Column manipulation using AWK

I have a file with more than 200 columns. As for example purpose, I am here using a file with less number of columns(9). Below is the input file (a few lines)

chr10 181243 225933 1 1 1 10 0 36
chr10 181500 225933 1 1 1 106 0 35
chr10 226069 255828 1 1 1 57 0 37
chr10 243946 255828 1 1 1 4 0 27
chr10 255989 267134 1 1 1 87 0 32
chr10 255989 282777 1 1 1 61 0 34
chr10 267297 282777 1 1 1 61 0 37
chr10 282856 283524 1 1 1 92 0 35
chr10 282856 285377 1 1 1 1 0 15
chr10 283618 285377 1 1 1 72 0 33


I want to rearrange the file such that my last column (here the 9th column) is the 4th column in the output file and then print everything else. So the output I am looking for is

chr10 181243 225933 36 1 1 1 10 0
chr10 181500 225933 35 1 1 1 106 0
chr10 226069 255828 37 1 1 1 57 0
chr10 243946 255828 27 1 1 1 4 0
chr10 255989 267134 32 1 1 1 87 0
chr10 255989 282777 34 1 1 1 61 0
chr10 267297 282777 37 1 1 1 61 0
chr10 282856 283524 35 1 1 1 92 0
chr10 282856 285377 15 1 1 1 1 0
chr10 283618 285377 33 1 1 1 72 0


On a file with fewer number of columns, I can use something like this to achieve the above output:

awk -v OFS="t" 'print $1,$2,$3,$9,$4,$5,$6,$7,$8'


If now I have a file with a large number of columns, how can I place the last column of the file as the 4th column and rest I print as it is?

2 Answers
2

Perl is very concise for this: split each line into words, pop off the last word and insert it at
index 3 (0-based)

$ perl -lane 'splice @F, 3, 0, pop(@F); print "@F"' file | column -t
chr10 181243 225933 36 1 1 1 10 0
chr10 181500 225933 35 1 1 1 106 0
...


To replace the fourth field with the last field:

awk -v OFS="t" ' $4 = $NF; $NF=""; print


To insert the last field before the fourth field, we have to get a little creative:

awk -v OFS="t" 'temp=$NF; for( i=NF;i>4;i-- ) $i=$(i-1); $4=temp ; print'


This will preserve the final field, zip through all the fields and move each one backward to the fourth forward one, and then put the desired fourth field into place:

$ echo 1..10 | awk -v OFS="t" 'temp=$NF; for( i=NF;i>4;i-- ) $i=$(i-1); $4=temp ; print'
1 2 3 10 4 5 6 7 8 9


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