How do I get awk to print fields from the second row of a file? - awk

Question

I have a file that looks like this:
measured 10.8 0.0000 0.0000 0.0236 0.0304 0.0383 0.0433 0.0437 0.0442 0.0452
0.0455 0.0448 0.0440 0.0423 0.0386 0.0344 0.0274 0.0000 0.0000
I want gawk to print all the numbers in one long single column like this:
0.0000
0.0000
0.0236
0.0304
0.0383
0.0433
0.0437
0.0442
0.0452
0.0455
0.0448
0.0440
0.0423
0.0386
0.0344
0.0274
0.0000
0.0000
I run the command gawk '/measured/ { printf $3"\n" $4"\n" $5"\n" $6"\n" $7"\n" $8"\n" $9"\n" $10"\n" $11"\n" $12"\n" $13"\n" $14"\n" $15"\n" $16"\n" $17"\n" $18"\n" }' filename.txt
But I just get the first row of numbers:
0.0000
0.0000
0.0236
0.0304
0.0383
0.0433
0.0437
0.0442
0.0452
How do I get gawk to print the second row?

Answer 1

$ cat tst.awk
BEGIN { OFS = "\n" }
/measured/ { c=2; $1=$2=""; $0=$0 }
c && c-- { $1=$1; print }
$ awk -f tst.awk file
0.0000
0.0000
0.0236
0.0304
0.0383
0.0433
0.0437
0.0442
0.0452
0.0455
0.0448
0.0440
0.0423
0.0386
0.0344
0.0274
0.0000
0.0000

Answer 2

$ grep -A1 measured file | tr -s ' ' \\n | tail -n+4
0.0000
0.0000
0.0236
0.0304
0.0383
0.0433
0.0437
0.0442
0.0452
0.0455
0.0448
0.0440
0.0423
0.0386
0.0344
0.0274
0.0000
0.0000
with awk
$ awk -v OFS='\n' '/measured/ {p=1; for(i=3;i<=NF;i++) print $i; next}
p {$1=$1; print; exit}' file

Answer 3

If the number of fields is guaranteed to be as in the example, you can use the following command:
awk '{for(i=NF-8;i<=NF;i++){print $i}}' input.file

Answer 4

The GNU implementation of Awk allows an arbitrary regular expression as the RS record separator If the keyword measured occurs before each batch of numbers, we can use that keyword as the separator:
$ gawk 'BEGIN { RS = "measured" } { for (i = 1; i <= NF ; i++) print "field " i " = " $i }'
measured 10.8 0.0000 0.0000 0.0236 0.0304 0.0383 0.0433 0.0437 0.0442 0.0452
0.0455 0.0448 0.0440 0.0423 0.0386 0.0344 0.0274 0.0000 0.000
field 1 = 10.8
field 2 = 0.0000
field 3 = 0.0000
field 4 = 0.0236
field 5 = 0.0304
field 6 = 0.0383
field 7 = 0.0433
field 8 = 0.0437
field 9 = 0.0442
field 10 = 0.0452
field 11 = 0.0455
field 12 = 0.0448
field 13 = 0.0440
field 14 = 0.0423
field 15 = 0.0386
field 16 = 0.0344
field 17 = 0.0274
field 18 = 0.0000
field 19 = 0.000
As you can see, all the fields between the measured record separators are parsed out regardless of line breaks. Fields are separated on any mixture of spaces, tabs and newlines.
Note that because measured appears first, we get an empty record. The output you see above is, effectively, from the second record. The first record is the whitespcae before measured, which contains no fields.
In other words, he record separator is really expected to be a terminator, except that it can be missing after the last record.