choose random text between constant string.. using awk?

Shell Programming and Scripting
1

Hallo
I have maybe a little bit advanced request....
I need to choose one random part betwen %....

so i have this..

%
text1 text1 text1
text1 text1 text1
text1 text1 text1
%
text2 text2
text2 text2 text2
%
text3 text3 text3
tetx3
%

this choose text between %

awk ' /%/ {flag=1;next} /%/{flag=0} flag { print }' file

so i get

text1 text1 text1
text1 text1 text1
text1 text1 text1
text2 text2
text2 text2 text2
text3 text3 text3
tetx3

I NEED JUST ONE PART

text1 text1 text1
 text1 text1 text1
 text1 text1 text1

or

text2 text2
 text2 text2 text2

or

text3 text3 text3
 tetx3

Any help would be appreciate....

2

Your solution is equivalent to:

awk '/%/{next}{print}' infile

This should print only the first segment:

awk '/%/{p++;next}p==1{print}' infile

This the second:

awk '/%/{p++;next}p==2{print}' infile

etcetera

3

Thank you very much Scrutinizer.... this helped me a lot...

awk '/%/{p++;next}p==1{print}' infile
4

try the next code uses rand function

awk 'BEGIN{ RS="%"  ;srand() } { line[NR] = $0 } END{ print line[randint(NR)] } function randint(n) {return int(n * rand()) + 1}' infile

Or

awk 'BEGIN{ RS="%\n"  ;srand() } { line[NR] = $0 } END{ print line[int((NR* rand()) + 1)]}'  infile
5

Very nice ironmask2004 it is great too ....

I have just finished it with the previous solution

vtip=$RANDOM
let "vtip=1+(vtip%2125)"
awk -v cislo=$vtip '/%/{p++;next}p==cislo' vtipy.txt
6

but you need to know how muche recoreds you have insaide the fill to generate a random number betwwen 1 and NUM Of Rec !!!

7

yes good question i have used

grep -c "^[%]" vtipy.txt

and the number was 2126

vtip=$RANDOM
let "vtip=1+(vtip%2125)"   #thats why here is 2125 it is modulo
awk -v cislo=$vtip '/%/{p++;next}p==cislo' vtipy.txt
8

:b:

  1. % ↩︎

9

Hi.

If one is willing to devote the time and effort, the reservoir sampling method allows one to extract a random sample in a single pass through a file. A brief explanation along with a python and perl code can be found at Program-o-Babble: Reservoir Sampling Algorithm in Python and Perl among many other places.

Best wishes ... cheers, drl