Meaning of NF{ a[$1]=a[$1]" "$2 ; next }? Post: 302389754

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Top Forums Shell Programming and Scripting Meaning of NF{ a[$1]=a[$1]" "$2 ; next }? Post 302389754 by Scott on Monday 25th of January 2010 06:25:06 PM

01-25-2010

Administrator Emeritus

Hi.

It's part of an awk script.

NF{...} means if there are more than zero fields in the current record (i.e. not a blank line) perform the action between { and }

An awk script is made up of patterns (conditions, really) and actions

PATTERN { ACTION }

If PATTERN evaluates to true, then ACTION is performed.

[NF is an awk variable giving the number of fields in the current record. If it's non-zero, ACTION is performed.]

{ a[$1]=a[$1]" " $2; next } means append the value of field two ($2) to an array (a) indexed by the value of field one ($1).

The END section is performed after all input files are processed.

for(i in a) means assign to i, in turn, each element of a
and print the index value i, followed by the value referenced by that index (a[i]).

The two lines you posted say: add field two to an array called a, indexed by distinct values of field one.

HTH Smilie

Scott

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graphics::primitive::insets

Graphics::Primitive::Insets(3pm)			User Contributed Perl Documentation			  Graphics::Primitive::Insets(3pm)

NAME

       Graphics::Primitive::Insets - Space between things

DESCRIPTION

       Graphics::Primitive::Insets represents the amount of space that surrounds something.  This object can be used to represent either padding
       or margins (in the CSS sense, one being inside the bounding box, the other being outside)

SYNOPSIS

	 use Graphics::Primitive::Insets;

	 my $insets = Graphics::Primitive::Insets->new({
	   top	   => 5,
	   bottom  => 5,
	   left    => 5,
	   right   => 5
	 });

METHODS

   Constructor
       new Creates a new Graphics::Primitive::Insets.

   Instance Methods
       as_array
	   Return these insets as an array in the form of top, right, bottom and left.

       bottom
	   Set/Get the inset from the bottom.

       equal_to
	   Determine if these Insets are equal to another.

       left
	   Set/Get the inset from the left.

       right
	   Set/Get the inset from the right.

       top Set/Get the inset from the top.

       zero
	   Sets all the insets (top, left, bottom, right) to 0.

AUTHOR

       Cory Watson, "<gphat@cpan.org>"

SEE ALSO

       perl(1)

COPYRIGHT &; LICENSE
       Copyright 2008-2010 by Cory G Watson.

       This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

perl v5.12.3							    2010-08-21					  Graphics::Primitive::Insets(3pm)