' before using it. What should it be doing/printing whenever x isn't found in the array?

You could try mawk if you have it, a bytecode-based awk implementation which sometimes has significant performance benefits.
Last edited by Corona688; 08-15-2014 at 06:23 PM..
 

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LEARN ABOUT OSX

ppmtosixel

ppmtosixel(1)						      General Commands Manual						     ppmtosixel(1)

NAME

       ppmtosixel - convert a portable pixmap into DEC sixel format

SYNOPSIS

       ppmtosixel [-raw] [-margin] [ppmfile]

DESCRIPTION

       Reads  a  portable  pixmap  as input.  Produces sixel commands (SIX) as output.	The output is formatted for color printing, e.g. for a DEC
       LJ250 color inkjet printer.

       If RGB values from the PPM file do not have maxval=100, the RGB values are rescaled.  A printer control header and a color assignment table
       begin the SIX file.  Image data is written in a compressed format by default.  A printer control footer ends the image file.

OPTIONS

       -raw   If  specified,  each  pixel  will  be explicitly described in the image file.  If -raw is not specified, output will default to com-
	      pressed format in which identical adjacent pixels are replaced by "repeat pixel" commands.  A raw file is often an order	of  magni-
	      tude larger than a compressed file and prints much slower.

       -margin
	      If  -margin  is not specified, the image will be start at the left margin (of the window, paper, or whatever).  If -margin is speci-
	      fied, a 1.5 inch left margin will offset the image.

PRINTING

       Generally, sixel files must reach the printer unfiltered.  Use the lpr -x option or cat filename > /dev/tty0?.

BUGS

       Upon rescaling, truncation of the least significant bits of RGB values may result in poor color conversion.  If the original PPM maxval was
       greater	than  100,  rescaling  also reduces the image depth.  While the actual RGB values from the ppm file are more or less retained, the
       color palette of the LJ250 may not match the colors on your screen.  This seems to be a printer limitation.

SEE ALSO

       ppm(5)

AUTHOR

       Copyright (C) 1991 by Rick Vinci.

								   26 April 1991						     ppmtosixel(1)
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