CODEWITHSUNDEEP
bashunixsedawk
Tony
Tony

Reputation: 2929

How to duplicate a matrix with awk?

I have the following 4 x 3 matrix with fields separated by a space.

Input

12.34 34.3 2.34
1.23 45.78 79.56
1.45 78.5 23.50
78.45 23.33 45.8

How to duplicate this matrix n times, in this case 2 times using awk or sed?

Desired output

12.34 34.3 2.34
1.23 45.78 79.56
1.45 78.5 23.50
78.45 23.33 45.8
12.34 34.3 2.34
1.23 45.78 79.56
1.45 78.5 23.50
78.45 23.33 45.8

Thanks for your help.

Tony

Upvotes: 1

Views: 203

Answers (6)

potong
potong

Reputation: 58430

This might work for you:

sed ':a;N;$!ba;:b;p;x;s/^/x/;/x\{2\}/d;x;bb' matrix.txt

Where /x\{2\}/ acts as a counter i.e. repeat 12 times change to /x\{12\}/

Upvotes: 1

kev
kev

Reputation: 161694

$ for i in {1..2}; do cat matrix.txt; done
$ sed -n 'H; ${g;s/.*/&&/p}' matrix.txt

To duplicate this matrix 10 times, just change 2(&&) to 10(&&&&&&&&&&)

Upvotes: 1

Jonathan Leffler
Jonathan Leffler

Reputation: 753990

The easiest way if the matrix is in a file matrix.txt is with cat:

cat matrix.txt matrix.txt

You can achieve essentially the same effect with sed:

sed 's/^//' matrix.txt matrix.txt

There aren't many other ways to do it easily with sed. You can also pull the same stunt with awk:

awk '{print $0}' matrix.txt matrix.txt

There's also a devious shorthand:

awk 1 matrix.txt matrix.txt

(Hint: the default action is print $0.)

Using awk, you can also arrange to read the file just once:

awk '{line[NR] = $0}
     END { for (j = 1; j <= 2; j++) { for (i = 1; i <= NR; i++) print line[i] } }' \
    matrix.txt

This is a space-time trade-off; awk is internalizing a copy of the file and regurgitating it twice;

Upvotes: 1

codaddict
codaddict

Reputation: 455122

To repeat it N times you can use:

perl -ne '{$x.=$_}END{print $x x N}' file

In your case replace N with 2.

Upvotes: 1

Fredrik Pihl
Fredrik Pihl

Reputation: 45662

I think you need to provide some more context; in what form is the original matrix and what would you like to do with it? Other than that, use:

$ cat matrix
12.34 34.3 2.34
1.23 45.78 79.56
1.45 78.5 23.50
78.45 23.33 45.8

$ cat matrix matrix 
12.34 34.3 2.34
1.23 45.78 79.56
1.45 78.5 23.50
78.45 23.33 45.8
12.34 34.3 2.34
1.23 45.78 79.56
1.45 78.5 23.50
78.45 23.33 45.8

Upvotes: 3

SiegeX
SiegeX

Reputation: 140367

awk '1' ./infile ./infile

sed -n 'p' ./infile ./infile

cat ./infile ./infile

Upvotes: 4

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