Remove every fourth line from CSV file?

briana.paige · 08-12-2009, 09:40 AM

Hi,

I have a large csv file which has data for every 15 minutes and I need only the hourly data. I would like to keep the first line, delete the next three lines, keep the fourth etc...

Sample of the orig data:

Code:

01/01/2009	0:00:57	sleep	84	8.4	-13.11
01/01/2009	0:16:12	sleep	84	8.4	-13.11
01/01/2009	0:31:27	sleep	84	8.4	-13.11
01/01/2009	0:46:42	sleep	84	8.4	-13.11
01/01/2009	1:01:57	sleep	84	8.4	-13.11
01/01/2009	1:17:12	sleep	84	8.4	-13.11
01/01/2009	1:32:27	sleep	84	8.4	-13.11
01/01/2009	1:47:42	sleep	81	8.1	-13.28
01/01/2009	2:02:57	sleep	81	8.1	-13.28

Desired output from above data:

Code:

01/01/2009	0:00:57	sleep	84	8.4	-13.11
01/01/2009	1:01:57	sleep	84	8.4	-13.11
01/01/2009	2:02:57	sleep	81	8.1	-13.28

A simple awk or bash command would suffice as I only need to perform this operation on 1 or 2 files.

Any help is appreciated!
Thanks.

pwc101 · 08-12-2009, 09:49 AM

Code:

sed -n '1~4p' input

Prints every 4th line. Add -i to make the changes permanent.

See http://www-h.eng.cam.ac.uk/help/tpl/unix/sed.html

briana.paige · 08-12-2009, 10:06 AM

Works like a charm, exactly what I needed! Thank-you so much!

pwc101 · 08-12-2009, 10:07 AM

No problem

If you want to change the starting line, change the 1 to the line you want to start from. Likewise change 4 to 8 if you want it every 2 hours instead.

I'm sure there is an awk solution too, but if this works, so much the better. It's not exactly the longest command ever, either