Multiply all values in txt file in bash-CodePudding

I have a file that I need to multiply each number with -1. I have tried some commands but the result I get every time is only the first column multiplied with -1. Please help!

The file is as follows:

-1 2 3 -4 5 -6
7 -8 9 10 12 0

The expected output would be

1 -2 -3 4 -5 6
-7 8 -9 -10 -12 0

Commands I have tried are:

awk '{print $0*-1}' file
sed 's/$/ -1*p /' file  | bc (syntax error)
sed 's/$/ * -1 /' file  | bc (syntax error)
numfmt --from-unit=-1 < file (error: numfmt: invalid unit size: ‘-1’)

CodePudding user response：

With bash and an array:

while read -r -a arr; do
  declare -ia 'arr_multiplied=( "${arr[@]/%/*-1}" )';
  echo "${arr_multiplied[*]}";
done < file

Output:

1 -2 -3 4 -5 6
-7 8 -9 -10 -12 0

Idea: https://stackoverflow.com/a/46242196/3776858

CodePudding user response：

One awk approach:

$ awk '{for (i=1;i<=NF;i  ) $i=$i*-1} 1' file
1 -2 -3 4 -5 6
-7 8 -9 -10 -12 0

Using the <var_or_field><op>=<value> construct:

$ awk '{for (i=1;i<=NF;i  ) $i*=-1} 1' file
1 -2 -3 4 -5 6
-7 8 -9 -10 -12 0

CodePudding user response：

Using perl and its autosplit mode:

perl -lane 'print join(" ", map { $_ * -1 } @F)' file

CodePudding user response：

To multiply every number in the file with -1, you can use the following 'awk'command:

   `awk '{ for (i=1; i<=NF; i  ) $i=$i*-1; print }' file`

This command reads each line of the file, and for each field (number) in the line, it multiplies it by -1. It then prints the modified line.

The output will be as follows:

    1 -2 -3 4 -5 6
    -7 8 -9 -10 -12 0

Alternatively, you can use the following 'sed' command:

   sed 's/-\([0-9]*\)/\1/g; s/\([0-9]*\)/-\1/g' file

This command replaces all negative numbers with their positive equivalent, and all positive numbers with their negative equivalent. The output will be the same as above.

CodePudding user response：

For completeness an approach with ruby.

-l Line-ending processing
-a Auto-splitting, provides $F (field, set with -F)
-p Auto-prints $_ (line)
-e Execute code

ruby -lape '$_ = $F.map {|x| x.to_i * -1}.join " "' file
1 -2 -3 4 -5 6
-7 8 -9 -10 -12 0

CodePudding user response：

Just switching the signs ought to do.

$: cat file
1 -2 -3 4 -5 6
-7 8 -9 -10 -12 0

$: sed 's/^ */ /; s/  */  /g; s/  -/ /g; s/  / -/g; s/-0/0/g; s/^ *//;' file
-1 2 3 -4 5 -6
7 -8 9 10 12 0

If you don't care about leading spaces or signs on your zeros, you can drop some of that. The logic is flexible, too...

$: sed 's/ *-/ /g; s/ / -/g; s/ / /g;' x
1 2 3 -4 5 -6
 7 -8 9 10 12 -0