UNIX for Dummies Questions & Answers

Hello all, new to unix and have just found the forum.
I think I will be here quite often, and hope that in time i will be able to provide soem help, role on not being a newbie anymore


I have a question which iI am hoping someone could help me with.

If i have a file with lines in in thus ...

purple 2 color
purple 3 color
purple 4 color
purple 5 color
blue 1 color
blue 2 color
blue 3 color

how do i sort the list so only uniq instances of field 1 show with the highest value of field 2 ?

so in this case i would want to see ....

purple 5 color
blue 3 color

any help would be most welcome

cheers
grom

Hi.

You can use awk alone for this, or something like:

Code:

sort -nrk2,1 file1 | awk 'C != $1 { C = $1; print }'

works like a charm scottn, very much appreciated.
I have a lot to learn

Cheers

So do I, because actually, it doesnt!!

Add:

Code:

purple 27 color

and you'll see why!

Code:

sort -nrk2 file1 | awk '!C[$1] { C[$1]=1; print }'

See what you mean. I am glad your on the ball, I had only tried it on the example I posted, just tried again with your revised solution (and added numbers in there too) and all is ok.

could I trouble you and ask for a brief breakdown on how it works?

I have ordered the sed & awk book from amazon, hope i understand it when it comes LOL

cheers

sort is not a command I use often (evidently!).

My understanding was that by using -nrk2,1 the fields would be sorted (reverse) numerically by field 2, then by field 1 (presumably alphabetically - which was wrong).

If you try

Code:

sort -nrk2 file1

Then that's OK (numerically), but the rest (-nrk2,1) doesn't sort the first field after that as I thought.

Sort is a powerful command if you can master it - something I have neither the time nor inclination to do!

Given that the records are sorted reverse numerically in field 2 with "sort -nrk2"...

Code:

sort -nrk2 file1 | awk '!C[$1] { C[$1]=1; print }'

the awk says:
if I don't have a color (where $1 = purple, or whatever) in my array (C[purple]), then define something (anything) for purple (C[$1]=1) so that I do, and then print the line. If I do have something already defined, then do nothing (thus printing only the first line with each (sorted) color).

thanks, that has helped me make a bit of sense out of what, to me at the moment, seems like voodoo magic

I look forward to the point where I may be able to help someone on these forums, although I had better not hold my breath, i think i have a lot to learn.

once again, many thanks for your kind help, it's appreciated.

Cheers