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awk to count pattern matches

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# 8  
Old 12-12-2008
Quote:
Originally Posted by vgersh99
that doesn't work for multiple (and sequential) occurrences of a pattern on the same line/record:
Code:
echo '1,1,2,5,5,5,6,5,4,5,7'| nawk '{while (sub(/,5,/,",")) t++}END{print t}'


That's only good for one line, and there's no need for a loop:

Code:
 awk '{ total += gsub(/,5,/,"") } END { print total }'

# 9  
Old 12-12-2008
Hi.

Another method:
Code:
#!/bin/bash -

# @(#) s1       Demonstrate count of strings with awk, field separator.

echo
echo "(Versions displayed with local utility \"version\")"
version >/dev/null 2>&1 && version "=o" $(_eat $0 $1) awk
set -o nounset

FILE=${1-data1}

echo
echo " Data file $FILE:"
cat $FILE

echo
echo " Results:"
awk -F",5," '
BEGIN   { t = 0 }
        { t += NF }
END     {print t}
' $FILE

Producing:
Code:
% ./s1

(Versions displayed with local utility "version")
Linux 2.6.11-x1
GNU bash 2.05b.0
GNU Awk 3.1.4

 Data file data1:
1,1,2,5,5,5,6,5,4,5,7

 Results:
5

cheers, drl
# 10  
Old 12-13-2008
Quote:
Originally Posted by vgersh99
that doesn't work for multiple (and sequential) occurrences of a pattern on the same line/record:
Code:
echo '1,1,2,5,5,5,6,5,4,5,7'| nawk '{while (sub(/,5,/,",")) t++}END{print t}'

[...]
Quote:
Originally Posted by cfajohnson
That's only good for one line
[...]
For one line? Why?
# 11  
Old 12-13-2008
Quote:
Originally Posted by radoulov
For one line? Why?

Sorry, I don't know what I was thinking. (But gsub() does avoid the while loop.)
# 12  
Old 12-13-2008
Quote:
Originally Posted by cfajohnson

Sorry, I don't know what I was thinking. (But gsub() does avoid the while loop.)
I thought the same, but:
Code:
$ echo '1,1,2,5,5,5,6,5,4,5,7' | awk '{ total += gsub(/,5,/,"") } END { print total }'
4

# 13  
Old 12-13-2008
Hi.

In many RE implementations, one cannot have over-lapping matched sections of strings, so the result noted makes sense in that context.

I was surprised that my solution on post # 9 worked, since I would have expected the same behavior with a field split based on a regular expression as separator.

Perhaps the explanation is that for the gsub, part of the string is now replaced by the empty string which makes the next ",5," in the original no longer present, but rather "5,", causing the next one to be considered. For the field split, there is no replacement ... cheers, drl
# 14  
Old 12-13-2008
thats very useful guys. thanks guys.

i was using a separate while loop anyway to read in line by line from a file and then use pattern matching to extract and count ,5,

i was getting confused with awk.. when do you use something like {count++;}? i mean count++ with a semicolon and when do u use it without a semicolon?
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