UNIX for Dummies Questions & Answers

Dear all,

I have a file like below. I want to replace all the '.' in the 3rd column with 'NA'. I don't know how to do that. Anyone has an iead? Thanks a lot!

8 70003200 21.6206
9 70005700 17.5064
10 70002200 .
11 70005100 19.1001
17 70008000 16.1970
32 70012400 26.3465
33 70014900 19.2607
34 70015500 19.1406
35 70007800 18.0802
36 70015300 .
37 70008600 16.1844

Code:

sed 's/\./NA/g' infile

Or ... if you never have more than 1 dot per line you can go with

Code:

sed 's/\./NA/' infile

if you wan only replace the single dot , not those like 12.65849

then

Code:

sed 's/\.$/NA/' infile

If it is literally a replace of the full stop character with NA, then you could try:-

Code:

echo ":%s /\./NA/\nwq"|vi filename

It may not work if:-
It is likely that sed could do it better, but I'm not a good writer. If you don't mind it being slow, you could also try (in korn shell):-

Code:

cat filename||tr "." " "|while read col1 col col3 col4
do
   echo $col1 $col2 ${col3}NA$col4
done>new_filename

Be aware that you cannout write to the file you are reading from. This could be rather slow if you are reading in a large file.



I hope that this helps, but like I said, a sed would probably be better.




Robin
Liverpool/Blackburn
UK

Thanks a lot! it works. one more question: why do me need '\.' but not simply '.'

Thanks

because dot has a special meaning when interpreted as a regular expression it means 'any single character' so it needs to be "escaped" using the backslash

Code:

printf ",s/\./NA/\nw\nq\n" | ed -s infile

thanks! One more question: if I want only replace the dot in a certain column, saying 3rd column, how to do that? sorry, I am new to unix. Thanks again!

Using awk
If you just want to replace the . in the 3rd column

Code:

awk '{if($3==".") print $1" "$2" NA";else print}' infile