Split File Based on Line Number Pattern

shankster · #1 (**permalink**) 09-30-2008

Hello all.

Sorry, I know this question is similar to many others, but I just can seem to put together exactly what I need.

My file is tab delimitted and contains approximately 1 million rows. I would like to send lines 1,4,& 7 to a file. Lines 2, 5, & 8 to a second file. Lines 3, 6, & 9 to a third file, and then line 10 to a fourth file. I then want to repeat this condition using the same scenario, and the same four files above. Any thoughts on the best approach?

joeyg · #2 (**permalink**) 09-30-2008

But, I will need some awk help (or to think a little clearer after eating lunch)

Code:

> cat big_file4
a stuff to 1 file
b stuff to 2 file
c stuff to 3 file
a stuff to 1 file
b stuff to 2 file
c stuff to 3 file
a stuff to 1 file
b stuff to 2 file
c stuff to 3 file
d stuff to 4 file
a stuff to 1 file
b stuff to 2 file
c stuff to 3 file
a stuff to 1 file
b stuff to 2 file
c stuff to 3 file
a stuff to 1 file
b stuff to 2 file
c stuff to 3 file
d stuff to 4 file

What I initially wrote does not capture the file line of text - and where I think I need some HELP!

Code:

> cat -n big_file4 | awk '{printf "%1s %-15s \n", substr($1,length($1),1), $2}'
1 a               
2 b               
3 c               
4 a               
5 b               
6 c               
7 a               
8 b               
9 c               
0 d               
1 a               
2 b               
3 c               
4 a               
5 b               
6 c               
7 a               
8 b               
9 c               
0 d

Because from here, my theory is that

Code:

grep "^[147] " <infile >outfile_a
grep "^[258] " <infile >outfile_b
grep "^[369] " <infile >outfile_c
grep "^[0] " <infile >outfile_d

May need to cut before writing to each output.

era · #3 (**permalink**) 09-30-2008

Perl or Python looping over a set of file handles would seem like the most i efficient approach. For a more pedestrian solution, an awk script run four times with different parameters might be acceptable even if the file is big.

Does file four only contain every tenth line, and then 11, 14, and 17 go to the first file again?

Code:

perl -MIO::File -ne 'BEGIN { map { $file[$_] = IO::File->new(">file$_") || die $!} 0..3; 
  @m = (0, 1, 2, 0, 1, 2, 0, 1, 2, 3);
}
$file[$m[$. % 9]]->print || die $!'

csplit has some fairly versatile options, you might be able to pull this off simply with a suitable csplit pattern as well.

shankster · #4 (**permalink**) 09-30-2008

Yes, 11,14, and 17 would then go to the first file again.

I am trying to use KSH to complete this task. Below is what I have so far, but the count variable does not appear to be resetting to 1 after it reaches 11. Also, I am getting output similar to:

File_split_DC.sh[42]: 2: not found.
File_split_DC.sh[42]: 3: not found.
File_split_DC.sh[42]: 4: not found.

The name of my script is "File_split_DC.sh"

#!/usr/bin/ksh

count=1

while read line
do

case $count in
1)
echo "$line" >> RT1.txt
;;
2)
echo "$line" >> RT2.txt
;;
3)
echo "$line" >> RT3.txt
;;
4)
echo "$line" >> RT1.txt
;;
5)
echo "$line" >> RT2.txt
;;
6)
echo "$line" >> RT3.txt
;;
7)
echo "$line" >> RT1.txt
;;
8)
echo "$line" >> RT2.txt
;;
9)
echo "$line" >> RT3.txt
;;
10)
echo "$line" >> RT4.txt
;;
esac
(( count+=1 ))

if $count -gt 10; then
count=1

fi
done < My_Test.txt

exit 0

era · #5 (**permalink**) 09-30-2008

You want

Code:

if [ $count -gt 10 ]; then

It would be more efficient to open four file descriptors and then just print to those descriptors; this approximates the Perl approach I suggested above.

Code:

exec 1>rt1.txt 2>rt2.txt 3>rt3.txt 4>rt4.txt
count=1
while read line; do
  case $count in
    1|4|7) print "$line" >&1;;
    2|5|8) print "$line" >&2;;
    3|6|9) print "$line" >&3;;
    10) print "$line" >&4; count=0;;
  esac
  count=`expr $count + 1`
done <My_Test.txt

Note the use of print rather than echo -- this is ksh-specific, but other than that, this script should be portable.

joeyg · #6 (**permalink**) 09-30-2008

Code:

> cat -n big_file4 | awk '{printf "%1s %-100s \n", substr($1,length($1),1), $0}' | cut -c1,10- | grep "^[147]" | cut -c2- >filea
> cat -n big_file4 | awk '{printf "%1s %-100s \n", substr($1,length($1),1), $0}' | cut -c1,10- | grep "^[258]" | cut -c2- >fileb
> cat -n big_file4 | awk '{printf "%1s %-100s \n", substr($1,length($1),1), $0}' | cut -c1,10- | grep "^[369]" | cut -c2- >filec
> cat -n big_file4 | awk '{printf "%1s %-100s \n", substr($1,length($1),1), $0}' | cut -c1,10- | grep "^[0]" | cut -c2- >filed

Code:

> cat big_file4
a stuff to 1 file
b stuff to 2 file
c stuff to 3 file
a stuff to 1 file
b stuff to 2 file
c stuff to 3 file
a stuff to 1 file
b stuff to 2 file
c stuff to 3 file
d stuff to 4 file
a stuff to 1 file
b stuff to 2 file
c stuff to 3 file
a stuff to 1 file
b stuff to 2 file
c stuff to 3 file
a stuff to 1 file
b stuff to 2 file
c stuff to 3 file
d stuff to 4 file

and now the four separated files

Code:

> cat filea
a stuff to 1 file                                                                             
a stuff to 1 file                                                                             
a stuff to 1 file                                                                             
a stuff to 1 file                                                                             
a stuff to 1 file                                                                             
a stuff to 1 file                                                                             
> cat fileb
b stuff to 2 file                                                                             
b stuff to 2 file                                                                             
b stuff to 2 file                                                                             
b stuff to 2 file                                                                             
b stuff to 2 file                                                                             
b stuff to 2 file                                                                             
> cat filec
c stuff to 3 file                                                                             
c stuff to 3 file                                                                             
c stuff to 3 file                                                                             
c stuff to 3 file                                                                             
c stuff to 3 file                                                                             
c stuff to 3 file                                                                             
> cat filed
d stuff to 4 file                                                                             
d stuff to 4 file                                                                             
>

shankster · #7 (**permalink**) 09-30-2008

Thanks to both of you for your input. I really don't know what I'm doing when it comes to UNIX, so I just try to piece tidbits together. I ended up using ERA's approach in the second posting. It was similar to what I had already put together, and made sense. JOEYG, I'm sure your appraoch would work as well, and I appreciate your input.

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