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Full Discussion: Better way to match a list in awk
Top Forums Shell Programming and Scripting Better way to match a list in awk Post 302909722 by treesloth on Friday 18th of July 2014 03:01:19 PM
Old 07-18-2014
Better way to match a list in awk
Suppose I have a list of strings in a file called stringlist...

string1
string2
...
stringn

Suppose also that I have another file, or stdin, or whatever, and I want to use awk to see if some field in each record matches any string in stringlist. What I've been doing is using each string on the list as an index of an array isOnList, and the value of the array element is a unique string, like YUPPERS. This is in my BEGIN block:

Code:
while ("cat file_containing_strings" | getline)
     {
     isOnList[$1] = "YUPPERS"
     }

Suppose I'm interested in finding out whether, say, field 7 matches anything on the list. I have the list read into the array, so to do the testing in the body of my script, I simply do something like this:

Code:
isOnList[$7] == "YUPPERS"   {
     do some stuff...
     }

It works, and it seems reasonably efficient, but I wonder if there's a faster, less expensive way to do this. Looping through the array on each line can be pretty costly, I imagine. How would you all go about solving this sort of problem? Thanks.
 

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LEARN ABOUT OPENSOLARIS

igawk

IGAWK(1)							 Utility Commands							  IGAWK(1)

NAME

       igawk - gawk with include files

SYNOPSIS

       igawk [ all gawk options ] -f program-file [ -- ] file ...
       igawk [ all gawk options ] [ -- ] program-text file ...

DESCRIPTION

       Igawk is a simple shell script that adds the ability to have ``include files'' to gawk(1).

       AWK programs for igawk are the same as for gawk, except that, in addition, you may have lines like

	      @include getopt.awk

       in your program to include the file getopt.awk from either the current directory or one of the other directories in the search path.

OPTIONS

       See gawk(1) for a full description of the AWK language and the options that gawk supports.

EXAMPLES

       cat << EOF > test.awk
       @include getopt.awk

       BEGIN {
	    while (getopt(ARGC, ARGV, "am:q") != -1)
		 ...
       }
       EOF

       igawk -f test.awk

SEE ALSO

       gawk(1)

       Effective AWK Programming, Edition 1.0, published by the Free Software Foundation, 1995.

AUTHOR

       Arnold Robbins (arnold@skeeve.com).

ATTRIBUTES

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

       +--------------------+-----------------+
       |  ATTRIBUTE TYPE    | ATTRIBUTE VALUE |
       +--------------------+-----------------+
       |Availability	    | SUNWgawk	      |
       +--------------------+-----------------+
       |Interface Stability | Volatile	      |
       +--------------------+-----------------+
NOTES

       Source for gawk is available on http://opensolaris.org.

Free Software Foundation					    Nov 3 1999								  IGAWK(1)
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