subtracting the minimum value in a file with shell script

Question

I need some help with shell script.

I have the following text file (open_calculator[1]):

value:0,0236679
value:0,0272904
value:0,0282416
value:0,0295671
value:0,0318641
value:0,032451
value:0,0333313
value:0,0360229
value:0,0364378

And I need to get the minimum value of this file and subtract it of the other values of the same text file. So my output should be:

value:0,0000000
value:0,0036225
value:0,0045737
.
.
.
value:0,0127699

In order to achieve this, I wrote this script:

file="open_calculator[1]"

min= cut -f2 -d ":" $file | sort -n | head -1
number=$(grep -o '[0-9],[0-9]*' $file)
resul=$((10#$number - 10#$min))

sed -i 's/value:$number/valor:$resul/' $file

but when I run this code, I get this message error:

line 6:10#0,0236679: value too great for base (error token is "0236679")

Someone could help me with this script? Sorry for my bad English, it's my first time writing here.

Thanks in advance!

Do these values denote floating point/decimal numbers ?

Rahul Verma
– Rahul Verma

2017-08-31 20:15:51 +00:00
Commented Aug 31, 2017 at 20:15 — Rahul Verma
– Rahul Verma, Commented Aug 31, 2017 at 20:15
Yes, these values are decimal numbers.

Nands
– Nands

2017-08-31 21:39:59 +00:00
Commented Aug 31, 2017 at 21:39 — Nands
– Nands, Commented Aug 31, 2017 at 21:39

Rahul Verma · Accepted Answer · 2017-08-31 21:14:07Z

2

You can modify your code as following:

tr ',' '.' <open_calculator[1] > file  #Converting each , to . to make these numbers decimal

min=`cut -f2 -d ":" file | sort -n | head -1` 

awk -F":" -v m=$min '{print $1":"($2-m) } ' file | tr "." ","

Output:

value:0
value:0,0036225
value:0,0045737
value:0,0058992
value:0,0081962
value:0,0087831
value:0,0096634
value:0,012355
value:0,0127699

Solution 2 : One liner using awk and tr only

tr "," "." <open_calculator[1] | awk -F":" 'NR==1{a[NR]=min=$2} {a[NR]=$2; a[NR]<min?min=a[NR]:min; } END{for(i=1;i<NR;i++){print "value:"a[i]-min}}' | tr "." ","

Here we are finding min in awk itself and subtracting from second column. The result from awk is piped to tr to translate "." to "," to match your desired output.

edited Aug 31, 2017 at 21:14

answered Aug 31, 2017 at 20:44

Rahul Verma

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4 Comments

Benjamin W. Over a year ago

The desired output is colon separated and uses a comma as the decimal point, though.

Nands Over a year ago

Thank you, batMan. The second solution works fine, but how can I save the output in the file?

Nands Over a year ago

I did it. I just have to use: >> "open_calculator[1]"

Rahul Verma Over a year ago

okay, great. But also mention such requirements in your original question too from next time.

choroba · Accepted Answer · 2017-08-31 20:19:05Z

0

bash doesn't handle floating point arithmetics.

Perl to the rescue:

perl -e 'while (<>) {
             s/,/./;
             ($n) = /([0-9.]+)/;
             $min = $n unless defined $min && $min < $n;
         }
         open ARGV, $ARGV;
         while (<>) {
             s/,/./;
             s/([0-9.]+)/$1 - $min/e;
             s/\./,/;
             print;
         }' -- filename

The first loop finds the minimum, then open reopens the file again and the second loop subtracts the minimum. The substitutions are needed as Perl uses decimal dot, not comma.

answered Aug 31, 2017 at 20:19

choroba

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1 Comment

Nands Over a year ago

Thank you, I didn't know perl, but now I will starting study.

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