Selecting Records from Data 1

[thunderkid]

I am a novice at awk. I have searched database for script that I might modify, but have not had any success. I am trying to selectively picked records from data file. Here is a sample of input file:

123 <time1_data> aaaa
123 <time2_data> aaaa
234 <time3_data> aaaa
234 <time4_data> aaaa
234 <time5_data> aaaa
345 <time6_data> aaaa
345 <time7_data> aaaa
345 <time8_data> aaaa
345 <time9_data> aaaa
.
.
.

desired output:

The first extraction should pick the first record when col one fields are the same:
123 <time1_data> aaaa
234 <time3_data> aaaa
345 <time6_data> aaaa


In another extraction I need to pick the second record when col one fields are the same:
123 <time2_data> aaaa
234 <time4_data> aaaa
345 <time7_data> aaaa

These are two separate extractions. Nice to have one script which can be modified to do second extraction.

thanks
thunderkid

 

[PHV]

Try something like this:
awk -v ind=1or2 '++a[$1]==ind' </path/to/file

Hope This Help, PH.
Want to get great answers to your Tek-Tips questions? Have a look at FAQ219-2884

 

[futurelet]

Assuming you want to print only when two or more records in sequence have field 1 the same:
[tt]
$1 && $1==prev { count++
if (1==count)
print show2nd ? $0 : prev_rec }
$1!=prev { count=0 }
{prev=$1; prev_rec=$0}
[/tt]
To make it show 2nd line, use [tt]awk -v show2nd=1[/tt].

If you have nawk, use it instead of awk because
on some systems awk is very old and lacks many useful features.

Let me know whether or not this helps.

 

[thunderkid]

PHV
Your solutions worked great! You guys really make this forum such a valuable resource for sharing knowledge and spreading the usefulness of "awk". Thanks to you and others that make it possible.
thunderkid

Have a star!

 

[thunderkid]

Feedback for futurelet. As you indicated in your response, your solution works for 2 or more. I really needed it to handle all cases.

I was not able to get second script (writes 2nd record) to work:
awk -v show2nd=1

Thanks.
thunderkid