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Full Discussion: Use awk to read multiple files twice
Top Forums UNIX for Advanced & Expert Users Use awk to read multiple files twice Post 302606645 by Scrutinizer on Monday 12th of March 2012 10:12:30 AM
Old 03-12-2012
You could feed the files twice, like so:
Code:
awk -f  test.awk test*.txt test*.txt

Then you can test if the second round of files is coming like so for example:
Code:
FILENAME==ARGV[1] && NR>FNR{secondround=1}
secondround{print "Making SD calculations"}

ARGV[1] contains the first filename. If the current filename FILENAME equals ARGV[1] for the second time, you will have processed all the files once...
This way you would need to store a lot less information

------------
Or you can do it like this, setting the variable half-way. Then you do not have to test inside, which might be a speed advantage:
Code:
awk -f  test.awk test*.txt secondround=1 test*.txt

and inside the awk script:
Code:
secondround{print "Making SD calculations"}

Last edited by Scrutinizer; 03-12-2012 at 11:55 AM.. Reason: changed NR>1 to NR>FNR. Thanks ctsgnb
These 2 Users Gave Thanks to Scrutinizer For This Post:
ctsgnb scandy
 

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LEARN ABOUT SUNOS

mlib_imagestddev

mlib_ImageStdDev(3MLIB) 				    mediaLib Library Functions					   mlib_ImageStdDev(3MLIB)

NAME

       mlib_ImageStdDev - image standard deviation

SYNOPSIS

       cc [ flag... ] file... -lmlib [ library... ]
       #include <mlib.h>

       mlib_status mlib_ImageStdDev(mlib_d64 *sdev, const mlib_image *img, const mlib_d64 *mean);

DESCRIPTION

       The mlib_ImageStdDev() function computes the standard deviation for each channel in the source image.

       It uses the following equation:

		     1	   w-1 h-1
       sdev[i] = { ----- * SUM SUM (img[x][y][i] - mean[i])**2 }**0.5
		    w*h    x=0 y=0

       where, in the case of mean == NULL,

		   1	 w-1 h-1
       mean[i] = ----- * SUM SUM img[x][y][i]
		  w*h	 x=0 y=0

PARAMETERS

       The function takes the following arguments:

       sdev	       Pointer	to standard deviation array, whose size is the number of channels in the source image.	sdev[i] contains the stan-
		       dard deviation of channel i.

       img	       Pointer to input image.

       mean	       Pointer to pre-computed mean array for each channel.  (If NULL, it will be computed.)  mean[i] contains the mean of channel
		       i.

RETURN VALUES

       The function returns MLIB_SUCCESS if successful. Otherwise it returns MLIB_FAILURE.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Evolving			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       mlib_ImageMean(3MLIB), mlib_ImageMean_Fp(3MLIB), mlib_ImageStdDev_Fp(3MLIB), attributes(5)

SunOS 5.10							    10 Nov 2004 					   mlib_ImageStdDev(3MLIB)
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