Add the elements of 2 rows based on pattern condition - linux

Question

I want to add 2 rows based on a pattern
I have this table
1 - 513 1478 966 1
2 - 1594 2130 537 1
3 + 2171 2539 369 1
4 - 2587 3159 573 1
What Iam looking for is to add an $7 column with the first element starts with 0 and if the $2 is "-" then substract -1 from $7 else add +1 in the $7
like this:
1 - 513 1478 966 1 -1
2 - 1594 2130 537 1 -2
3 + 2171 2539 369 1 -1
4 - 2587 3159 573 1 -2 `
I wrote this
awk '$7==0,i=1;{for i in $1 do {if($2="-"){$7=$7+1}else{$7=$7-1} done print}'
The issue with my code is that if I remove the for condition turns the entire $2 in - and the entire $7 is -1

Answer 1

Your code is not working at all. It complaints about a couple of syntax errors. In any case, I think you are overthinking the problem. If I didn't understood you wrong, the solution is simpler:
awk 'BEGIN {v=0} {if ($2=="-") {v=v-1} else {v=v+1}; $7=v; print}'
Use a var v to keep the last value and add or substract one depending on $2 content. Once v is updated, assign it to $7 and print the entire record. In the next line you already have the last valu of the seventh column in v.

Answer 2

using #RavinderSingh13's trick
$ awk '{print $0 "\t" (c+=$2"1")}' file
1 - 513 1478 966 1 -1
2 - 1594 2130 537 1 -2
3 + 2171 2539 369 1 -1
4 - 2587 3159 573 1 -2

Answer 3

This should be as simple as the following.
awk 'BEGIN{OFS="\t\t"} {$2=$2"1";$(NF+1)=$2*$NF+prev;prev=$NF} 1' Input_file
Brief explanation:
Adding 1 to $2 2nd field value of every line.
Multiplying value of $2 with last field(which means multiplying 1 with +ve or -ve to last field) and saving its value to newly created last field.
Now adding previous line's last field value to it here as per OP's question.
Saving current last field(new created one by using $(NF+1)) to prev variable so that it could be used to add in next line's calculations.
Detailed explanation:
awk ' ##Starting awk program from here.
BEGIN{ ##Starting BEGIN section of this awk program from here.
OFS="\t\t" ##Setting value of 2 times TAB for each line here.
} ##Close BEGIN section of this code here.
{
$2=$2"1" ##Concatenating 1 to value of $2 here.
$(NF+1)=$2*$NF+prev ##Creating new last field whose value is $2*$NF and adding prev variable to it.
prev=$NF ##Setting current last field value to variable prev here.
}
1 ##Printing edited/non-edited lines here.
' Input_file ##mentioning Input_file name here.
Output will be as follows for provided samples.
1 -1 513 1478 966 1 -1
2 -1 1594 2130 537 1 -2
3 [phone]
4 -1 2587 3159 573 1 -2