CODEWITHSUNDEEP
bashunixsedawk
nkalis
nkalis

Reputation: 13

change the 2nd column from positive to negative and vice versa

How can i change the 2nd column from positive to negative and vice versa

aa.txt

31OCT2013:00:00:00,220.10,"O","090500 13549951"
31OCT2013:00:00:00,-0.32,"I","090500 13549964"

Answer should be

aa.txt

31OCT2013:00:00:00,-220.10,"O","090500 13549951"
31OCT2013:00:00:00,+0.32,"I","090500 13549964"

If i use awk

'BEGIN{FS=OFS=","} {$2=-$2}1' aa.txt

the result is 

1OCT2013:00:00:00,-220.1,"O","090500 13549951"
31OCT2013:00:00:00,+0.32,"I","090500 13549964"

In the first result, sign is changing but 0 is missing, instead of -220.10, it is showing as -220.1.

Upvotes: 1

Views: 1154

Answers (3)

NeronLeVelu
NeronLeVelu

Reputation: 10039

sed 's/^\([^,]*,\)-/\1/
t
s/^[^,]*,/&-/' YourFile

Based on - existance

Upvotes: 1

bazzargh
bazzargh

Reputation: 1842

Use sprintf to format the output.

awk 'BEGIN{FS=OFS=","} {$2=sprintf("%+.2f",-$2)}1' aa.txt

Upvotes: 0

fedorqui
fedorqui

Reputation: 289585

Considering you want to change the second column based on comma, this can be a way:

$ awk 'BEGIN{FS=OFS=","} {$2=-$2}1' aa.txt
31OCT2013:00:00:00,-220.1,"O","090500 13549951"
31OCT2013:00:00:00,0.32,"I","090500 13549964"

See 

31OCT2013:00:00:00,-220.1,"O","090500 13549951"
                   ^
31OCT2013:00:00:00,0.32,"I","090500 13549964"
                   ^

Update

With the previous version we were losing trailing zeros, as per a arithmetic behaviour. To handle it properly, we can do:

awk 'BEGIN{FS=OFS=","} {if ($2>0) $2="-"$2; else sub("-", "", $2)}1' file

In case the value is positive, it adds a dash in front of the string. Otherwise, it just deletes the dash.

Given a sample file

$ cat a
31OCT2013:00:00:00,220.10,"O","090500 13549951"
31OCT2013:00:00:00,-0.32,"I","090500 13549964"
31OCT2013:00:00:00,0.300,"I","090500 13549964"
31OCT2013:00:00:00,-0.300,"I","090500 13549964"
31OCT2013:00:00:00,0,"I","090500 13549964"

It returns

$ awk 'BEGIN{FS=OFS=","} {if ($2>0) $2="-"$2; else sub("-", "", $2)}1' a
31OCT2013:00:00:00,-220.10,"O","090500 13549951"
31OCT2013:00:00:00,0.32,"I","090500 13549964"
31OCT2013:00:00:00,-0.300,"I","090500 13549964"
31OCT2013:00:00:00,0.300,"I","090500 13549964"
31OCT2013:00:00:00,0,"I","090500 13549964

Upvotes: 0

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